[Incidence of Smoking in Women of Childbearing Age][Pregnancy and Smoking][Smoking and Fetal Development]
[Smoking and Childhood Development]

 There is one-hazard associated with smoking which concerns one particularly, and should concern all members of the Interagency Council:  the effects of cigarette smoking in pregnancy.  The 1964 Surgeon General's Report noted that smoking during pregnancy could result in babies of lower than average birth-weight.  At that time there was no evidence that this necessarily affected the biological fitness of the infant.  In our 1967 Health Consequences of Smoking, we advised that in light of this prematurity factor it was "prudent" for pregnant women not to smoke.  In 1969, it was suggested that there was a relationship between smoking during pregnancy and spontaneous abortion, stillbirth, and neonatal death.  now there is a substantial body of evidence which clearly supports the earlier view that maternal smoking during pregnancy harms the unborn child by exerting a retarding influence on fetal growth.  In addition to the already established data on low birth weight in the pregnancies of smoking mother, there is new data on fetal wastage and neonatal death.  One study showed that these women have 20% more unsuccessful pregnancies than they would have if they had not smoked.   The British Perinatal Mortality Survey, the largest prospective study to deal with this question, demonstrated that smoking mothers have significantly more stillbirths and neonatal deaths than non-smoking mothers.

 Fetal wastage is a terrible tragedy, as is the loss of an infant, and let me suggest that certain purveyors of cigarettes stop making awkward remarks about how some young mothers in childbirth might welcome smaller babies.  The mother who smokes if subjecting the unborn child to the adverse effects of tobacco and as a result we are losing babies and possibly handicapping babies.

 The influence of smoking upon pregnancy brings up the whole problem of women and smoking.  One third of all women in the childbearing years are smokers and their numbers are building up as more and more teen-age girls get started on the smoking habit.  In the past seven years, there has been an appreciable drop in smoking among men but regrettably there has been no comparable drop among women....

 From the very beginning the cigarette industry has done everything it could to bring women into the smoking population.  In the early days of advertising, a nonsmoking lady would be shown appealing to her gentlemen companion, "Blow the smoke my way," or saying, "Reach for a Lucky instead of a sweet."  The latter slogan caused considerable furor in the candy industry, but lured many weight-conscious women to take up smoking.  In the past half century, the advertising has become more blatant; women have been enticed by endorsements from ladies of fashion and even opera stars; they have been led to the bait by young, modish, sophisticated models who live and play in elegant settings, accompanied by male companions who are handsome and virile.  To all of this has been added cigarettes just for women, and what could be a more effective way to advertise them than to suggest that the fair sex has come a long, long way since the days when they could smoke only behind closed doors?  The makers of one brand which has just come on the market have promised a veritable flood of print advertising in women's magazines, entertainment programs, newspapers and Sunday supplements, and on billboards.
One of the most important reasons for the low cessation rate among women is the fact that they have yet to experience the toll of death and disease from smoking which men have had.  Partly this is because women, until now, have smoked somewhat differently than men.  As a rule they smoke fewer cigarettes per day, inhale less frequently and less deeply, use lower tar and nicotine cigarettes, and consume smaller portions of each.  Primarily, however, the difference may be explained by the shorter period in which women have smoked.  We know, for instance, that women did not start to smoke in any great numbers before World War 1; thus few in their 70s and 80s have had the same exposure to this health hazard as meen of the same ages.  With each succeeding decade more women did take up smoking, and they started at earlier ages; yet there have always been fewer women smokers, proportionately, than men.  This holds true today despite the changes in smoking habits I have already mentioned.

Since there are fewer women smokers to be affected, the relative death rates from smoking-associated diseases are going to be smaller than those of men.  Furthermore, their overall death rate from almost all other diseases is generally lower than that of men.  A man will see his friends, co-workers, and relatives dying at relatively young ages from heart diseases, lung cancer, and other smoking-related diseases.  A woman may be less conscious of such deaths among her women friends and relatives and consequently feel herself somehow safe from the hazards of smoking.  But this may change.  I want to emphasize that while men's death and disability days are higher than women's, the woman smoker has a higher death rate than the nonsmoking woman.

Currently, girls are rushing to emulate the cigarette smoking practices of boys.  What will happen to these young smokers?  Some will stop once the glamour wears off and their crowds disperse after high school days are over.  A very large number will undoubtedly continue to smoke, for a habit started that early in life is one that is hard to break....

The plethora of ads promised by the tobacco industry is of concern on two counts.  First, it may encourage young people to take up smoking; but more important, it may tend to shake the resolve of those who sincerely want to quit.  An overwhelming dose of ads in women's magazines could have such an effect, for women basically find it harder to give up smoking than men and even those who quit are more likely to return to smoking than men.  Data for 1970, for instance, shows that above 25% of all men smokers managed to quit, while only 15% of women smokers were able to give up the habit.

We do not know why women have not made a better showing.  Perhaps it is an affirmation of the desire to break away from old social restrictions.  Certainly, advertising has played a part.  It may be that the housewife's basic environment is more conducive to continue smoking, particularly if she is alone part of the day.  In the business world, smoking undoubtedly helps create a sense of equality with men.  Some women keep up the smoking habit because of the fear of weight gain that may accompany cessation.

