Effects on birthweight of alcohol and caffeine consumption in smoking women.

STUDY OBJECTIVE--Previous work found no effect on birthweight of alcohol and caffeine consumption in non-smokers but such an effect was found in smokers. This report investigates further the effects on birthweight of alcohol and caffeine at three stages of pregnancy in smoking women. DESIGN--This was a prospective population study. SETTING--District general hospital in inner London. PARTICIPANTS--Out of 1309 women who completed all pregnancy interviews, 895 were excluded because they did not smoke, leaving a sample of 414 smokers. MEASUREMENTS AND MAIN RESULTS--Number and brand of cigarettes smoked, and quantity of alcohol and caffeine consumed were obtained by interview at booking, 28, and 36 weeks gestation. Birthweight was corrected for gestation and adjusted for maternal height, sex of infant and parity. The effect on birthweight of alcohol consumption was not explained by the amount smoked in terms of quantity and yield. Similarly the effect of caffeine was independent of smoking. When alcohol, caffeine, and smoking were analysed together, alcohol and caffeine were both associated with reductions in birthweight. Alcohol was associated with a reduction of up to 8% after adjusting for tobacco and caffeine intake, and caffeine was associated with a reduction of up to 6.5% after adjusting for tobacco and alcohol intake. Women who at booking were heavy smokers (greater than or equal to 13 cigarettes/day or greater than or equal to 15 mg carbon monoxide/cigarette), heavy drinkers (greater than or equal to 100 g/week alcohol), and had high caffeine intake (greater than or equal to 2801 mg/week) had a predicted reduction in mean birthweight of 18% (95% CI 11% to 24%). CONCLUSIONS--It is well known that women who smoke in pregnancy have smaller babies than non-smokers. Our study suggests that if these women also drink alcohol and high quantities of caffeine then the risk of poor fetal growth is increased even further.     

Evidence for compensation in smokers of low yield cigarettes

To determine the relation of smoking low yield cigarettes (tar yield less than 15.0 mg and nicotine yield less than 1.0 mg per cigarette) to the number of cigarettes smoked per day, we analysed information provided on self-administered questionnaires by 7706 current, regular cigarette smokers. The mean age at starting to smoke and the mean number of years of smoking were not consistently different in smokers of low yield compared with smokers of high yield cigarettes. In contrast, at all ages in both men and women, smokers of low yield cigarettes smoked significantly more cigarettes per day than smokers of high yield cigarettes. The differences in the number of cigarettes smoked per day between smokers of low and high yield cigarettes were small--about 3 cigarettes per day in men and about 1 1/2 cigarettes per day in women. However, these small differences might translate to the smoking of as many as one billion more packs of cigarettes per year in the United States alone. The potential beneficial effect of the smoking of cigarettes whose yield per cigarette is lower must be weighed against a possible adverse effect of the smoking of more cigarettes if the relation between smoking low yield cigarettes and smoking more cigarettes is causal.     

Influence of maternal active and passive smoking during pregnancy on birthweight in newborns

Many studies have documented a strong association of active smoking during pregnancy with fetal growth retardation. Increasing interest has also been focused on whether there is an association between exposure of pregnant women to environmental tobacco smoke (ETS) and low birthweight of their babies. In the intervention controlled study "Healthy Pregnancy--Healthy Child", mothers after delivery were interviewed by medical students who collected data about their smoking and nutrition. Students were also trained to stimulate non-smoking behaviour and to explain the risks related to smoking and exposure to ETS. Data from 1147 mothers after delivery were collected but only single births were included in the analysis of birthweight. In our study, 63.4% women never smoked and 32.2% women reported they had stopped smoking either before pregnancy or during the first trimester. Only 4.4% of mothers (n = 50) smoked during the whole pregnancy. Women with the history of smoking were exposed to ETS more often than mothers who never smoked (51.6% vs 17.4%; p < 0.001). The number of heavily exposed both at home and workplaces was more than twice higher among former smokers compared with never smokers (22.4% versus 9.4%, p < 0.01). The average birthweight of babies born to women who had stopped smoking was higher than that born to never smokers. The average birthweight of babies born to women who smoked during pregnancy was lower by 119 g and 171 g than that of the babies born to never smokers and former smokers, respectively. When pre-term neonates were excluded, differences in birthweight between babies born to never smokers and either formerly smoking or still smoking mothers were slightly lower. The greatest effect of ETS exposure on birthweight was recorded in never smoking mothers; an average reduction in birthweight was 88 g. A strong dose-effect was observed; in mothers heavily exposed to ETS both at home and at work, the babies' birthweight was lower by 189 g in comparison with the group of non-exposed, never smoking mothers and even by 70 g compared with mothers smoking during pregnancy.     

