Smoking and cycle control among oral contraceptive users

OBJECTIVE

Because cigarette smoking has a variety of antiestrogenic actions, we investigated the possibility that smoking may adversely affect spotting and bleeding among women using oral contraceptives.

STUDY DESIGN

Three open-label, randomized clinical trials involving 16,506 cycles among 2956 oral contraceptive users were performed.

RESULTS

Smokers reported a consistently higher frequency of spotting or bleeding than did nonsmokers. After recency and consistency of oral contraceptive use and progestin component were controlled for, smokers were, on average, 47% more likely to have spotting or bleeding than nonsmokers were over six cycles of oral contraceptive use, with higher levels of smoking associated with a greater frequency of spotting or bleeding. By the sixth cycle women who smoked > or = 16 cigarettes per day were almost three times more likely to have spotting or bleeding than were nonsmokers.

CONCLUSION

Cigarette smoking adversely affects cycle control among oral contraceptive users, possibly by increasing estrogen catabolism. Although these findings also raise the possibility that oral contraceptive efficacy may also be impaired in smokers, an immediate concern is that oral contraceptive users who have spotting and bleeding are more likely to discontinue their use, placing them at risk of unintended pregnancy.

Haemostasis profile in smoking and nonsmoking women taking low-dose oral contraceptives

The effects of oral contraceptives on coagulation in 258 nonsmoking and in 190 smoking women were determined. In smokers and in nonsmokers taking oral contraceptives, fibrinogen and fibrinopeptide A concentrations were higher than in oral contraceptive nonusers. In nonsmokers, oral contraceptives increased antithrombin III activity. The effects on coagulation of oral contraceptives with a different ethinylestradiol content (from 35 mcg to 20 mcg) were then evaluated in 333 of these women. The biggest changes in coagulation were observed in smokers taking the preparation with the highest estrogen content. Reduction of the ethinylestradiol dose caused a decrease of the changes in coagulation induced by oral contraceptives both in smokers and nonsmokers. These results might suggest that during oral contraception the coagulation system is affected mainly in smokers and that the decrease of the estrogen dose might lower the effects of the association of smoking and oral contraception on coagulation.

The effect of smoking during pregnancy on the incidence of low birth weight among Chinese parturients

The incidence and effect of smoking in Chinese parturients are not well known. In a retrospective case-controlled study of 213 patients who smoked during pregnancy, it was found that the incidence of low birth-weight was doubled. On average the babies were smaller by 200 g, shorter by 1 cm and the head circumference was smaller by 0.3 cm. These anthropometric deficits may have significant long-term effects. Although the incidence of smoking in Chinese parturients is low (2%), the rising trend in recent years should prompt all physicians to advise expectant mothers to avoid smoking before and during pregnancy.

A case-control study of paternal smoking and birth defects

Although the influence of paternal smoking on birth defects is of great public interest, epidemiological evidence concerning this potential relationship is extremely limited. A stratified random sample of 29 hospitals in the Shanghai Municipality, China, was used to select 1012 birth defects cases and controls. Mothers of the cases and controls were interviewed in the hospitals from October 1986 to September 1987. A modest relationship between paternal smoking and overall birth defects in offspring was identified [odds ratio (OR) = 1.21, 95% confidence interval (CI): 1.01-1.45]. More markedly elevated risks were identified for anencephalus (OR = 2.1), spina bifida (OR = 1.9), pigmentary anomalies of the skin (OR = 3.3) and varus/valgus deformities of the feet (OR = 1.8). Our analysis also shows that paternal smoking is more likely to be associated with multiple rather than isolated malformations. A paternally-mediated effect of smoking on birth defects is suggested and further studies are encouraged.

Very high collagen increase in placentae of smoking mothers

In 55 placentae, collected at term from clinically normal pregnancies, hydroxyproline was assayed. Thirty were from mothers who smoke and 25 from nonsmokers. In placentae of smokers, hydroxyproline concentration was 42.77 +/- 8.77 micrograms/mg of tissue and in these of nonsmokers 22.52 +/- 7.46 micrograms/mg. Such high a difference discloses a large increment in placental collagen production in smokers, which may account for some of the noxious effects of tobacco on pregnancy.

