Maternal water consumption during pregnancy and congenital cardiac anomalies

This case-control study, conducted in a California county that had a local incident of water contamination in 1981, investigated the relation between a mother's reported consumption of tap water during pregnancy and congenital cardiac anomalies in their offspring born during 1981-1983. Data were obtained from telephone interviews with 145 mothers of children born with a severe cardiac anomaly and 176 mothers of children born without such an anomaly. A positive association between a mother's consumption of home tap water during the first trimester of pregnancy and cardiac anomalies in her infant was unrelated to the incident of water contamination, the mother's race, or her educational level. A negative relation was found between a mother's use of bottled water and cardiac anomalies among the infants. These findings corresponded primarily to births in 1981. These data could not fully distinguish between a potential causal agent in the water and differential reporting of exposure by study subjects.     

Maternal cigarette smoking and the risk of tubal pregnancy.

The association between maternal smoking and the occurrence of tubal pregnancy was evaluated in a population-based case-control study of members of the Group Health Cooperative of Puget Sound, Seattle, Washington. Women hospitalized with tubal pregnancy from October 1981 through September 1986 (n = 274) were compared with reproductive-age women who were at risk of becoming pregnant during the same time period (n = 727). The relative risk of tubal pregnancy associated with ever having smoked cigarettes was 1.3 (95% confidence interval (CI) 1.0-1.8). Compared with women who had never smoked, those who smoked at the time of conception had a 40% increase in the risk of tubal pregnancy (95% CI 1.0-2.0). These results support earlier epidemiologic and nonepidemiologic reports of a greater risk of tubal pregnancy associated with current or recent maternal cigarette smoking.     

Maternal smoking during pregnancy and smoking by adolescent daughters.

OBJECTIVES. Since cigarette smoking in adolescence represents a crucial entry point in the progression to illicit drugs, risk factors for adolescent smoking have public health implications. The influence of mothers on children's smoking appears to be greater than that of fathers. To explain the selective influence of mothers, we examined the consequences of maternal smoking during pregnancy in two longitudinal samples. METHODS. Analyses were conducted on follow-up interview data from two dyadic samples of mothers and firstborn adolescents for whom data on maternal smoking during and after pregnancy were available (192 mother-child pairs originating from New York State and 797 dyads from a national sample). RESULTS. In both samples, maternal smoking during pregnancy, when postnatal smoking was controlled, selectively increased the probability that female children would smoke and would persist in smoking (adjusted odds ratios of about 4). CONCLUSIONS. The findings suggest that nicotine or other substances released by maternal smoking can affect the fetus, perhaps through the nicotinic input to the dopaminergic motivational system, so as to predispose the brain in a critical period of its development to the subsequent addictive influence of nicotine consumed more than a decade later in life.     

Maternal cigarette smoking during pregnancy and risk of oral clefts in newborns.

The results of previous epidemiologic research on the possible association between maternal smoking during pregnancy and risk of oral clefts in offspring have been inconsistent. This may be due in part to methodological limitations, including imprecise measurement of tobacco use, failure to consider etiologic heterogeneity among types of oral clefts, and confounding. This analysis, based on a large case-control study, further evaluated the effect of first trimester maternal smoking on oral facial cleft risk by examining the dose-response relationship according to specific cleft type and according to whether or not additional malformations were present. A number of factors, including dietary and supplemental folate intake and family history of clefts, were evaluated as potential confounders and effect modifiers. Data on 3,774 mothers interviewed between 1976 and 1992 by the Slone Epidemiology Unit Birth Defects Study were used. Study subjects were actively ascertained from sites in areas around Boston, Massachusetts and Philadelphia, Pennsylvania; the state of Iowa; and southeastern Ontario, Canada. Cases were infants with isolated defects--cleft lip alone (n = 334), cleft lip and palate (n = 494), or cleft palate alone (n = 244)--and infants with clefts plus (+) additional malformations: cleft lip+ (n = 58), cleft lip and palate+ (n = 140), or cleft palate+ (n = 209). Controls were infants with defects other than clefts, excluding defects possibly associated with maternal cigarette use. There were no associations with maternal smoking for any oral cleft group, except for a positive dose response among infants with cleft lip and palate+ (for light smokers, odds ratio (OR) = 1.09 (95% confidence interval (CI): 0.6, 1.9); for moderate smokers, OR = 1.84 (95% CI: 1.2, 2.9); and for heavy smokers, OR = 1.85 (95% CI: 1.0, 3.5), relative to nonsmokers). This finding may be related to the additional malformations rather than to the cleft itself.     