Today, even though cigarette commercials are now off the air, a new broadside attack through the print media is bound to have considerable impact.  The onslaught has already started.  My staff counted a total of 36 cigarette advertisements currently carried in eight of the leading magazines aimed exclusively at women.  One of them has eight such ads in the current issue.  These journals are not just the kind that stress hair styling, grooming, and the secrets of being popular.  Those surveyed included homemaking magazines which carry articles on child care and household hints - journals that have wide popular appeal to women in all walks of life....
The health professions must become more active in the smoking and health field.  Obstetricians and gynecologists should have a particular concern about smoking's effect on their patients.  One group of professionals has a particular stake in this effort - not only because they are women, but because they have an opportunity to exert a considerable influence on other women.  I refer to our nurses who play an important role in so many areas of health care - in hospitals, clinics, physicians' offices, industrial health units, school health programs.  The American Nurses' Association two years ago passed a resolution calling on its members to be informed about the health hazards of cigarette smoking and encouraging them to involve themselves in positive health education programs to prevent nonsmokers, particularly youngsters, from starting to smoke.  I regret to say that there are still more smokers proportionately among nurses than among women generally.  Of course, I do not mean to suggest that our efforts should be limited to women or that menand boys should be neglected in future educational campaigns.  Our obligation is to all segments of the population, our challenge is to turn back the new rising tide of cigarette consumption.
Finally, evidence is accumulating that the nonsmoker may have untoward effects from the pollution his smoking neighbor forces upon him.  Nonsmokers have as much right to clean air and wholesome air as smokers have to their so-called right to smoke, which I would redefine as a "right to pollute."  It is high time to ban smoking from all confined public places such as restaurants, theaters, airplanes, trains, and buses.  It is time that we interpret the Bill of Rights for the Nonsmoker as well as the smoker.

Incidence of Smoking among Adults of Childbearing Age

 Women did not start to smoke in any appreciable number until the 1920's, but that has certainly changed.  As a current cigarette advertisement proclaims, "You've come a long way, baby!"  The habit became sufficiently popular for an obstetrician to note in 1936 (2) that "the excessive smoking and inhaling of cigarettes...during the last two decades has clutched the young women of this country in a manner resembling the invasion of an epidemic working in virgin soil."  The same physician said a year earlier (3) that "a quarter of a century ago it was extremely rare to encounter a pregnant woman who smoked even moderabely...(but) the incidence of smoking...in the last decade (of the 1920's)...has greatly increased..."

 The United States Department of Health has estimated that the consumption of cigarettes among women during the 1920's was approximately 135 packs annually compared to 244 packs for men annually.  Approximately 5 percent of the adult women smoked, compared to about 50 percent of the adult men (4).  The sad fact for women is that during the next half-century, the percentage of those smoking has markedly increased to 28.2 percent, while the corresponding percentage among men has decreased to 36.9 percent (5).  The number of cigarettes smoked per day is also increasing for women.  In 1955, female smokers of childbearing age smoked an average of 6.4 cigarettes, but in 1966, the average consumption had increased to 9.5 cigarettes per day (6).

 Population studies of pregnant women throughout the world show an alarming consistency with approximately 40 percent of all women smoke during their pregnancy.  With this degree of fetal exposure, it becomes rather imperative to ascertain the effects of smoking upon pregnancy.
Pregnancy and Smoking

 Dr. Steinfeld also expressed concern about the effect of cigarette smoking upon the health of the unborn (1).  The effect of tobacco smoking upon fetal development has received a great share of attention through the years.  Generally, there had been almost uniform concern that smoking would be harmful to the developing fetus, although until recently there was a great paucity of information.   According to recent research in this area, however, these early concerns were not unwarranted and were largely vindicated.

  Cigarette smoking by the pregnant mother is injurious to the health of the unborn life inside her womb.  Concern about the effect of smoking on fetal health dates back many centuries, at least to a 1606 treatise by an English physician Dr. D.E.,  In this work, the physician expressed concern about how smoking might affect the father's health (7):

 ...I see not therefore how Tobacco can be acquitted from procuring the overthrow of the perfect state both of body and minde:  and that not onlie in Tobacconists themselves, but in their posterity also; for the temperament and constitution of the father is ordinarily transfused into the children, and the affections of the minde also, depending upon the other...Therefore where the humours of the body have contracted a sharpe heat and drinesse by smoking of tobacco, there the father getteth a child like to himselfe, wanting the kinde moisture that should protract his life unto olde age...

 These sentiments were further reflected by Francis Bacon's Sylva Sylvarum (8) which in 1626 reflected upon the effect of tobacco and alcohol upon the infant, that to "drink wine, or stronge drinke, immoderately; or fast much; or be given to much musing...endangereth the childe to become lunaticke, or of imperfect memory:  And I make the same judgment of tobacco, often taken by the mother."

 Later in that century, a noted London physician, Dr. E. Maynwaring (9), asserted "...this I may assert, that it causeth an unfirm generation, by debilitating the parents...and makes a diseased issue."

 Concerns about the relationship between tobacco smoking and infant disease did not receive much critical investigation until a report by Sontag and Wallace in 1935 (11) which noted a rise in fetal heart rate coinciding with smoking by the mother.  Animal studies during the 1930's and 1940's demonstrated that cigarette smoke or nicotine could increase the rate of spontaneous abortions and reduce birth weight (11-13).  However, these investigations were not considered relevant to humans by the scientific community of that day and were largely ignored.