The influence of maternal cigarette smoking, snuff use and passive smoking on pregnancy outcomes: the Birth To Ten Study

This article describes the patterns and effects of maternal snuff use, cigarette smoking and exposure to environmental tobacco smoke during pregnancy on birthweight and gestational age, in women living in Johannesburg and Soweto in 1990. A cohort of 1593 women with singleton live births provided information about their own and household members' usage of tobacco products during pregnancy. The women completed a questionnaire while attending antenatal services. Data on gestational age and birthweight were obtained from birth records. Women who smoked cigarettes or used snuff during pregnancy accounted for 6.1% and 7.5% of the study population respectively. The mean birthweight of non-tobacco users was 3148 g [95% CI 3123, 3173] and that of the smokers 2982 g [95% CI 2875, 3090], resulting in a significantly lower mean birthweight of 165 g for babies of smoking mothers (P = 0.005). In contrast, women using snuff gave birth to infants with a mean birthweight of 3118 g [95% CI 3043, 3192], which is a non-significant (P = 0.52) decrease (29.4 g) in their infants' birthweights compared with those not using tobacco. A linear regression analysis identified short gestational age, female infant, a mother without hypertension during pregnancy, coloured (mixed racial ancestry), and Asian infants compared with black infants, lower parity, less than 12 years of education and smoking cigarettes as significant predictors of low birthweight, while the use of snuff during pregnancy was not associated with low birthweight. The snuff users, however, had a significant shorter gestational age than the other two groups of women. The birthweight reduction adjusted for possible confounders was 137 g [95% CI 26.6, 247.3 (P = 0.015)] for cigarette smokers and 17.1 g [95% CI -69.5, -102.7, P = 0.69] for snuff users respectively, compared with the birthweight of non-tobacco users. Among women who did not smoke cigarettes or use snuff, exposure to environmental tobacco smoke did not result in significant effects on the birthweight of their infants. In conclusion, infants of cigarette smokers had significantly lower birthweights than those of non-tobacco users or snuff users who are exposed to nicotine during pregnancy. Passive smoking did not affect birthweight significantly in this population.     

Adolescent smoking in pregnancy and birth outcomes

INTRODUCTION: Cigarette smoking amongst pregnant adolescents is a preventable risk factor associated with low birthweight (<2,500 g), preterm birth (<37 weeks) and infant mortality. The aim of this study was to compare birth outcomes of adolescents who smoke during pregnancy with those who do not and to construct their birthweight-for-gestational-age curves. METHODS: A retrospective cohort analysis of 534 adolescents (10 cigarettes daily had babies with larger birthweight reduction (P = 0.001). CONCLUSION: Almost half of all adolescents smoked during their pregnancy. Birthweight-for-gestational-age curves of smoking adolescents showed a marked fall-off in weight from 36 weeks of gestation, and at least 10% of adolescent smokers showed fetal growth restriction from before 32 weeks of gestation.     

Nicotine yield and measures of cigarette smoke exposure in a large population: are lower-yield cigarettes safer?