Smoking, the oral contraceptive pill, and Crohn's disease

Both cigarette smoking and the oral contraceptive pill have been implicated as aggravating factors in Crohn's disease. Based upon the recent demonstration of multifocal gastrointestinal infarction in Crohn's disease, a possible pathogenic mechanism for this condition, we propose how smoking and the oral contraceptive pill may potentiate a tendency for focal thrombosis and hence exacerbate the activity of Crohn's disease.

[Smoking effects on pregnancy]

A review of the literature on the effects of smoking on the health during pregnancy has been undertaken. Recent data on smoking patterns in the USA are listed and the gravity of the effects of passive smoking is brought out. The review of some new data shows that smoking in pregnancy increases the risk of fetal and infant mortality, and that the risk is dose-related. The factors by means of which smoking leads to the increase of fetal and infant mortality are given and include: low birthweight, premature rupture of membranes, abruptio placentae, placenta previa and tubal pregnancy.

An epidemiologic survey of cardiovascular disease in women taking oral contraceptives

Earlier epidemiologic studies have indicated an increase in mortality from certain cardiovascular diseases in young women associated with the use of oral contraceptives. However, since these studies were conducted, newer oral contraceptives containing less estrogen and progestogen have been widely adopted. In addition, an increasing majority of oral contraceptive use is by women under the age of 30 years. Early results from a new case-control study suggest the possibility that the risk of myocardial infarction associated with oral contraceptive use is now lower than in the past, although the previously observed small increase in the risk of subarachnoid hemorrhage appears to be unchanged.

The antiestrogenic effect of cigarette smoking in women

Epidemiologic results indicate that women who smoke cigarettes are relatively estrogen-deficient. Smokers have an early natural menopause, a lowered risk of cancer of the endometrium, and an increased risk of some osteoporotic fractures. Moreover, women who smoke may have a reduced risk of uterine fibroids, endometriosis, hyperemesis gravidarum, and benign breast disease. Several possible mechanisms for these effects have been identified. Smoking does not appear to be clearly related to estradiol levels, at least in postmenopausal women, although levels of adrenal androgens are increased. Moreover, smoking appears to alter the metabolism of estradiol, leading to enhanced formation of the inactive catechol estrogens.

Sex-difference and the effects of smoking and oral contraceptive steroids on the kinetics of diflunisal

The single dose pharmacokinetics of diflunisal were studied in 4 groups of 6 young volunteers: control men, control women, women taking low estrogen oral contraceptive steroids (OCS), and women smokers (10-20 cigarettes day). The plasma clearance of diflunisal was significantly higher in men (0.169 ml.min-1.kg-1) and in women on OCS (0.165 ml.min-1.kg-1) as compared to control women (0.108 ml.min-1.kg-1). Partial metabolic clearances of diflunisal by the three conjugative pathways (phenolic and acyl glucuronide formation, sulphate conjugation) were all increased in men and women OCS users as compared to control women. Statistically significant increases, however, were only observed for the partial metabolic clearance of diflunisal by phenolic glucuronidation between men and women (2.91 vs. 1.85 ml.min-1 respectively), and for the partial clearance by acyl glucuronidation between OCS users and control women (4.81 vs. 3.01 ml.min-1 respectively). Smoking resulted in a moderate increase (35%) in plasma diflunisal clearance. However, a significant reduction in total urinary recovery of diflunisal and its glucuronide and sulphate conjugates was found in smokers (70.5% in smokers as compared to 84.2-87.2% in the 3 other study groups). Consequently, smoking may have induced hydroxylation, a minor oxidative metabolic pathway of diflunisal recently discovered in man.

