Predictors of post-partum weight retention in a prospective longitudinal study

Post-partum weight retention (WR) occurs in 60-80% of women with some retaining 10kg with contributing factors reported as pre-pregnancy body mass index (BMI), gestational weight gain (GWG) and breastfeeding. A longitudinal study of pregnancy, with 12-month post-partum follow-up was conducted to determine factors associated with WR. Pregnant women (n=152) were recruited from the John Hunter Hospital antenatal clinic in New South Wales, Australia. Pre-pregnancy weight was self-reported; weight was measured four times during pregnancy (for GWG) and in the first 12 months post-partum. Infant feeding data were obtained via questionnaires. Breastfeeding was categorised as exclusive, predominant, complementary or not breastfeeding. Linear mixed models tested the predictors of WR, with and without adjustment for potential confounders. Compared with pre-pregnancy weight, 68% of women retained weight at 12 months, median (interquartile range) [4.5kg (2.1-8.9)]. After adjustment, GWG was positively associated with WR (P<0.01), but pre-pregnancy weight did not predict WR. For each additional week of any breastfeeding, 0.04kg less weight was retained. Compared with women who retained weight, those women who did retain had higher rates of exclusive breastfeeding at three months (P<0.05), but the number of weeks of exclusive breastfeeding failed to predict WR for all women. WR following childbirth is common and associated with GWG, while the number of weeks of any' breastfeeding contributed to post-partum weight loss. Whether these factors are modifiable strategies to optimise the weight status of women at this life stage requires further research.