 The situation began to change in the late 1950's with the publication of two monumental articles.  These investigations by Simpson in 1957 (14)  and Lowe in 1959 (15) clearly demonstrated an adverse effect of cigarette smoking on fetal development.  These effects were shown to be dependent upon the number of cigarettes smoked and not to other non-specific factors such as maternal age, number of previous births, etc.  Since then, there has been considerable investigation into the effects between cigarette smoking and fetal development, which has resulted in a greater understanding of the serious ways in which smoking affects fetal and newborn development.

Relationship Between Smoking and Fetal Development
[Spontaneous Abortions][Infant Birth Weight][Infant Mortality][Infant Malformations][Apgar Scores]

Spontaneous Abortions

 The possibility that smoking may produce an increased incidence of abortions has been considered as early as the 17th century, but was first critically examined by Ballantyne in 1902 (16).  In that report, he summarized the information available, and felt that smoking during pregnancy might be responsible for "cutting short antenatal life."

 Mgalobeli (17) raised the issue again in 1931 in when he reported that women who worked in tobacco factories had a higher incidence of spontaneous abortions than other women.  However, his conclusions were rather poorly substantiated.

 However, recent large scale epidemiological investigations leave little doubt that the association is valid; smoking can indeed increase the rate of spontaneous abortions.

 Zabriskie (18) showed in a retrospective study of 5000 pregnancies, and O'Lane indicated in a study of 2000 pregnancies that the rates of spontaneous abortion among smokers were 12.6 percent in both, while the spontaneous abortion rate among the control non-smoking population was 8.8 and 8.9 percent respectively.
 In New York State, Kline et al. (19) showed a 1.8 times greater incidence of spontaneous abortions among smokers compared to snon-smokers.  In this particular study, women were matched for age, number of births, marital status, ethnic group, and social class.

 In Dublin, Ireland, Murphy and Mulcahy (20) reported on 12,013 pregnancies and also established a significant relationship between spontaneous abortions and smoking status.

 In Sweden, Palmgren and Wallander (21) investigated 4312 pregnancies and reported a spontaneous abortion rate of 14.5 percent for smokers compared to a rate of 7.8 percent for non-smokers:  approximately twice the risk.

 A risk of between 1.2 and 1.7 was calculated for a group of 12,194 pregnancies studied by Himmelberter et al. (22) even after other risk factors were seriously considered.

 Schramm (23) studied the 68,115 births in Missouri in 1978 and demonstrated a higher incidence of spontaneous abortions among smokers than non-smokers, although the rate was even higher for non-Whites than Whites.  Among the Whites, the rate was 8.4 vs 6.3 per 1000 live birth for smokers and non-smokers, while the rate for non-Whites, the rates were 18.0 and 10.2 for smokers and non-smokers respectively.

 The precise reason why smokers tend to have more spontaneous abortions than non-smokers is currently unclear.  The theories advanced to explain this difference include abnormal placental development during pregnancy, abnormal development of the embryo and fetus, or by adversely affecting the delicate hormonal balance present during pregnancy and necessary for sustaining the viability of both the fetus and placenta.

Birth Weight

 Birth weight is a very important parameter as it is a good parameter for post-natal development, especially when the birth weight is less than 2500 grams.
 It has become well established with multiple good studies (that there is a reduction of birth weight of children born to smoking mothers from 40 to 430 grams, or an average of approximately 200 grams (7 ounces) compared to other children.  Additionally, these offspring tend to be about 1.4 cm (about 1/2 inch) shorter than children of non-smoking women.  In some studies, the rather important parameter of head circumference has also found to be reduced.

 These reduction of birth weight, shortness, and decreased head circumference appear to be due to intrauterine growth retardation and not to prematurity.  In other words, these children were not born too early and therefore too small, but rather grew too slowly over a normal gestation period.

 The lower birth weight produces an infant mortality rate many times higher than that or other infants.  There is a direct correlation between the number of cigarettes smoked and birth weight; the more a woman smokes, the lower her baby's birth weight.  There also appears to be a critical difference between the small babies born to smoking smothers and those born to malnourished mothers.  Small babies born to malnourished mothers are small, but tend to catch up to their peers.  However, this does not appear to be true with babies born to smoking mothers since these babies remain small for extended periods of time.

 Importantly, if the smoker stops smoking, then these harmful effects upon the developing infant are not seen.  Thus, a smoker who stops smoking during pregnancy will tend to have normal babies with normal birth weight.  Thus, it is the smoking itself and not something abnormal with the mother that is the cause of the fetal abnormalities.  While it is not known whether there is a definite time during pregnancy when cigarette smoking has the greatest detriment, it is thought likely that smoking during the last trimester will  produce the greatest adverse impact on fetal growth (as does alcohol and marihuana).

Perinatal Mortality

 Since the birth weight of infants born to smokers is lower than those born to non-smokers, it would be logical to assume that the mortality rate of these low birth weight infants is higher.  The evidence suggests that this may indeed be the case, as overall perinatal mortality and stillbirth rate are higher in smokers than in nonsmokers (34-36,41-43), but the relationship between maternal smoking and infant mortality is somewhat less clear-cut than between maternal smoking and low birth weight.  In some cases, this is due to study design deficiencies which introduced biases of one type or another (7).  Additionally, recent evidence also indicates that maternal smoking may increase the risk of neonatal death mostly for women who are already high risk, such as low socioeconomic groups, race, and maternal age (44).  Additionally, many factors may affect birth weight such as infant gender (male babies are larger than female babies but they both have the neonatal mortality rate) (7), so that there is not a simple relationship between infant weight and mortality.   Thus, while it is certainly true that smoking causes low birth weight babies who might logically be considered to have an increased risk of bad outcome, the relationship between smoking and infant death is less clear and might not be entirely or even partially due to low birth weight.  More epidemiological work needs to be done in this area to better define the specific risk factors for infant mortality in the mothers who smoke.

