The association between pre-pregnancy maternal BMI, self-reported alcohol intake and infant birth weight: A retrospective analysis of an Australian cohort.

Alcohol plays a major role in Australian culture with approximately 75% of females aged 18 years or over reporting having consumed alcohol in the previous year (2014–2015). The association between alcohol consumption and use in pregnancy with adverse health consequences for both mother and infant have been previously documented. The aim of this study was to investigate the dual impact of alcohol consumption and maternal body mass index (BMI) on infant birth weight. This was a retrospective cohort design using data from the Birthing Outcome System in southeast Australian hospital. A total of 14 487 births were included. Consumption of alcohol was self-reported and recorded categorically by staff as either yes or no. Within this cohort 715 (4.9%), 7268 (50.2%), 3658 (25.3%), 1558 (10.8%), 711 (4.9%) and 576 (3.9%) were underweight, of normal BMI, overweight, obese class I, II or III, respectively. In bivariate-adjusted models, women in the underweight BMI category, who consumed alcohol during pregnancy, were found to have a higher risk of delivering a low birth weight infant (adjusted odds ratio (AOR) 3.809, 95% confidence interval (CI): 1.175–12.349). Women who were classified as overweight, and consumed alcohol during pregnancy, experienced an increased risk of delivering an infant with macrosomia (AOR 1.551, 95% CI: 1.029–2.340). This analysis confirms that public health messages should still focus on encouraging women to abstain from drinking alcohol while pregnant, to minimise risk of adverse birth outcomes.