Smoking does affect fecundity

A total of 2198 mothers were interviewed at the 20th week of pregnancy and their smoking habits before pregnancy and the time from discontinuation of contraception to the beginning of the pregnancy were registered. This information was used to investigate whether smoking affects conception delay; i.e., fecundity and a multifactorial analysis were used. The longer the conception delay, the more significant was the deleterious effect of even light smoking, the odds ratio shifting from 1.1 at 6 months to 3.2 at 18 months. The effect of smoking on fecundity seemed to be mostly dose-dependent. In mothers becoming successfully pregnant in 12 months, both maternal and paternal smoking increased the risk of conception delay (OR 1.5 and 1.3), and the effect was potentiated by increasing age (OR 2.3 and 1.6). In addition to smoking, previous recurrent spontaneous abortions were also associated with fecundity.

Smoking, maternal age, fetal growth, and gestational age at delivery

The relationship between smoking and maternal age and their combined effects on birth weight, intrauterine growth retardation, and preterm delivery were studied. Smoking lowers birth weight both by decreasing fetal growth and by lowering gestational age at delivery. However, the effect of smoking on both fetal growth and gestational age is significantly greater as maternal age advances. In a multiple logistic regression model adjusting for race, parity, marital status, maternal weight, weight gain, and alcohol use, smoking was associated with a fivefold increased risk of growth retardation in women older than 35 but less than a twofold increased risk in women younger than 17. Smoking reduced birth weight by 134 gm in young women but 301 gm in women older than 35. Smoking in older women also was associated with more instances of preterm delivery and a lower mean gestational age when compared to women 25 or younger.

Morphometric differences between the placental vasculature of non-smokers, smokers and ex-smokers

The aim of this study was to determine whether cigarette smoking during pregnancy has an adverse effect upon the placenta's capacity for gaseous exchange. Using recently developed stereological techniques, in conjunction with perfusion fixation, computer-assisted measurements were made on the placentas of 15 non-smokers, 15 moderate smokers, 15 heavy smokers and 13 ex-smokers, 7 of whom stopped smoking during the course of the pregnancy. Compared with the placentas of non-smokers and of those who stopped before pregnancy, it was found that the placentas of smokers and of those who stopped after conception exhibited a reduced capillary volume fraction, and an increased thickness of the villous membrane. Although they must impair gaseous exchange across the placenta, these changes were less severe than suggested by previously published reports. Nonetheless it is clear that in order to prevent these changes women should stop smoking before conception rather than during the course of a pregnancy.

Cigarette smoking in pregnancy results in marked decrease in maternal hCG and oestradiol levels

We have examined serum levels of oestradiol (E2), sex-hormone binding globulin (SHBG) and human chorionic gonadotrophin (hCG) during early pregnancy in relation to smoking status at the time of sampling in a series of 147 women. Smoking was associated with significantly depressed serum levels of E2, SHBG and hCG: in smokers, E2 levels were on average 17.6% lower (P = 0.037), SHBG levels were 12.4% lower (P = 0.15), and hCG levels were 21.5% lower (P = 0.044). There appeared to be a steady decline in these values with increasing cigarette consumption. These lower hormone levels in smokers may explain certain adverse effects of smoking in pregnancy.

Maternal smoking in relation to the incidence of early neonatal jaundice

A case-control study was carried out to investigate the association between maternal smoking during pregnancy and the risk of early neonatal jaundice. A total of 1,569 cases of neonatal jaundice (2.7% of all singleton births) were identified from the 1984 Washington State birth certificates as having a bilirubin level greater than 10 mg/dl within the first 2 days of life. 2,336 nonjaundiced infants were randomly selected to serve as controls. Information regarding smoking during pregnancy was also obtained from the birth certificates. After excluding infants with known risk factors for neonatal jaundice, 912 cases and 1,752 controls were available for analyses. Infants whose mother smoked cigarettes during pregnancy were at lower risk of neonatal jaundice (odds ratio = 0.81; 95% confidence interval = 0.66-0.99) relative to infants of nonsmokers. This relative risk changed very little after adjusting separately for maternal age, infant's gender, number of prior pregnancies, number of prenatal visits, marital status and number of prior fetal deaths. There was suggestive evidence that this apparent protective effect may be operating only among normal and high-birth-weight infants.

Cigarette smoking and male reproduction

The effects of cigarette smoking on male reproduction were studied through measuring the serum estradiol (E2), prolactin (PRL), and total testosterone (T). Smoking men had higher levels of E2 and PRL but normal T compared to nonsmokers. Raised E2 and PRL may be among the mechanisms through which cigarette smoking impairs male reproduction.

