Maternal "Junk Food" Diet During Pregnancy as a Predictor of High Birthweight: Findings from the Healthy Beginnings Trial

Background: A high infant birthweight is associated with future risk of a range of adverse health consequences. This study sought to determine whether maternal "junk food" diet (energy-dense, nutrient-poor) predicts high birthweight in first-time mothers in southwest Sydney, Australia. Methods: A community-based longitudinal study was conducted with a total of 368 first-time mothers and their newborns. Information about maternal "junk food" diet, including high consumption of soft drink, fast food, and/or processed meat and chips, and self-reported prepregnant weight and height of first-time mothers was collected by a face-to-face interview with mothers between 24 and 34 weeks of pregnancy. Birthweight was measured in hospital and reported by the mother, together with gestational age, when the baby was 6 months old. Logistic regression modeling was used to determine the factors predicting birthweight greater than 4.0 kg. Results: Eleven percent of newborns weighed more than 4.0 kg (12% boys, 9% girls). Compared with mothers who had a "junk food" diet, mothers who had not consumed "junk food" during pregnancy were significantly less likely to have a newborn weighing more than 4.0 kg, with adjusted odds ratio (AOR) 0.36, 95 percent confidence interval (CI) 0.14-0.91, p = 0.03, after adjusting for maternal weight status and gestational age. Compared with healthy and underweight mothers, overweight or obese mothers were more likely to have a newborn weighing more than 4.0 kg (AOR overweight 3.03, 95% CI 1.35-6.80; obese 3.79, 95% CI 1.41-10.25) after allowing for "junk food" diet and gestational age. Conclusions: Maternal "junk food" diet during pregnancy and prepregnant overweight and obesity were independent predictors of high infant birthweight. Early childhood obesity interventions should consider addressing these factors.