We examined the relationship of machine-estimated nicotine yield by cigarette brand with the level of cigarette consumption and two biochemical measures of smoke exposure (expired-air carbon monoxide and plasma thiocyanate) in a large, population-based sample of smokers (N = 713). The lower the nicotine yield of the cigarette, the greater the number of cigarettes smoked per day. Prior to adjusting for number of cigarettes smoked per day, nicotine yield was not related to the actual measures of smoke exposure. Smokers of ultralow-yield cigarettes had laboratory tests of smoke exposure which were not significantly different from those of smokers of higher-yield brands. Only after adjustment for number of cigarettes smoked per day did nicotine yield become significantly related to expired-air carbon monoxide and to plasma thiocyanate. In multivariate analysis, the number of cigarettes smoked per day accounted for 28 per cent and 22 per cent of the variance in observed expired-air carbon monoxide and plasma thiocyanate levels, respectively, whereas nicotine yield accounted for only 1 per cent and 2 per cent of the variance, respectively. The relative lack of an effect of nicotine yield on the biochemical measure appears to be due to the fact that smokers of lower nicotine brands smoked more cigarettes per day, thereby compensating for reduced delivery of smoke products. Our data do not support the concept that ultralow-yield cigarettes are less hazardous than others. Machine estimates suggesting low nicotine yield underrepresent actual human consumption of harmful cigarette constituents.     

ALCOHOL CONSUMPTION,CIGARETTE SMOKING AND FETAL OUTCOME IN VICTORIA, 1985

The aims of this study were to document the extent of cigarette smoking and alcohol consumption by Victorian women during pregnancy and relate the use of cigarettes and alcohol to various measures of pregnancy outcome. The study found that 24 per cent of women smoked during pregnancy and smoking was more common amongst younger women; 99.5 per cent of women drank, on average, less than two standard drinks per day and older women were more likely to be drinkers than younger women; 3.6 per cent of women reported at least one episode of binge drinking during pregnancy. There was an increasing trend in the proportion of low birthweight (>2500g) infants with increasing use of tobacco and a dose-dependent reduction in mean birthweight. Drinkers were less likely to have a pre-term or low birthweight infant than abstainers and babies born to drinkers had a higher mean birthweight than babies born to abstainers. The results of our study did not suggest that drinkers were at increased risk of delivering an infant with a congenital malformation, however heavy drinking was very uncommon in the studied population.     

Smoking habits and blood carbon monoxide levels

The carboxyhemoglobin concentrations (COHb) of 97 meat porters, 77 office workers, and 200 pregnant women have been determined. Individuals were questioned on smoking habits including numbers normally smoked per day, numbers already smoked on day of sampling, and time since last cigarette. The number of cigarettes smoked per day appears to allow the best prediction of COHb concentration. Individuals whose occupation involved them in physical exertion (meat porters) accumulated less carbon monoxide (CO) for numbers of cigarettes smoked per day than individuals smoking whilst sedentary. Pregnant women were seen to accumulate CO in a similar way to the active meat porters. In all groups, smokers had significantly higher COHb concentrations than nonsmokers. The effects of activity on CO uptake and elimination are discussed in relation to cigarette smoking, and it is suggested that the effect of activity on COHb is related more to elimination in the nonsmoking periods rather than uptake in the smoking periods.     

Demographics and cigarette smoking among women

BACKGROUND. A population-based sample of 893 white women ages 25 to 59 years from five San Francisco, California, Bay Area counties were queried about their demographic characteristics, height, reported weight at age 25, cigarette smoking history, and oral contraceptive and sunscreen use. METHODS. Multiple logistic regression techniques were used to analyze the data. Forty-three percent of the women in the sample had never smoked more than 100 cigarettes, while 27% were current and 30% were former smokers. Separated or divorced women were more likely to have ever smoked. RESULTS. Women who were less educated, single, separated, or divorced or had smoked between 10 and 30 cigarettes per day were less likely to quit smoking. Women with less education and a longer history of smoking smoked more cigarettes per day. Women who had never smoked were more likely to use sunscreen and to report their weight as slightly less at age 25 than were smokers.     

