Factors associated with gestational weight gain in women with morbid obesity

Women with obesity are at increased risk of excessive gestational weight gain. Women with a body mass index (BMI) of 40 kg/m² or more are known to have different patterns of weight gain than women with lower levels of obesity. This study therefore aimed to determine the characteristics associated with gestational weight gain (GWG) among women with a BMI of 40 kg/m² or more.

Secondary analysis was undertaken on a retrospective cohort of women with a BMI of 40 kg/m² or more, with a singleton pregnancy referred to an antenatal healthy lifestyle service between 2009 and 2015 (n = 735). GWG was calculated by subtracting weight at the first antenatal appointment from final recorded weight in pregnancy provided the final weight was recorded from at least 34 + 0 weeks gestation. Univariable and multiple linear regression analyses were employed to determine the association between GWG and different maternal and infant characteristics.

Average GWG among women with a BMI of 40 kg/m² or more was 6.0 (±7.1)kg. Multiple regression showed GWG decreased with increasing BMI and increasing parity. Other socio-demographic factors were also significantly associated with GWG, with higher GWG seen among those with high levels of deprivation, where the highest household occupation was of a manual nature, in older women and women of non-White British ethnicity.

GWG in this cohort of women with a BMI of 40 kg/m² or more was within Institute of Medicine recommendations. Using a systems approach to GWG management that incorporates biological, psychological and socio-ecological factors is important.