Fetal Malformations

 Spontaneous abortions may occur either early or late in pregnancy.  Those occurring early in pregnancy are often associated with chromosomal aberrations or malformation of the developing fetus (7).  Alternatively, spontaneous abortions occuring late in pregnancy are often associated with complications of pregnancy rather than malformations.  Thus, if cigarette smoking were associated more with birth complications of late pregnancy than with chromosomal malformations of early pregnancy, then there would be an explanation for the lack of increased chromosomal malformations seen among smoking women as reported by Alberman et al (45).

 Most investigators have not reported an increase in congenital malformations among the stillborns of women who smoke.  Andrews and McGarry (46) reported the number of stillborns due to congenital malformations was 0.27 per 100 for smokers but was 0.32 per 100 for non-smokers in their study of 18,631 pregnancies.  Meyer and Tonascia (41) also reported a lack of significant differences between smokers and non-smokers for congenital malformation.

 However, other studies are not quite so clear.  Naeye (47) reported that for all gestational ages, there was an increased rate of malformations that progressively increased with the number of cigarettes smoked over 10 per day.  Additionally, he reported that anencephaly (born without full development of brain) was especially more common among women who smoked greater than 10 cigarettes per day.  Also, Fedrick et al. (48) reported an increase in the incidence of congenital heart disease of 0.73 per 100 births among women who smoked compared to 0.47 per 100 among women who did not smoke.  The usual types of congenital heart disease found among smokers were patent ductus arteriosis and tetralogy of Fallot - both of which are very serious types of heart disease although not necessarily fatal.  A slightly higher incidence of congenital heart disease was also reported by Andrews and McGary (46) and Himmelberger et al (22).

 Finally, other investigators have found an increased incidence in the number of congenital facial diseases such as cleft palate or cleft lip among the children of smokers compared to those of nonsmokers.  In an investigations by Andrews and McGarry (46), there was a 0.26 percent incidence of these abnormalities among smokers, while there was only a 0.11 percent incidence among non-smokers. Kelsey (49) also reported an increased incidence of these abnormalities among women who smoked greater than one pack per day.

 In conclusion, there does appear to be a greater incidence in the incidence of spontaneous abortions among women who smoke, as reported in the first section of this discussion.  While there is not an increased incidence of chromosomal abnormalities (probably indicating normal initial fetal development), there may be an increased incidence of congenital malformations, possibly indicating difficulty with the latter stages of pregnancy.  The congenital malformations that have been linked to smoking include congenital heart disease, cleft lip and cleft palate, and the very serious and fatal disease anencephaly.

Apgar Scores

 Apgar scores are used by the pediatrician to determine the viability of a newborn infant, and to prognosticate which newborn is most likely to run into significant difficulty in the first few days of life.  This evaluation is often done within the first few minutes of birth, and takes into consideration the infant heart rate, respiratory rate, muscle tone, response to a tube in the nostril (no response, grimace, cough or sneeze, etc.), and infant color (pink or blue).  There is a fairly good corrolation between the Apgar score and infant mortality within the first month of life, especially for infants who have a low birth rate (as is more frequently seen in infants of mothers who smoke).

 The National Collaborative Perinatal Project Study (50) analyzed 43,492 infants and observed a depression of the Apgar scores that was corrolated with the number of cigarettes smoked by the mother.  Smoking of more than 2 packs per day was associated with a fourfold increase in the incidence of Apgar score depression compared to those infant born to non-smokers.  A similar effect was also noted by Bosley et al. (51) in their investigation.  However, when birth weight was taken into account, the picture becomes less clear.  The reduction in Apgar scores for infants born to mothers who smoke was no greater than might be expected due to impairment associated with low birth weight alone.

The Relationship Between Maternal Smoking and Long Term Effects Upon the Child
[Child Growth][Sudden Infant Death Syndrome][Respiratory Disorders][Childhood Cancers][Behavioral Effects]

Child Growth

 The differences in growth rates between children born to smoking mothers or nonsmoking mothers are seen very early.  Russell et al. (52) reported in 1968 that at 1 year of age there was a 0.3 kg (about 1/2 pound) decreased weight among children born to smoking women compared to non-smoking women.  A similar difference was also found by Handy and Mellits (53) in 1972.

 This deleterious effect that smoking has on childhood growth continues through childhood life.  Wingerd and Shoen (54) found that children born to smokers were 0.9 cm (about 1/3 inch) shorter than children of nonsmokers, and at age 7, Hardy and Mellits demonstrated a 1.0 cm difference (which was, however, not statistically different).  By age 7, the British Perinatal Mortality Study (55) demonstrated a 1.4 cm height difference between children of smokers compared to non-smokers, and at age 11, this difference had increased to 1.6 cm.  An increased difference between the two groups persisted when the series was adjusted for other variables such as social class, family size, maternal height, etc.  While these differences are admittedly quite small, they are found consistently among series looking at this problem.  Thus, children born to women who smoke tend to remain small for their age for many years after birth.