Serum bilirubin concentration in a Belgian population: the association with smoking status and type of cigarettes

BACKGROUND: The endogenous antioxidant serum bilirubin may scavenge free radical species from cigarette smoke. Smokers are expected to have lower serum bilirubin levels than never smokers, but this has never been evaluated in a random population sample of women and men. In addition, in vitro studies indicate that filter cigarette smoke might enhance bilirubin oxidation more than non-filter cigarette smoke. METHODS: In this paper, data were analysed from the Belgian Interuniversity Research on Nutrition and Health (BIRNH) study. We investigated the association of smoking and type of cigarettes with serum bilirubin concentrations in men and women using multiple regression models taking into account differences in baseline and smoking characteristics. RESULTS: In men, current smokers had lower crude and adjusted serum bilirubin concentrations compared with never smokers (P = 0.0001). For women, the association between smoking and serum bilirubin concentrations adjusted for age was in the same direction as for men, but did not reach statistical significance. Male former smokers had serum bilirubin concentrations in between those of current smokers and never smokers, while female former smokers had even higher (+ 0.50 micromol/l) serum bilirubin concentrations than never smokers. Male subjects smoking filter cigarettes showed a higher serum bilirubin concentration than those smoking cigarettes without a filter (adjusted difference: 0.49 micromol/l; P = 0.03). The duration of smoking was inversely and significantly related to serum bilirubin concentrations (P = 0.0003). CONCLUSION: Smoking may lower serum bilirubin concentrations in men, especially in those smoking non-filter cigarettes. The duration of smoking is a more important determinant for serum bilirubin concentrations than the number of cigarettes smoked per day, which may indicate the cumulative negative effects of smoking on the endogenous antioxidant system. Results for females pointed in the same direction, but were less clear, possibly due to low numbers of smoking women, who were largely young and smoked mainly filter cigarettes for a shorter period of time.     

Low birthweight, preterm births and intrauterine growth retardation in relation to maternal smoking

The association between the intensity and duration of cigarette smoking during pregnancy and the frequency of low birthweight, preterm births and intrauterine growth retardation was investigated in a historical cohort. All 5166 livebirths occurring in the city of Pelotas, Brazil, during 1993 were identified and mothers interviewed soon after delivery. Children whose mothers smoked during pregnancy had a birthweight 142 g lower than those of non-smoking mothers. The odds ratio for low birthweight among children of smokers was 1.59 [95% CI 1.30–1.95]. There was no association between smoking and preterm delivery assessed by the Dubowitz score. In relation to intrauterine growth retardation, smoking was associated with an odds ratio of 2.07 [95% CI 1.69–2.53]. There was a direct dose–response association between the number of cigarettes smoked and the risk of growth retardation. Women whose partner smoked were also at higher risk of having a child with growth retardation. All the above results were adjusted for confounding factors. The effect of maternal smoking on low birthweight seems to be attributable to intrauterine growth retardation rather than preterm delivery.     

Spontaneous cigarette brand switching: consequences for nicotine and carbon monoxide exposure.

A group of smokers who had participated in smoking-related studies three to six years earlier were re-studied to assess changes in their smoking practices. Individuals who smoked the same brands of cigarettes showed no change in plasma cotinine (reflecting exposure to nicotine) or expired carbon monoxide (CO) concentration. Those who switched to cigarettes of lower nicotine yield (average decrease 38 per cent) showed reduced plasma cotinine concentrations, due primarily to smoking fewer cigarettes per day. The intake of nicotine per cigarette was not different. Subjects who smoked cigarettes of higher yield (102 per cent increase) had higher cotinine and CO levels, due to greater intake per cigarette.     

Risks of lung cancer, chronic bronchitis, ischaemic heart disease, and stroke in relation to type of cigarette smoked.

In a case control study of over 12 000 inpatients aged 35-74, risk of lung cancer, chronic bronchitis, and, particularly in those aged 35-54, ischaemic heart disease was positively associated with the number of manufactured cigarettes smoked daily and was negatively associated with long term giving up. Risk of stroke was not clearly related to smoking. Among manufactured cigarette smokers, lung cancer risk tended to be lowest in those who had always smoked filter cigarettes. This pattern was, however, evident only in men who additionally smoked pipes, cigars or handrolled cigarettes and in women, not being seen in men who smoked only manufactured cigarettes. Risk of lung cancer was not clearly related to time of switch to filter cigarettes. A markedly lower risk of chronic bronchitis was seen in men, but not women, who smoked filter rather than plain cigarettes. Heart disease risk did not vary by type of cigarette smoked 10 years before admission, but, compared with those who had never smoked filter cigarettes, those who had ever smoked filter cigarettes had a higher risk in men and a lower risk in younger women. Compared with the general population, markedly more controls were ex-smokers, suggesting incipient disease, whether or not smoking related, may alter smoking habits, thus affecting the interpretability of the findings. Control smokers were also relatively much more likely to report smoking plain cigarettes than expected. This comparison, not made in other studies relating risk to type of cigarette smoked, indicates that great care must be taken in verifying validity of reported smoking habits. While our findings are compatible with other evidence that risk of lung cancer and chronic bronchitis is probably reduced by switching from plain to filter cigarettes, they underline the difficulties in obtaining valid evidence from epidemiological studies.     