Plasma reduced and total ascorbic acid in healthy women: effects of smoking and oral contraception

This is the first report of both reduced (RAA) and total (TAA) plasma ascorbic acid levels in women who smoke and are on oral contraception. 155 normal healthy subjects were investigated. A study questionnaire was completed including age, method of contraception, smoking status, and food intake at breakfast, prior to attending the clinic. Biochemical assays were promptly carried out without knowledge of subject's clinical or dietary status. One-way analysis of variance revealed that oral contraception per se, barrier or IUD methods have no effect on plasma ascorbic acid levels. The mean values (mg/dl +/- SD) for plasma RAA between smokers and nonsmokers were 0.512 +/- 0.241 and 0.601 +/- 0.263; and that for TAA were 0.565 +/- 0.232 and 0.682 +/- 0.231, respectively. Significant decreases in both plasma RAA (p less than 0.05) and TAA levels (p less than 0.001) were observed in smokers. Age was an interacting variable. No association of smoking or oral contraceptive use was seen with RAA or TAA levels among women less than 26 years, but decreases in both RAA and TAA levels were evident among smokers aged 26 years or older. The present study emphasizes the total exposure to smoking, e.g., pack years, is a significant confounding variable in the study of plasma ascorbic acid levels.

Maternal cigarette smoking: the effects on umbilical and uterine blood flow velocity

Maternal and fetal effects of smoking one cigarette were assessed in 15 healthy women at 36 to 41 weeks' gestation with no obstetric complications. It was found that smoking was associated with increases in maternal heart rate and blood pressure, but there was no significant change in the uterine artery vascular resistance as measured by means of the systolic/diastolic velocity ratio. There also was an increase in the fetal heart rate as well as a highly significant rise in the systolic/diastolic velocity ratio of the umbilical artery. The responses suggest that smoking causes a direct increase in the vascular resistance of the placenta from the fetal side. This resistance may impair oxygen exchange across the placenta and contribute to the increased perinatal morbidity associated with smoking.

Dynamics of estradiol and testosterone and seminal fluid indexes in smokers and nonsmokers

The serum levels of estradiol (E2) and testosterone (T), the metabolic clearance rates of estradiol (MCRE2) and testosterone (MCRT), and the production rates of estradiol and testosterone (PRE2) and (PRT) were examined in 22 male smokers and 21 male nonsmokers. Seminal fluid indexes (sperm count, % motility, grade of motility, and % of sperm with abnormal morphology) were also assessed. The mean E2 level and the mean PRE2 were significantly greater in smokers than in nonsmokers (P less than 0.001 and P less than 0.01, respectively); however, the means of MCRE2, MCRT, PRT, and T did not differ significantly in smokers compared to nonsmokers. No significant product-moment correlations were found between the various hormonal measures and the seminal fluid indexes in the overall sample. However, the smokers with sperm counts below the median sperm count of the sample had significantly higher mean levels of E2 and PRE2 than did the smokers with sperm counts above that median. Mechanisms that might mediate the greater PRE2 of smokers and a negative relationship between estradiol and sperm count are discussed.

Effect of cigarette smoking on cervical epithelial immunity: a mechanism for neoplastic change?

Langerhans' cells in cervical epithelium in colposcopic biopsy specimens were identified by immunocytochemical staining for S100 protein and T6 (CD1) antigen, and their density was quantified. Possible cofactors for the development of cervical neoplasia were examined for any effect on the cell counts per unit area. Current cigarette smoking was associated with a significant decrease in the Langerhans' cell population in both normal epithelium and lesions due to cervical intraepithelial neoplasia. Ex-smokers tended to have cell counts between those of smokers and non-smokers. There was a dose-response relation between number of cigarettes smoked daily and effect on cell counts. These findings of a local immunological effect of smoking on cervical epithelium may explain the means by which cigarette smoking contributes to the development of cervical neoplasia.

