Alcohol consumption and cigarette smoking by Australian women: changes with pregnancy and lactation

The consumption of alcohol and smoking of cigarettes are both common practices in Australian society. With continued public health efforts exposure to both alcohol and nicotine during pregnancy has diminished, however little is known about exposure to these toxins in the postnatal period and the effect on the breastfed infant. To investigate the pattern of alcohol consumption and cigarette smoking in the postnatal period and the effect on breastfeeding outcomes, a longitudinal study was conducted in two public hospitals with maternity wards in Perth, Australia. Data for the Perth Infant Feeding Study (PIFSII) were collected from 587 mothers between mid-September 2002 and mid-July 2003. While in hospital participating mothers completed a self-administered baseline questionnaire. Follow-up telephone interviews were conducted at 4, 10, 16, 22, 32, 40 and 52 weeks. Data collected included sociodemographic, biomedical, hospital related and psychosocial factors. Further analysis of alcohol data was undertaken on the 1995 and 2001 National Health Survey (NHS) data sets to provide a national perspective. Alcohol and smoking related data were analysed and described using frequency distributions, means and medians. Univariate logistic regression was used to screen for potentially significant variables for subsequent incorporation in the multivariate analysis. Multivariate logistic regression analysis was employed to determine the effect of alcohol consumption and cigarette smoking on breastfeeding outcomes prenatally, antenatally and postnatally, after adjusting for factors identified in the literature as being associated with breastfeeding initiation and duration. The relationship between smoking status and breastfeeding duration was determined using survival analysis.Analysis of the relationship between breastfeeding duration and the level of postpartum intake was investigated using a Cox hazards model with repeated measures for alcohol consumption. Results showed that: 1. PIFSII. During pregnancy approximately 32% of women stopped drinking alcohol. Thirty five percent of pregnant women continued to consume alcohol during their pregnancy with 82.2% of these women consuming two or fewer standard drinks per week. At 4, 6 and 12 months postpartum, 46.7%, 47.4% and 42.3% of breastfeeding women were consuming alcohol, respectively. 2. NHS. Sixteen point four percent and 1.3% of pregnant women from the 1995 and 2001 NHS, respectively were consuming more than that recommended in ‘Guideline 11’ from the National Health and Medical Research Council of Australia (ie >7 standard drinks/week). 3. NHS. Thirteen percent of lactating mothers from the 1995 NHS and 16.8% from the 2001 NHS were consuming seven or more standard drinks of alcohol in the reference week, thus exceeding the NHMRC recommended level. 4. PIFSII. After 6 months of follow up, women who consumed alcohol at levels of more than two standard drinks per day were almost twice as likely to discontinue breastfeeding earlier than women who drank below these levels (HR 1.9, 95% CI 1.1, 3.0). 5. PIFSII. With regard to smoking, 226 (39%) of mothers reported smoking pre- pregnancy. Mothers who smoked were more likely to have a partner who smoked, to have consumed alcohol prior to pregnancy and less likely to attend antenatal classes.They were also less likely to know how they were going to feed their baby before conception and be more inclined to consider stopping breastfeeding before four months postpartum. 6. PIFSII. Women who smoked during pregnancy had a lower prevalence and shorter duration of breastfeeding than non-smoking mothers (28 weeks versus 11 weeks, 95% CI: 8.3-13.7). This effect remained even after adjustment for age, education, income, father’s smoking status, mother’s country of birth, intended duration of breastfeeding >6 months and birth weight (risk ratio HR 1.59, 95% CI 1.22 to 2.08). 7. PIFSII. Two hundred and twenty six (39%) mothers reported smoking prior to pregnancy and 77 (34%) of these stopped smoking during pregnancy. Quitting smoking during pregnancy was significantly associated with breastfeeding for longer than six months (OR = 3.70, 95% CI 1.55 to 8.83; p