Reinterpreting the effects of maternal smoking on infant birthweight and perinatal mortality: a multivariate approach to birthweight standardization.

Infants of women who smoke during pregnancy have lower birthweights and have been observed to have higher rates of perinatal mortality than infants of non-smokers. It is not clear whether this increased risk of mortality is due to an excess of small births among smokers or to an independent effect of smoking. Although infants of smokers have overall higher mortality rates than non-smokers, low birthweight (< 2500 g) infants of smokers have lower mortality rates than low birthweight infants of non-smokers. However, comparison of birthweight-specific mortality between two groups is problematic when there are differences in the birthweight distributions. Methods that have been developed to standardize for these differences by comparing mortality rates relative to their own mean do not allow for simultaneous control of confounding variables. Using data from over 13,000 births of women who participated in a prepaid health care plan we present a method to standardize for birthweight while adjusting for variables that may confound the relationship between maternal smoking and perinatal mortality. After controlling for race, maternal age, education, parity, and number of cigarettes smoked, we found that 85% of the increased mortality due to smoking was attributable to an excess of small births in the birthweight distribution of offspring of smoking mothers, while 15% was due to higher birthweight-specific mortality at almost all standardized birthweights. Contrary to previous reports, we found that low birthweight infants of smoking mothers are at higher risk of perinatal mortality if a population-specific standard for birthweight is used.     

"Tar" and nicotine content of cigarette smoke in relation to death rates.

Over 1,000,000 men and women who enrolled in an epidemiological study in 1959–1960 were (with few exceptions) traced for 12 years. They all answered questionnaires on cigarette smoking and various other factors at time of enrollment; and survivors answered repeat questionnaires on three later occasions. In this analysis, cigarette smokers were classified by the amount of tar and nicotine delivered by the brand they usually smoked at the start of each of two 6-year periods. Among subjects who smoked the same number of cigarettes a day, total death rates, death rates from coronary heart disease, and death rates from lung cancer were somewhat lower for those who smoked “low” tar-nicotine cigarettes than for those who smoked “high” tar-nicotine cigarettes. The death rates of subjects who smoked “low” tar-nicotine cigarettes were far higher than the death rates of subjects who never smoked regularly.     

Cigarette smoking and male lung cancer in an area of very high incidence. I. Report of a case-control study in the West of Scotland.

Altogether 656 male lung cancer cases and 1312 age and sex matched controls were interviewed between 1976 and 1981 in a case-control study of cigarette smoking habits and lung cancer in Glasgow and the West of Scotland, an area with the highest recorded incidence in the world. The relative risk of lung cancer increased significantly for smokers whose consumption was below 20 cigarettes per day but did not rise significantly in those who smoked more than 20 cigarettes per day. Other smoking characteristics such as inhalation and tar yields of brands smoked did not explain this finding. Additionally, the relative risks observed at all levels of cigarette consumption were low in comparison with those in the published literature. By constructing an index of cigarette exposure which included the tar yields of brands smoked, an assessment of the risk of lung cancer in relation to tar exposure independent of amount smoked was derived. Only in smokers of less than 15 cigarettes per day was there a statistically significant reduction in risk of lung cancer associated with lower levels of tar yield.     