The influence of method of contraception and cigarette smoking on menstrual patterns

Self-perceived menstrual patterns have been investigated in a sample of 2115 women aged 18-49 years using a postal questionnaire. Seven aspects of 'abnormal' menstruation were defined: prolonged periods, heavy periods, frequent periods, irregular periods, intermenstrual bleeding, painful periods and severe premenstrual syndrome. Women who used oral contraceptives were less likely than other women to report any of the seven menstrual abnormalities except for intermenstrual bleeding and severe premenstrual tension. Women who used an intrauterine contraceptive device (IUCD) reported prolonged, heavy, and frequent periods and intermenstrual bleeding more often than other women, but they did not report painful periods with undue frequency. Women who had had a tubal sterilization generally reported menstrual patterns similar to, or slightly less favourable than, women using no contraception or contraceptive methods other than the pill or the IUCD. There was a significant association between smoking habits and each of the abnormal menstrual patterns except for severe premenstrual tension. In every case, the effect of smoking was unfavourable and in almost every case, current smokers reported the worst experience, with ex-smokers occupying an intermediate position. We believe that these data are of considerable clinical significance and that they offer a basis for a conservative approach to managing menstrual disorders in some women.

Smoking in pregnancy: effects of stopping at different stages

Of 4341 pregnant women, 3106 were non-smokers and 1235 were smokers at the start of pregnancy. Eighty-five had stopped smoking before 6 weeks gestation, 119 between 6 and 16 weeks, and 56 stopped after 16 weeks. A further 51 stopped temporarily and 924 smoked throughout pregnancy. The mean birthweight of the groups differed. There were also social and biological differences such as might partly explain birthweight variations so comparisons were repeated after allowing for these factors. Standardized mean birthweights were greater for all groups who stopped than for persistent smokers. Those who stopped before 6 weeks and between 6 and 16 weeks gestation had infants 217 and 213 g, respectively, heavier than the persistent smokers and similar to the non-smokers. Babies born to those who stopped after 16 weeks, or temporarily, were intermediate in weight. Appropriate advice is that stopping any time before 16 weeks is best, but stopping after this is still beneficial.

A prospective study of the relation between smoking and fertility

A prospective study of fertility was conducted from 1977 to 1982. Analysis of the relation between cigarette smoking and occurrence of a pregnancy was performed on 1887 couples. The actuarial pregnancy rate was 82.9% at the end of a year. Cigarette smoking by both members of the couple was found to be related to decreased fertility when this factor was considered alone. But after including all the confounding covariates in a Cox semi-proportional hazards model for survival data, no relationship remained between cigarette smoking and fertility. Odds ratios were respectively 0.86 (95% confidence interval: 0.63, 1.19) and 0.99 (0.85, 1.14) for women smoking and men smoking. This could suggest that the relationship found by other authors might be at least partly explained by a relation between cigarette smoking and other factors related to fertility.

The relationship between passive smoking and child health: methodologic criteria applied to prior studies

Most studies investigating the relationship between passive smoking and child health have found a significant effect on respiratory illness and lung function. The wide range of findings is based on diverse types of studies which use multiple criteria for respiratory illness, smoke exposure, and outcome variables. The aim of this review is to examine these studies in an attempt to focus attention on methodological criteria which relate to the strength of the association and likelihood of a causal relationship between passive smoking and child health. We examined 30 studies and judged their strength by examining (1) data collection, (2) surveillance bias, (3) definition of amount of smoking, (4) definition of illness, (5) detection bias, (6) outcome variables, and (7) control for confounding variables. Poor scores were noted in the use of "blinded" data collectors (37 percent of possible score), use of multiple specific outcome variables (51 percent), and definition of the quantity of smoking (56 percent). Good scores were noted in the detection of illnesses (98 percent), recall by study subjects of symptoms of illness (71 percent), control for confounding variables (81 percent), and definition of illnesses (86 percent). The range of scores for the studies was from 44 percent to 89 percent (of the total possible score). While a few well-designed studies demonstrate a significant effect of passive smoking on child health, most studies had significant design problems that prevent reliance on their conclusions. Thus, many questions remain, and future studies should consider important methodological standards to determine more accurately the effect of passive smoking on child health.