Sudden Infant Death Syndrome (SIDS)

 Sudden infant death syndrome (also known as crib death, cot death, sudden unexpected death in infancy) is the most common cause of death in infants under one year of age in America.  It occurs in about 2 to 3 infants out of 1000 live births (56), and refers to the "sudden, unexpected death of an infant in the absence of any history or observable cause."  It is often very damaging to familial relationships, and has been the cause of many divorces.  It is particularly tragic because the death is so sudden to otherwise very healthy infants.  There is often a large sense of guilt, depression, and feelings of inadequacy.  Additionally, SIDS can be particularly difficult for the family to endure because there is no known cause, little that can be done, and a propensity to run in families.

 Recent investigations have added considerably to our fund of knowledge about this very disastrous entity.  The epidemiological studies by Naeye et al. (57) and Lawak et al. (58) have reported that maternal smoking is associated with an increased incidence of SIDS in their children.

 In the Naeye study, 125 children with SIDS were compared with 375 other healthy infants and matched for possible contributing factors including place of birth, date of delivery, gestations age, sex, race, and socioeconomic status.  When the data was examined, women who smoked regularly during their pregnancy were more likely to have an infant with SIDS than were non-smoking women, and this likelihood increased markedly when the women smoked greater than six cigarettes per day.

 Lawak et al. (58) performed a similar study by comparing 44 infants with SIDS to 18,716 infants who were otherwise healthy.  Again, maternal smoking was determined to be significantly related to the chance of a child having this syndrome.  Indeed, 70.6 percent of infants with SIDS had mothers who smoked.  On the other hand, paternal smoking or alcohol consumption by either parent was not related to SIDS.  Lawak calculated that maternal smoking approximately doubles the risk of SIDS from 2.3 to 4.6 cases per 1000 births.

 There have been many attempts to determine the mechanism whereby maternal smoking induces SIDS in newborns.  Generally, these investigations have not been too rewarding, partially because SIDS itself is such a poorly understood entity with no clear cause.  Naeye, however, noted that SIDS victims exhibit symptoms suggestive of damage to the brain stem which controls, among other things, breathing.  He noted that these infants often have difficulty with elevation of arterial concentrations of carbon dioxide (pulmonary hypoventilation) and lowered arterial concentrations of oxygen (hypoxemia).  Other investigators have suggested that these symptoms may be due to damage to certain parts of the developing infant due to constant exposure to the low oxygen environment which may be present in the womb of the smoking mother.

 Getts and Hill (59) further extended this hypothesis by examining the incidence of SIDS at high altitude, where the air is thinner, there is less oxygen available, and where the developing intant might be expected to develop SIDS according to the above hypothesis.  Indeed, what they found was an increase in the incidence of SIDS compared to the rate seen in mothers living at lower altitudes.  This piece of confirmatory evidence by Getts and Hill provides another very cogent reason why a pregnant woman should not smoke.

Respiratory Disorders in Children

 An increased incidence of pneumonia and bronchitis among children of smoking women compared to non-smoking women has been established in several studies.  Additionally, both the Harlap and Davies study (60) and the Colley et al. study (61) demonstrated that the increased incidence of pneumonia and bronchitis among children of smoking mothers increased as the number of cigarettes smoked by their mothers increased.  This increased incidence of respiratory diseases may be due either to passive smoking by the infant, or to prenatal exposure of the fetus to effects of maternal smoking which lower the resistance of these children to infections after birth.

Susceptibility to Cancer

 There is little good evidence that the children of mothers who smoke have a greater incidence of cancer than children of women who do not smoke.  However, Stewart et al. (62) reported an increase in cancer patients of mothers who smoked, but this was not corroborated by other investigations.  However, Neutel and Buck (63) found that among 89,302 children, there was a 1.3 times greater tisk of cancer up to ten years of age among those children whose mothers smoked.  It might be possible that had the age limit been lengthened to greater than 10 years, the incidence might have been even greater since some cancers require many years to develop.

 The contention that maternal smoking may increase the risk of cancer development in the offspring has received its greatest support from animal studies.  Bulay and Wattenburg (64) reported that the offspring of mice injected with benzo(a)pyrene (a very potent carcinogen found in the tar component of cigarettes) developed a greater incidence of tumors of the lung, liver, breasts, and skin compared to control mice.  Hamsters exposed to cigarette smoked condensate also had offspring with a greater incidence of cancers than other hamsters.  Although the dosages used in these investigations far exceeded comparable amounts of exposure in humans exposed to cigarette smoke, the principal is the same.  Since these animals often not develop their tumors until relatively late in life, future studies in humans should probably examine this issue in a more elderly population.

Behavioral Effects

 At the University of Washington, a large prospective "Pregnancy and Health Study" was conducted to study the behavior of infants at the second day of life.  The study examined primarily the effect of alcohol exposure on the newborn, but also investigated maternal smoking exposure during pregnancy.  In the first study, Landesman-Dwyer et al. (65) noted that infants born to women who both smoked heavily (greater than 16 grams of nicotine per day) and drank heavily (2 or more drinks during pregnancy) had subtle behavioral abnormalities.  They tended to be less visually alert and appeared dazed, yawned and sneezed more than other infants.  However, these effects were not seen in infants from mother who only smoked during pregnancy and did not drink.
 In a second study, Martin et al. (66) noted that infants exposed to both alcohol and cigarette smoking during fetal life performed worse on two conditioning tasks - head turning and sucking than those infants who did not have this exposure.

 In a third study, Martin et al. (67) noted that infants born to mother who smoked during pregnancy (but did not drink) had a weaker suck, took longer to begin sucking, and took longer to complete sucking than did control infants.