Exposure to misoprostol and hormones during pregnancy and risk of congenital anomalies

This study evaluated the association between use of misoprostol and other drugs to induce menstruation, and congenital anomalies. A sample of 4,856 pregnant women 20 years and older were enrolled consecutively in prenatal services in the Unified National Health System, in six Brazilian State capitals. Data on socio-demographics and use of medicines were obtained using an interview from the 21st to 28th week of pregnancy. Other data, including information on delivery and diagnosis of congenital anomalies by the attending neonatal physician were obtained from patient charts. Potential confounders were adjusted by logistic regression. Use of drugs to induce menstruation was reported by 707 women (14.6%), of whom 120 (17%) reported use of misoprostol. After adjusting for the study center, a positive association was observed between misoprostol and congenital anomalies (OR = 2.64; 95% CI: 1.03-6.75); a positive association was also observed for sex hormones (OR = 2.24; 95% CI: 1.06-4.74). The results suggest that the use of misoprostol or sex hormones during pregnancy increases the risk of congenital anomalies.     

Maternal smoking during pregnancy and offspring IQ

BACKGROUND: Maternal smoking in pregnancy lowers birthweight. It is unclear, however, whether smoking during pregnancy lowers offspring IQ, and, if it does, whether it is through the smoking effect on fetal growth. METHOD: Representative samples of low birthweight (<2500 g) and normal birthweight children born in 1983-85 from inner-city and suburban communities in southeast Michigan, USA were assessed at ages 6, 11, and 17, using Wechsler intelligence tests. Smoking during pregnancy was ascertained from mothers at the first assessment; and smoking at any time was ascertained at the first and second assessment. Generalized estimating equation models were used, with children's IQ at all three assessments as outcomes (n = 798). RESULTS: Without adjustment, offspring of mothers who smoked during pregnancy scored 6.8 IQ points lower than offspring of mothers who never smoked, on average. Low birthweight children scored 5.4 IQ points lower than normal birthweight children, on average. The statistical association of maternal smoking with offspring IQ was confounded by maternal characteristics, chiefly, maternal cognitive ability as measured by IQ and education; adjustment for these factors eliminated the association. By contrast, adjustment for maternal IQ and education as well as smoking during pregnancy had a negligible effect on the low birthweight-related IQ deficit. Low birthweight did not mediate the association of smoking and lowered IQ in offspring. CONCLUSION: Maternal smoking during pregnancy is a proxy for a matrix of vulnerabilities for adverse child cognitive development and has no direct causal effect on child's IQ. The relationship of low birthweight and IQ is independent of maternal smoking and maternal cognitive abilities.     

Maternal smoking during pregnancy and childhood obesity

A recent cohort study suggested that maternal smoking during pregnancy might be a risk factor for childhood obesity. Data from the obligatory school entry health examination in six Bavarian (Germany) public health offices in 1999-2000 were used to assess the relation between maternal smoking during pregnancy and childhood obesity (n = 6,483 German children aged 5.00-6.99 years). A body mass index greater than the 90th percentile was defined as overweight, and a body mass index greater than the 97th percentile was defined as obesity. The main exposure was maternal smoking during pregnancy. The prevalences of overweight and obesity, expressed as percentages, increased in the following order: never smoked (overweight: 8.1, 95% confidence interval (CI): 7.2, 9.0; obesity: 2.2, 95% CI: 1.7, 2.7); less than 10 cigarettes daily (overweight: 14.1, 95% CI: 11.1, 17.7; obesity: 5.7, 95% CI: 3.7, 8.2); and 10 or more cigarettes daily (overweight: 17.0, 95% CI: 10.1, 26.2; obesity: 8.5, 95% CI: 3.7, 16.1). The adjusted odds ratios for maternal smoking during pregnancy were 1.43 (95% CI: 1.07, 1.90) for overweight and 2.06 (95% CI: 1.31, 3.23) for obesity. A dose-dependent association between overweight/obesity and maternal smoking during pregnancy was observed that could not be explained by a wide range of confounders, suggesting that intrauterine exposure to inhaled smoke products rather than lifestyle factors associated with maternal smoking accounts for this finding.     

Maternal smoking during pregnancy: no association with congenital malformations in Missouri 1980-83.

Using a multisource birth defects registry developed by the Missouri Center for Health Statistics for the years 1980-83, we examined the relation between maternal smoking during pregnancy and the occurrence of congenital malformations. There were 288,067 live singleton births in this data set of which 10,223 had one or more congenital malformations. When adjusted for potential confounders the odds ratio for congenital malformations in the infants of women who smoked during pregnancy was not increased (odds ratio = 0.98, 95% confidence interval = 0.94 - 1.03). We examined the relation between smoking and groups of malformations using the International Classification of Diseases, 9th Revision, as well as analyzing for certain specific malformations within each group and found no increased risk for infants of smokers.     