Maternal smoking and alcohol consumption as determinants of birth weight in an unselected study population

A prospective study was conducted to determine the effects of maternal smoking and alcohol consumption during pregnancy on the birth weight of fetuses in an unselected study population. Several confounding factors were taken into account. The main factors associated with an increase of birth weight of both sexes were gestational age at birth and parity. Both maternal smoking and maternal alcohol consumption during pregnancy had the effect of decreasing the birth weight of female fetuses, whereas smoking, but not alcohol, had a decreasing effect on birth weight of male and female fetuses.

Cigarette smoking and semen quality in men of reproductive age

The effect of cigarette smoking on conventional semen parameters was studied in voluntary men of reproductive age (n = 190). Special attention was focused on sperm motility and its quantitative and qualitative change in vitro during the observation period. The sperm output war normal in both smokers (n = 54) and non-smokers (n = 110), but semen volume was smaller (p less than 0.03) in heavy smokers (greater than 16 cigarettes/day) than non-smokers. In sperm morphology there was no difference between study groups. The only clear difference between men with different smoking habits was in the percentual change in the sperm motility during 24 hours. At the time of first examination, the sperm motility was better (p less than 0.02) in heavy smokers than those who smoked less than 16 cigarettes per day and the motility decreased more rapidly (p less than 0.007) in heavy smokers than non-smokers. The objectively measured initial mean velocities of the whole sperm population and of the progressive spermatozoa were slightly higher in subgroup of smokers than in non-smokers. The rapid decrease in the survival spermatozoa in smokers may be uneconomical and harmful in respect of fertility.

Adverse influences of alcohol, tobacco, and oral contraceptive use on cardiovascular risk factors during transition to adulthood

Risk factors for cardiovascular disease were measured in 990 young adults, aged 17-24 years, in a 1982-1983 survey of the biracial (black-white) community of Bogalusa, Louisiana. Even after controlling for age and obesity, several lifestyle factors (cigarette smoking, alcohol consumption, and oral contraceptive use) were independently related (p less than 0.05) to levels of serum lipids, lipoprotein cholesterol fractions, and blood pressure. Oral contraceptive use was associated with increased levels of both serum triglycerides (20 mg/dl, blacks; 25 mg/dl, whites) and low density lipoprotein (LDL) cholesterol (19 mg/dl, whites), and decreased levels of high density lipoprotein (HDL) cholesterol (-6 mg/dl, whites). Linear regression analyses also showed that cigarette smoking was associated with elevated levels of serum triglycerides (ranging from 15 to 26 mg/dl) and decreased levels of HDL cholesterol (ranging from -9 to -11 mg/dl) in white males and females. Although persons who smoked cigarettes were also likely to consume alcohol, alcohol intake in nonsmokers was positively associated with levels of serum triglycerides, LDL cholesterol, and very low density lipoprotein cholesterol in white males, and with blood pressure levels in black males. A statistically significant association between alcohol intake and HDL cholesterol levels (r = 0.24) was observed only in white females who did not smoke. These adverse influences of lifestyle factors on cardiovascular disease risk may provide a rational basis for intervention during adolescence and early adulthood.

Cigarette smoking and the risk of epithelial ovarian cancer

Cigarette smoking may affect each of the currently proposed mechanisms of ovarian carcinogenesis. Whether cigarette smoking has any effect on the development of ovarian cancer has not been adequately evaluated. To study this issue, the authors examined data from the Cancer and Steroid Hormone Study, a multicenter, case-control study of gynecologic cancers conducted between December 1, 1980, and December 31, 1982, in eight geographic areas of the United States. This analysis utilized data on 494 women with newly diagnosed epithelial ovarian cancer and 4,238 population-based control women 20-54 years of age. There was no association of epithelial ovarian cancer with dose of cigarette smoking, age smoking started, time since smoking started, or time since smoking last occurred. Simultaneous adjustment for age, parity, history of oral contraceptive use, and other potentially confounding factors did not alter these results.