 In each of these three studies in the "Pregnancy and Health Stuch," the infants were assessed blindly so that the examiners did not know to which group the infants belonged.  Still, there were significant behavioral differences between those infants exposed either to smoking, or both smoking and drinking through the mother.
 An investigation by Landesman-Dwyer et al. (68) further studied the affect of maternal smoking on later infant and childhood development by evaluating the effects of prenatal tobacco smoke exposure upon behavior at 4 years of age.  These children were more willing to approach stranges and novel situations.  Additionally, they tended to have more "negative" behaviors when upset, but these behaviors were not statistically different.

 Another extensive longitudinal investigation was performed on 17,000 children both in England in 1957 (55).  These children were matched on the basis of multiple parameters including gestational age, social class, ethnic background, etc. and their school performed noted in relation to maternal smoking history.  Interestingly, there was a significant impairment of general ability, reading understanding, and mathematics compared to those children who were born to mothers who did not smoke.  These differences, however, were rather small in comparison to other differences such as number of siblings and social class.  Still, even when these other factors were taken into consideration, there were statistically significant differences between the two groups.

 Another study performed by Dunn et al. (69) investigated 519 children who were given a series of neurological and behavioral studies at 6.5 years of age.  Children who were born to smoking mothers had significantly lower scores on psychomotor skills, language abiltity and IQ than did children born to mothers that did not smoke.   Additionally, there was a greater tendency for these children to be classified as having "minimal cerebral dysfunction" but these differences were not statistically significant.  The authors concluded, "children whose mothers smoked during pregnancy have slightly less satisfactory neurological and intellectual maturation by the age of about 6 1/2 years than their counterparts whose mothers did not smoke."

 Another study by Denson et al. (70) investigated the possible relationship between "hyperkenetic" children and maternal smoking.  They matched 20 hyperkinetic children with 20 nonhyperkenetic but dyslexic children with controls matched for sex, age, and social class.  They report that hyperkinetic children were more likely to mothers who smoked during pregnancy than other children.  A similar result was reported by Nichols in a study based upon 28,000 children in the Collaborative Perinatal Project.

 Thus, the neurologic and psychologic development of children born to mothers who smoke may show subtle abnormalities.  These include reduced sucking ability, greater tendency toward becoming hyperkinetic, reduced psychomotor skills, linguistic ability, IQ scores, and less alertness.

