Postpartum weight trajectories in overweight and lean women

Backgroundoverweight and obesity in women of reproductive age are increasing and are often linked with excessive weight gain in pregnancy and weight retention after birth. Studies on spontaneous maternal weight trajectory after childbirth are scarce.Objectivewe describe women's spontaneous weight trajectory during the first six weeks of the postpartum period and its relationship between Body Mass Index and socio-demographical, behavioural and psychological variables.Designdata from 212 women who gave birth in three regional hospitals were collected prospectively between December 2015 and February 2016. Potential determinants were examined during pregnancy and the postpartum period at four and six weeks after childbirth. Descriptive statistics and a linear multivariate regression model were used. Early postnatal weight retention (PWR) was defined as the difference between the maternal weight six weeks after childbirth and the pre-pregnancy weight (kg).Measurements and findingsmean PWR at six weeks after childbirth was 3.3 kg (SD 4.1), with a range between −7 and +16.2 kg; 81% reported some weight retention (PWR>0 kg), and 36% showed a high weight retention (PWR≥5 kg). Women with a BMI <25 kg/m2 showed a significantly higher mean PWR six weeks after childbirth compared to women with a BMI ≥25 kg/m2 (4.0 kg versus 1.6 kg, p=0.002). There was a significant correlation between maternal weight retention and gestational weight gain (GWG) (B=0.65, p<0.001) and pre-pregnancy body mass index <25 kg/m2 (B=1.12, p=0.017), six weeks after childbirth.Key conclusionsweight retention six weeks after childbirth is associated with pre-pregnancy BMI and GWG, but contrary to expectations, lean women with excessive GWG tended to retain most weight after childbirth. No significant associations with several socio-demographical, behavioural and psychological variables were found.Implications for practiceweight management strategies around pregnancy should not be limited to overweight and obese mothers. Women with pre-pregnancy BMI <25 kg/m2 require equal attention to prevent postnatal weight retention.