Smoking, alpha 1-antitrypsin and decreased fertility in women

There is epidemiologic evidence that smoking by women is associated with decreased fertility. Little is known about the biological mechanism(s) that might underlie a direct association. The effect of smoking on genital secretions, including levels of alpha 1-antitrypsin (AlAT), has not been studied. Low midcycle levels of AlAT appear to favour fertility by facilitating sperm migration and/or penetration. Smoking increases serum levels of functional AlAT. Since AlAT is produced only in the liver, levels in other tissues may reflect serum levels. It is postulated that smoking-induced increases in serum AlAT result in higher levels of AlAT in genital secretions, including those at midcycle, thereby impeding fertility. Support of an effect of serum AlAT levels on fertility is provided by studies of AlAT deficient persons, in whom fertility seems to be enhanced. An adverse effect of smoking on fertility through an increase in genital tract AlAT levels would be reversible.

Cancer of the cervix uteri and vitamin A

The concentrations of retinol and beta carotene were measured in serum samples taken from 113 women with cervical cancer, 32 with invasive and 81 with pre-invasive disease, and compared with those from 226 age-matched control women. There was little difference in serum retinol levels between women with cancer of the cervix, at any stage, and the control women, after adjusting for potential confounding factors. Serum beta carotene concentrations were likewise similar in women with invasive disease and the controls. However mean beta carotene levels were significantly reduced in women with pre-invasive disease compared to the controls (221.3 cf. 291.6 micrograms l-1, P less than 0.05). This reduction was more evident amongst women with a diagnosis of carcinoma-in-situ (mean 213.1 micrograms l-1 than amongst those with severe dysplasia (mean 228.7 micrograms l-1. There is a negative trend between beta carotene and risk of pre-invasive disease which is of borderline significance. These data have also been used to investigate the effects of smoking and oral contraceptive usage on the serum levels of retinol and beta carotene. Both habits tend to increase retinol and decrease beta carotene concentrations.

Epidemiology of Crohn's Disease

Although our current understanding is limited, epidemiologic investigation of Crohn's disease holds great promise. Certain aspects of the epidemiology are clear. The incidence of Crohn's disease, which has increased over the past few decades, may have reached a plateau. The disease has its peak onset in early life, with a second peak among the elderly. It is more common in the developed countries and among Jews. Whether the disease is related to occupation, social class, marital status, stress, infection, diet, smoking, and oral contraceptives is less certain. This paper reviews the epidemiology of Crohn's disease and proposes areas in which further research is needed.

Cigarette smoking and its possible effects on sperm

The possible effects of cigarette smoking on sperm were evaluated by comparison of the quality of sperm from 103 smokers and 135 nonsmokers in a blind study. Smokers were found to possess significantly (P less than 0.001) decreased density (number) and motility of their sperm than nonsmokers. Morphologic abnormalities, particularly bicephalia, although prevalent among individual smokers, did not differ significantly (P greater than 0.9) when a comparison of smokers versus nonsmokers was made as a whole. Based on these observations and those of others demonstrating the presence of the mutagenic properties of smoke condensates, we suggest that decreases in sperm density and motility in cigarette smokers may be reflective of smoke condensate-induced mutagenic spermatogenital alterations.

A prospective study of drug use, smoking and contraceptives during early pregnancy

In a prospective study, 2436 women were interviewed regarding contraceptive technique used before pregnancy, on drug use, exposure to X-rays, smoking habits, and vaginal bleeding during the first 17 weeks of pregnancy. The study was conducted in Malmö during 1979 and early 1980. The study, compared with two similar Swedish studies made in 1963-65 in Malmö and a multicenter study from 1973-74, shows a drastic reduction of psychotropic drug use, from 13.5% to 3.0% and of hormone use from 3.75 to 1.1%. The use of analgetics, however, shows an increase, from 27% to 60.7%. For antibiotic and antihistamine use there is little or no difference. The study shows no connection between drug use and fetal malformation. Smoking habits have changed--the number of non-smokers is the same but the proportion of heavy smokers (more than 10 cigs/day) has decreased from 8.9% to 1.5%. 18 (0.8%) women become pregnant while using oral contraceptives and 13 (0.5%) with an IUD in place.

