Women with the highest levels of obesity are known to have different patterns of weight gain during pregnancy than other women. This study looked at what factors were linked to pregnancy weight gain in women with the highest levels of obesity. Pregnancy weight gain was calculated by subtracting the woman’s weight at her first pregnancy appointment from her weight at the end of pregnancy, providing she was at least 34 weeks pregnant when she was weighed.
The higher the woman’s body mass index above 40 kg/m2 at the start of pregnancy, the less weight they gained in pregnancy. Women gained less weight during pregnancy if they already had one or more children rather than were having their first baby or if they lived in households where no one worked. Weight gain was also linked to whether the woman lived in a deprived area and weight gain was higher in women from an ethnic minority. In the future any interventions during pregnancy to help women gain the correct amount of weight need to consider multiple things including how many children they already have, as well as the influence of the woman’s family and friends and where the woman lives.