Maternal smoking, weight status and dietary behaviours during pregnancy: Findings from first-time mothers in south-west Sydney, Australia

Background: Few studies have been conducted examining the relationship between maternal smoking, weight status and dietary behaviours during pregnancy. Aim: The objective of the study was to examine the relationship between maternal smoking, weight status and dietary behaviours during pregnancy. Methods: An analysis of cross-sectional baseline survey data was conducted with 406 first-time mothers participating in the Healthy Beginnings Trial (HBT) conducted in south-west Sydney, Australia. Mothers' reports of their smoking status, dietary behaviours and pre-pregnancy weight and height were collected through face-to-face interviews. The relationships were examined using log-binomial regression modelling. Results: Maternal smoking status was not associated with weight status. However, smoking was positively associated with soft drink consumption and negatively associated with daily fruit intake. After adjusting for age, marital status and education level, mothers who reported consuming >1 cup of soft drink per day were more likely to smoke than those consuming less soft drink (adjusted risk ratio, ARR 1.48, 95% CI 1.02-2.22, P = 0.05). Mothers who reported having ≥2 serves of fruit daily were significantly less likely to smoke than those having less fruit (ARR 0.54, 95% CI 0.29-0.95, P = 0.04). Conclusions: The study found no evidence linking maternal smoking and weight status and did not support the notion that smoking could lead to a lower weight status. However, maternal smoking was associated with fruit and soft drink consumption and needs to be considered while examining dietary behaviours and weight status.