Effects of smoking on fetoplacental-maternal system during pregnancy

Fetoplacental function and maternal nutritional condition were assessed in order to clarify the mechanism of retarded fetal growth in pregnant women who smoked. Dehydroepiandrosterone sulfate (DHA-S) loading tests and measurements of cotinine, which is a major metabolite of nicotine, were also made. In heavy smokers, urinary estriol and serum levels of human placental lactogen (hPL) were lower than those in nonsmokers. There was no difference in maternal nutrition between smokers and nonsmokers. Heavy smokers demonstrated a lower conversion of DHA-S to estradiol than did nonsmokers. Levels of cotinine in maternal blood and umbilical cord blood of heavy smokers were remarkably higher than those in nonsmokers. Microscopic examination showed atrophic and hypovascular changes in placental villi from mothers who smoked. These results suggest that retarded fetal growth in heavy smokers is due to impairment of uteroplacental circulation as a result of the vasoconstricting effect of nicotine.

The effect of smoking during pregnancy on cord blood and maternal serum immunoglobulin levels

The effect of smoking on the fetal and maternal humoral immune parameters was evaluated in cord and maternal blood, collected at delivery from 163 mothers who smoked and 130 mothers who did not smoke, and their offspring. There was no difference in time of gestation between the two groups, but the mean birth weight of the offspring of mothers who smoked was decreased, as previously observed. There were higher levels of IgA (p less than 0.01), IgM (p less than 0.001), and IgG (p less than 0.001) in cord sera of children of mothers who smoked than in the offspring of mothers who did not smoke. Mothers themselves who smoked had higher levels of IgM (p less than 0.001) and IgG (p less than 0.001), but not IgA, as compared to control mothers who did not smoke. Since cord IgA and IgM are produced by the fetus, these results could be interpreted as being due to either a higher incidence of infection in utero or metabolic differences in the children of mothers who smoke. Either of these possibilities may explain the increased frequency of postpartum endometritis, increased incidence of fetal distress, and the characteristic of meconium-stained amniotic fluid in mothers who smoke.

Maternal smoking and prostacyclin production by cultured endothelial cells from umbilical arteries

A study was made of the production of prostacyclin (PGI2) by cultured endothelial cells from the umbilical veins of mothers who smoked and of matched mothers who did not smoke. Cells were obtained from 58 umbilical cords from 22 apparently healthy women, 11 mild smokers (less than 15 cigarettes per day), and 25 heavy smokers (more than 15 cigarettes per day). Production of PGI2 by the cells was calculated by measuring the amount of 6-keto-prostaglandin F1 alpha released in the culture medium after the addition of arachidonic acid, by means of a specific radioimmunoassay. Endotheliai cells from mild and heavy smokers were significantly less able to grow and to reach confluency than cells from nonsmokers. Smoking also resulted in a marked reduction in the capacity of cultured cells to produce PGI2. This was particularly apparent for the cells from heavy smokers. Smoking during pregnancy appears to induce some modifications in the enzymes of the prostacyclin pathway which persist in endothelial cells undergoing replication in primary culture even in the absence of the pathogenic factor.

Longitudinal study of the effects of maternal smoking on pulmonary function in children

We investigated the effects of maternal cigarette smoking on pulmonary function in a cohort of children and adolescents observed prospectively for seven years. A multivariate analysis revealed that after correction for previous forced expiratory volume in one second (FEV1), age, height, change in height, and cigarette smoking in the child, or adolescent, maternal cigarette smoking significantly lowered the expected average annual increase in FEV1 (P = 0.015). On the basis of this analysis, it is estimated that if two children have the same initial FEV1, age, height, increase in height, and personal cigarette-smoking history, but the mother of one has smoked throughout the child's life whereas the mother of the other has not, the difference in the change in FEV1 over time in the exposed child, as compared with that in the unexposed child, will be approximately 28, 51, and 101 ml after one, two, and five years, respectively, or a reduction of 10.7, 9.5, and 7.0 per cent, respectively, in the expected increase. These results suggest that passive exposure to maternal cigarette smoke may have important effects on the development of pulmonary function in children.