References
Smoking and the Women

1. Steinfeld, J.L.  New York State Journal of Medicine, 1257-6, 1983.
2. Campbell, A.M.  The Effect of Excessive Cigarette smoking on Maternal Health.  Am. J. Obstet. Bynecol. 31, 502, 1936.
3. Campbell, A.M.  Excessive Cigarette smoking in Women and its Effect upon their Reproductive Efficiency.  J. Mich. Med. Soc. 34, 146, 1935.
4. Haenszel, W., Shimkin, M.B., Miller, H.P.  Tobacco Smoking Patterns in the United States, U.S. Public Health Monogr. No. 45, Public Health Serv. Publ. No. 463, U.S. Government Printing Office, Washington, D.C. 1956.
5. U.S. Public Health Service.  the Health Consequences of Smoking for Women.  A Report of the Surgeon General, Office on Smoking and Health, U.S. Department of Health and Human Services, Rockville, MD., 1980.
6. Horn, D., Adult Use of Tobacco, Publ. No. (HSM) 73-8728, National Clearinghouse for Smoking and Health, Public Health Service, Washington, DC  1970.
7. Abel, E.L (ed.)., Marihuana,a Tobacco, Alcohol, and Reproduction, CRC Press, Inc., Boca Raton, FL., 1983.
8. Bacon, F., Sylva Sylvarum, London, 1626, Reprinted in The Works of Francis Bacon, Longmans & Co., London, 1887.
9. Brooks, J.E., Tobacco, Its History Illustrated by the books, Manuscripts and Engravings in the Library of George Arents, Jr., Together with an Introductory Essay, a Glossary, and Bibliographic Notes, Vol. 1, Rosenbach Co., New York, 1937, 1507.
10. Sontag, L.W., Wallace, R.F.  The Effect of Cigarette Smoking during Pregnancy upon the Fetal Heart Rate.  Am. J. Obstet. Gynecol. J., 29, 77, 1935.
11. Essenbert, J.M., Schwind, J.V., Patras, A.B.  The Effects of Nicotine on Cigarette smoke on Pregnant Female Albino Rats and their Offspring.  J. Lab. Clin. Med. 25, 708, 1940.
12. Pechstein, L.A., Reynolds, W.R.  The Effect of tobacco Smoke on the Growth and Learning Behavior on the Albino Rat and its Progeny.  J. Comp. Psychol., 24, 459, 1937.
13. Schoeneck, F.J., Cigarette Smoking in Pregnancy.  N.Y. State J. Med., 41, 1945, 1941.
14. Simpson, W.J.  A Preliminary Report of Cigarette Smoking and the Incidence of Prematurity.  Am. J. Obstet. Gynecol. 73, 808, 1957.
15. Lowe, C.r., Effect of Mothers' Smoking Habits on Birth Weight of their Children.  Br. Med. J. 2, 673, 1959.
16. Ballantyne, J.W.  Manual of Antenatal Pathology and Hygiene.  the Fetus.  William Green & Sons, Edinburgh, 1902.
17. Mgalobeli, M.  Eingluss der Arbeit in der Tabakindustrie auf die Geschlechtssphare der Arbeiterin, Monatschr. Gerburtshilfe Gynakol., 88, 237, 1931.
18. Zabriskie, J.E.  Effect of Cigarette Smoking during Pregnancy.  Obstet. Gynecol., 21, 405, 1963.
19. Kline, J., Stein, Z.A., Susser, M.  Smoking as a Risk Factor for Spontaneous Abortion.  N. Engl. J. Med., 297, 793, 1977.
20. Murphy, J.F., Mulcahy, R.  The Effect of Cigarette Smoking, Maternal Age, and Parity on the Outcome of Pregnancy.  J. Ir. Med. Assoc. 67, 309, 1074.
21. Palmgren, B., Wallander, B.  Cigarettetrokning och abort:  Konbsekutiv Prospektivc Undersokning av 4312 Graviditeter, Lakatidningen, 68, 2611, 1971.
22. Himmelberger, D.U., Brown, B.W., Cohen, E.N.  Cigarette Smoking during Pregnancy and the Occurrence of Spontaneous Abortion and Congenital Abnormality.  Am. J. Epidermiol. 108:470, 1978.
23. Schramm, W.  Smoking and Pregnancy Outcome. Mo. Med. 77, 619, 1980.
24. Comstock, G.W., Shah, F.K., Meyer, M.B.  Low Birth Weight and Neonatal Mortality Rate Related to Maternal Smoking and socioeconomic Status.  Am. J. Obetet. Gunecol. 111, 53, 1971.
25. Cope, L., Lancaster, P., Stevens, L.  Smoking in Pregnancy.  Med. J. Aust, 1, 73, 1973.
26. Davies, D.P., Gray, O.P., Ellwood, P.C., et al.  Cigarette Smoking in Pregnancy:  Associations with Maternal Weight Gain and Fetal Growth.  Lancet, 1, 385, 1976.
27. Hajeri, H.  Smoking during Pregnancy and Maternal Weight Gain.  J. Perinat. Med. 7, 33, 1979.
28. Hardy, J.B., Melits, E.D.  Does Maternal Smoking during Pregnancy have a Long-Term Effect on the Child?  Lancet 2, 1332, 1972.
29. Kullander, S., Kallen, B.  A Prospective Study of Smoking and Pregnancy.  Acta Obstet. Gynecol. Scand.  50, 83, 1971.
30. Miller, G.C., Hassenein, K., Hensliegh, P.A.  Fetal Growth Retardation in Relation to Maternal Smoking and Weight Gain in Pregnancy. Am. J. Obstet. Gynecol. 125, 55, 1976.
31. Mulcahy, R., Murphy, J., Martin, F.  Placental Changes and Maternal Weight in Smoking and Nonsmoking Mothers.  Am. J. Obstet. Gynecol. 106, 703, 1970.
32. Naeye, R.L.  Relationship of Cigarette Smoking to congenital Anomalies and Perinatal Death.  Am. J. Pathol. 90, 289, 1978.
33. Palmgren, B.R., Wahlen, R., Wallander, B.  Toxemia and Cigarette Smoking during Pregnancy:  Prospective Consecutive Investigation of 3927 Pregnancies, Acta Obstet. Gynecol. Scand.  52, 183, 1973.
34. Rantakallio, P.  The Effect of Maternal Smoking on Birth Weight and the Subsequent health of the Child.  Early Hum. Dev. 2, 371, 1978.
35. Rush, D., Kass, E.H.  Maternal Smoking:  A Reassessment of the Association with Perinatal Mortality.  Am. J. Epidemiol., 96, 183, 1972.
36. Schwartz, D., Goujard, J., Kaminski, M. et al.  Smoking and Pregnancy:  Results of a Prospective Study of 6898 Women.  Rev. Eur. Etud. Clin. Biol. 17, 867, 1972.