A trial of health education aimed to reduce cigarette smoking among pregnant women

Three hundred and forty-six women who reported smoking one or more cigarettes per day prior to the 20th week of gestation were recruited into a trial of health educational counselling to stop or reduce cigarette smoking. Counselling was begun at the first prenatal visit and then continued subsequently in the home. Among the 319 women included in analysis, at first follow-up visit those who received counselling smoked 1.7 fewer cigarettes a day than control women (P less than 0.05) and 10.4% had stopped smoking, compared to 5.4% in the control group (NS). Similar but not significant differences were noted at the end of pregnancy. Study effects were limited to the 284 women smoking five or more cigarettes a day at booking. This report refers primarily to them. At first follow-up visit the proportion of such women in the counselled group who ceased smoking (9.3%) was significantly greater than in the control group (2.6%; P less than 0.05). The magnitude of this difference persisted through late pregnancy (11.8% vs. 4.3%; NS) and delivery (10.6% vs. 4.7%; NS). The differences between counselled women and controls in numbers of cigarettes reported smoked at first and last prenatal follow-up visits (2.4 and 2.1) and at delivery (2.0) were all statistically significant. While there was no effect of counselling on either serum thiocyanate or end expiratory carbon monoxide, the counselled group gained slightly more weight than controls during the study (0.47 vs. 0.44 kg per week among controls; NS), and their infants had modestly higher birthweight (44 g; NS).     

Does maternal tobacco smoking modify the effect of alcohol on fetal growth?

Smoking and drinking habits were registered by a self-administered questionnaire in 36th week of gestation in 11,698 pregnant women, more than 80 percent of all such women in two Danish cities 1984-87. Alcohol consumption of 120 g/week or more was associated with a greater reduction in the average birthweight in the babies of smokers than of non-smokers (about 40 grams for the non-smokers and about 200 grams for the smokers). This is particularly striking considering that the average birthweight for smokers is lower than for non-smokers. A birthweight difference of more than 500 grams was found between babies of mothers who neither smoked nor drank and mothers who smoked and drank heavily. Our data suggest that women's smoking habits should be taken into consideration when giving pregnant women advice about drinking.     

Maternal smoking and congenital malformations: an epidemiological study.

In a case-control study undertaken in several hospitals in Connecticut, it was found that women who reported smoking more than 20 cigarettes a day during pregnancy had a relative risk of about 1.6 for congenital malformations in the offspring of that pregnancy compared with women who said they had not smoked at all during pregnancy. However, there was no significant increase in risk among women who reported smoking 20 or fewer cigarettes a day during pregnancy compared with those who said they had not smoked at all during pregnancy. The higher risk among moderate and heavy smokers could not be attributed to any of the potentially confounding variables considered in this study; furthermore, it was specific to smoking during pregnancy rather than before pregnancy, and increased with the average amount smoked a day. Nevertheless, because the increase in risk was modest, because response bias could exist in a study of this type, and because no other studies have examined in detail the smoking-congenital malformation hypothesis, further research is needed to determine whether the relationship between maternal smoking and congenital malformations in offspring is causal.     

The influence of active maternal smoking during pregnancy on birth weights in Cyprus

Cigarette smoking during pregnancy has been causally associated with an increased risk of both intrauterine growth retardation and preterm delivery but most strongly with low birth weight. No such study to date had ever dealt with the Cypriot population. In interviews with their gynaecologists 65,530 pregnant women were asked between January 1990 and August 1996 to answer two questions, whether they had been smoking before and whether they had been smoking during pregnancy. Data from 59,014 births were considered to have valid birth weight data for this investigation. In 81.2% of the cases the mother explicitly declared that she had neither smoked before or during pregnancy whereas in 1.4% of the cases the mother said that she had smoked both before and during pregnancy and in 1.4% of the cases the mother said that she had smoked before but not during pregnancy. Finally, in 15.3% of the cases no answer to "smoking question" was given, whereas in 0.7% of the cases the answer that was given was deemed as not clear. The average birth weight of babies born to women who had stopped smoking was insignificantly different than that of those born to never smokers. The average birth weight of babies born to women who smoked during pregnancy was lower compared to babies born to non smokers' babies by 92 grams, 66 grams, and 109 grams for all babies, singleton boys and singleton girls respectively. The greatest effect to their mean birth weights was observed in babies whose mothers did not answer the question on smoking. Their babies had birth weights lower than non smokers' babies by 203 grams, 197 grams, and 201 grams for all babies, singleton boys and singleton girls respectively.