Maternal exposure to ambient air pollutants and risk of congenital anomalies

Studies have suggested an association between maternal exposure to ambient air pollution and risk of congenital anomaly. The aim of this study is to investigate the association between exposure to black smoke (BS; particulate matter with aerodynamic diameter <4 μg/m³) and sulphur dioxide (SO₂) during the first trimester of pregnancy and risk of congenital anomalies. We used a case-control study design among deliveries to mothers resident in the UK Northern health region during 1985-1990. Case data were ascertained from the population-based Northern Congenital Abnormality Survey and control data from national data on all births. Data on BS and SO₂ from ambient air monitoring stations were used to average the total pollutant exposure during the first trimester of pregnancy over the daily readings from all monitors within 10 km of the mother's residence. Logistic regression models estimated the association via odds ratios. A significant but weak positive association was found between nervous system anomalies and BS (OR=1.10 per increase of 1000 μg/m³ total BS; 95% CI: 1.03, 1.18), but not with other anomaly subtypes. For SO₂, a significant negative association was found with congenital heart disease combined and patent ductus arteriosus: OR significantly <1 for all quartiles relative to the first quartile. The relationship between SO₂ levels and other anomaly subtypes was less clear cut: there were either no significant associations or a suggestion of a U-shaped relationship (OR significantly <1 for moderate compared to lowest levels, but not with high SO₂ levels). Overall, maternal exposure to BS and SO₂ in the Northern region had limited impact on congenital anomaly risk. Studies with detailed exposure assessment are needed to further investigate this relationship.     

Maternal smoking during pregnancy and limb reduction malformations in Sweden.

OBJECTIVE: This study was undertaken to investigate a possible connection between different types of limb reduction defects and maternal smoking during pregnancy. METHODS: With the use of the Swedish health registries, 610 cases of limb reduction malformations were selected from among 1 109 299 infants born between 1983 and 1993 with known smoking exposure in early pregnancy. Confounders such as maternal age and parity were controlled for with the use of the Mantel-Haenszel technique. RESULTS: The odds ratio for any maternal smoking among all cases of limb reductions was 1.26 (95% confidence interval = 1.06, 1.50). The main subgroups of limb reduction defects showed similar odds ratios, but in longitudinal reduction defect, only unilateral cases showed an association with maternal smoking. CONCLUSIONS: This study supports an association between maternal smoking and limb reduction malformations, but further work is needed before a causal inference can be made.     

Maternal smoking and the risk of polyhydramnios.

BACKGROUND. Washington State birth certificates were used to conduct a population-based case-control study to assess the possible association of maternal smoking with polyhydramnios. METHODS. All singleton births complicated by polyhydramnios (n = 557) were identified from the vital records for the years 1984 to 1987. For comparison, 1671 records were randomly selected for the same years from singleton births uncomplicated by polyhydramnios. RESULTS. Women who reportedly smoked prenatally were found to be at increased risk for polyhydramnios (relative risk [RR] = 1.7, 95% confidence interval [CI] = 1.5-2.1, adjusted for marital status, maternal age, and parity). When women with conditions known to be associated with polyhydramnios were excluded, the risk for those who smoked prenatally remained elevated (RR = 1.8, 95% CI = 1.1-2.3). CONCLUSION. Overdistention of the uterus from polyhydramnios may cause a variety of pregnancy complications. The observed association of smoking with polyhydramnios may be a further indication for public health interventions aimed at preventing smoking during pregnancy.     

Maternal occupational exposure during pregnancy and the risk of spina bifida.

OBJECTIVES: A case-control study was carried out to explore associations between spina bifida and occupational exposure of the mother. METHODS: The cases were children with spina bifida aperta born between 1980 and 1992 from nine hospitals in the Netherlands. The controls were children born healthy in the same period as the cases, from hospitals and from the general population. Data collection was carried out in two steps. Firstly, postal questionnaires were sent to all the parents of cases and controls to gather information on occupations and potential confounders. In the second phase of the study, information on specific exposures was collected by means of job and task specific personal interviews. Interviews were performed with 55 case mothers and 66 control mothers who had occupations with a potential for chemical or physical exposure. Those exposures were assumed to be negligible for--for example, teachers and secretaries, so personal interviews were not indicated for these women. Information was collected on specific tasks in the period just after conception, and on the associated use of chemical or physical agents, frequency of exposure, and use of protective equipment. RESULTS: The analyses of occupation showed an increased risk for women working in agricultural occupations (OR = 3.4, CI:1.3-9.0), and, although less distinct, for cleaning women (OR = 1.7, CI:0.9-3.4). Only a few women seemed to be occupationally exposed to chemical or physical agents. No differences in occurrence of specific exposures could be detected between cases and controls. Besides, no differences were seen in pesticide or disinfectant exposure among case and control mothers in agricultural occupations. CONCLUSIONS: Occupational exposures of the mother during pregnancy were infrequent and did not seem to play an important part in the aetiology of spina bifida in this study. The association found between spina bifida and maternal agricultural occupations could not be explained by the use of pesticides by the mother or by any other occupational exposure.     