37. Spira, A., Phillips, F., Spira, N.  Smoking during Pregnancy and Placental Pathology.  Biomedicine 27, 266, 1977.
38. Tsafir, J., Halbrecht, I.  birth Weight in Various Population Groups in Israel.  Soc. Biol. 20, 71, 1973.
39. Yeung, D.L., Pennell, M.D., Leung, M. et al.  Effects of Maternal Cigarette Smoking during Pregnancy on Birth Size, Growth of Infants, and Infant Feeding Practices.  Nutr. Rep. Int. 23, 887, 1981.
40. Yerushalmy, J.  Infants with Low Birth Weight Born Before their Mothers Started to Smoking Cigaettes.  Am. J. Obstet. Gynecol. 112, 277, 1972.
41. Meyer, M.B., Tonascia, J.A.  Maternal Smoking, Pregnancy Complications, and Perinatal Mortality.  Am. J. Obstet. Gynecol., 128, 494, 1977.
42. Meyer, M.B., Jonas, B.S., Tionascia, J.A.  Perinatal Events Associated with Maternal Smoking during Pregnancy.  Am. J. Epidemiol., 103, 464, 1976.
43. Rantakallio, P., Relationship of Maternal Smoking to Morbidity and Mortality of the Child up to the Age of Five.  Acta. Paediatr. Scand. 67, 621, 1978.
44. U.S. Department of Health, Education and Welfare, Smoking and Health, A Report of the Surgeon Genera. Publ. No. (PHS) 79-50066, Public Health Service, Washington, D.C., 1979.
45. Alberman, E., Creasy, M., Elliot, M., et al.  Maternal Factors Associated with Fetal Chromosomal Anomalies in Spontaneous Abortions.  Br. J. Obstet. Gynecol. 83, 621, 1976.
46. Andrews, J., McGarry, J.M.  A Community Study of Smoking in Pregnancy.  J. Obstet. Gynecol. Br. Communw. 79, 1057, 1972.
47. Naeye, R.L.  Relationship of cigarette Smoking to Congenital Anomalies and Perinatal Death.  Am. J. Pathol. 90, 289, 1978.
48. Fedrick, J., Alberman, E.D., Goldstein, H.  Possible Teratogenic Effect of Cigarette Smoking.  Nature (London), 231, 529, 1971.
49. Kelsey, J.L., Dwyer, T., Holfort, T.R., et al.  Maternal Smoking and Congenital Malformations:  An Epidemiologic Study.  J. Epidemiol. Community Health, 32, 102, 1978.
50. Garn, S.M., Johnson, M., Ridella, S.A., et al.  Effect of Maternal Cigarette Smoking on Apgar Scores.  Am. J. Dis. Child., 135, 503, 1981.
51. Bosley, A.R., Newcome, R.G., Dauncey, M.E.  Maternal Smoking and Apgar Score.  Lancet, 1, 337, 1981.
52. Russell, C. C., Taylor, R., and Law, C.E.  Smoking in Pregnancy, Maternal Blood Pressure, Pregnancy Outcome, Baby Weight and Growth and Other Related Factors: A Prospective Study.  Br. J. Prev. Sov. Med. 22, 119, 1968.
53. Hardy, J. B., and Mellits, E. D.  Does Maternal Smoking during Pregnancy have a Long-Term Effect on the Child?  Lancet 2, 1332, 1972.
54. Wingerd, J., and Schoen, E.G.  Factors Influencing Length at Birth and Height at Five Years.  Pediatrics 53, 737, 1974.
55. Butler, N.R., and Goldstein, H.  Smoking in Pregnancy and Subsequent Child Development.  Br. Med. J. 4, 573, 1973.
56. Valdes-Dapena, M. A.  Sudden Infant Death Syndrome:  A Review of the Medical Literature, 1974-1979, Pediatrics, 66, 597, 1980.
57. Naeye, R. L., Ladis, R., and Drage, J. S.  Sudden Infant Death Syndrome, Am. J. Dis. Child. 130, 1207, 1976.
58. Lewak, N., Van den Berg, B. J., and Beckwith, J. B.  sudden Infant Death Syndrome Risk Factors: Prospective data Review, Clin. Pediatr. 18, 404, 1979.
59. Getts, A. G., and Hill,. H. F.  Sudden Infant Death Syndrome:  Incidence at Various Altitudes.  Dev. Med. Child Neurol. 24: 61, 1982.
60. Harlap, S., and Davies, A. M.  Infant Admissions to Hospital and Maternal Smoking.  Lancet 1, 529, 1974.
61. Colley, J. R. T., Holland, W. W., and Corkhill, R. T.  Influence of Passive Smoking and Parental Phlegm on Pneumonia and Bronchitis in Early Childhood.  Lancet, 2, 1379, 1974.
62. Stewart, A., Webb, J., Hewitt, D.  A Survey of Childhood Malignancies.  Br. Med. J.  1, 1495, 1958.
63. Neutel, C. I., and Buck, C.  Effect of Smoking During Pregnancy on the Risk of Cancer in Children.  J. Natl. Cancer Inst. 47, 59, 1971.
64. Bulay, O. M., and Wattenberg, L. W.  Carcinogenic Effects of Subcutaneous Administration of Benzo(a)pyrene during Pregnancy on the Progeny.  Proc. Soc. Exp. Biol. Med. 135, 84, 1970.
65. Landesman-Dwyer, S., Ragozin, A. S., and Little, R. E.  Behavioral Correlates of Prenatal Alcohol Exposure:  A Four-Year Follow-Up Study.  Neurobehav. Toxicol. Teratol., 3, 187, 1981.
66. Martin, J. C., Martin, D. C., Lund, C., and Steissguth, A. P.  Maternal Alcohol Ingestion and Cigarette Smoking and their Effects upon Newborn Conditioning.  Alcoholism: Clin. Exp. Res. 1, 243, 1977.
67. Martin, D. C., Martin, J. C., Streissguth, A. P., and Lund, C. A.  Sucking Frequency and Amplitude in Newborns as a Function of Maternal Drinking and Smoking, in Currents in Alcoholism, Vol 5, Galanter, M., Ed.  Grun % Stratton, New York, 1979, 359.
68. Landessman-Dwyer, S., Ragozin, A. S., and Little, R. E.  Behavioral Correlates of Prenatal Aocohol Exposure:  A Four-Year Follow-Up Study.  Neurobehav. Toxicol. Teratol, 3: 187, 1981.
69. Dunn, H. G., McBurney A. K., Ingram, S., and Hunter, C.M.  Maternal Cigarette Smoking during Pregnancy and the Child's Subsequent Developement. 11. Neurological and Intellectual Maturation to the Age of 6.5 Years.  Can. J. Public Health., 68, 43, 1977.
70. Denson, R., Nanson, J. L., and McWatters, M. A.  Hyperkinesis and Maternal Smoking.  Can. Psychiatr. Assoc. J. 20, 183, 1975.

[Top]