Maternal smoking, alcohol, and coffee use during pregnancy and son's risk of testicular cancer

It has been suggested that increased risk for testicular cancer occurring worldwide may be due to exposures during fetal development. Lifestyle or environmental exposures may be the most important predictors of risk. However, few studies have directly examined these exposures prospectively. The Child Health and Development Studies is a 40-year follow-up of 20,530 pregnancies occurring between 1959 and 1967. There were 20 cases of testicular cancer diagnosed through 2003 among sons with a maternal interview in early pregnancy. Cases were matched to three controls on birth year and race. Odds ratios and 95% confidence intervals were calculated with exact conditional logistic regression. Compared to controls, mothers of testicular cancer cases were more likely to drink alcohol (unadjusted odds ratio, 3.2; 95% confidence interval, 0.83-15.48 for above vs. below the median for controls) and less likely to drink coffee (unadjusted odds ratio, 0.19; 95% confidence interval, 0.02-1.02 for above vs. below the median). Case mothers were neither more nor less likely to smoke. Although low power may limit interpretation of negative results, the prospective design minimizes bias. In this cohort, maternal serum testosterone in pregnancy was previously reported to be lower in women who drank alcohol. Because populations with high testicular cancer risk also have lower maternal testosterone, we suggest that testosterone could play a role in explaining the higher risk of son's testicular cancer among mothers who drank alcohol during pregnancy.     

Maternal smoking and the risk of congenital birth defects: a cohort study

BACKGROUND: The literature linking gestational smoking to congenital defects has been very inconsistent. The purpose of this study was to reinvestigate the relation between gestational smoking and congenital malformations. METHODS: This study was a retrospective cohort (N = 18,016) of live births in the TriHealth Hospital system from 1 January 1998 to 31 December 1999. The cohort included 1,943 mothers who were smokers. Congenital defects were grouped into 22 different categories. Multifactorial logistic regression was used to find any association between exposure and the possible outcomes. RESULTS: Mothers who smoked were significantly younger and had babies of lower birth weight and shorter gestational age (P < .05). Of the 22 categories of congenital defects, only cardiovascular system abnormalities showed a significant difference (P < .01) between the two groups. The remaining 21 categories of congenital defects showed no statistical difference. CONCLUSION: Women who smoke during pregnancy have infants that are significantly smaller and of shorter gestational age compared with mothers who do not smoke. Based on these data and findings from most of the available literature, however, gestational smoking is unlikely to cause a large increase in congenital birth defects.     

Maternal smoking and congenital heart defects

The Swedish Child Cardiology Registry (CCR) and the Swedish Medical Birth Registry (MBR) were used to investigate a possible association between maternal smoking during pregnancy and congenital heart defects. Among 1,413,811 infants born in 1983–1996 with known smoking exposure in early pregnancy, 3384 infants with congenital heart defects were selected (458 term infants with persistent ductus arteriosus (PDA) identified from MBR or CCR, and 2926 infants with other heart defects, identified from CCR). After controlling for year of birth, maternal age, parity, and educational level, a weak, statistically significant association between all heart defects and maternal smoking was found (odds ratio (OR): 1.09; 95% confidence interval (CI): 1.01–1.19). When infants with isolated PDA were removed from the case group the significance disappeared (OR: 1.07; 95% CI: 0.98–1.17). For truncus abnormalities (OR: 1.23; 95% CI: 1.02–1.49), atrial septal defects (OR: 1.63; 95% CI: 1.04–2.57), and PDA (OR: 1.30; 95% CI: 1.05–1.62), a rather strong effect of maternal smoking was indicated. The increased OR for PDA remained when gestational duration and intrauterine growth was also controlled for. Further research based on independent data sets is needed to conclude whether the risk estimates for maternal smoking are true and truly differ between the groups. The classification system used (with 24 classes) is described in enough detail to permit a repetition of the study.