Interpregnancy weight changes and impact on pregnancy outcome in a cohort of women with a macrosomic first delivery: a prospective longitudinal study

OBJECTIVE To determine the median interpregnancy maternal weight change between first and second pregnancies, and second and third pregnancies and to assess the impact of this weight change on pregnancy outcome in a cohort of women with a macrosomic first delivery. STUDY DESIGN Prospective longitudinal study conducted over three pregnancies from 2007 to 2015. SETTING Tertiary referral maternity hospital, Dublin, Ireland. PARTICIPANTS Women were recruited if their first baby weighed >4.0 kg. METHODS The pregnancy outcomes in the second and third pregnancies were analysed separately. Data were also analysed for both interpregnancy intervals comparing outcomes for those who gained any weight, or more weight than the median, with those who did not. MAIN OUTCOME MEASURES Recurrent fetal macrosomia ≥4.0 kg and gestational diabetes mellitus. RESULTS There were 280 women who delivered a third baby between 2011 and 2015. There were no differences in pregnancy outcomes for the second pregnancy in women who gained interpregnancy weight compared with those who did not and those who gained more interpregnancy weight than the median compared with those who did not. There was a statistically significant increase in birth weight ≥4.0 kg (54.0% vs 39.6% p=0.03) in those women who gained any weight between the second and third pregnancies. In those women who gained more interpregnancy weight than the median (1.70 kg) between a second and third pregnancy, there was a significant increase in the rate of gestational diabetes (6.5% vs 1.4%, p=0.03). CONCLUSIONS This longitudinal study demonstrates that within this cohort maternal interpregnancy weight change between a second and third pregnancy is associated with an increase in birth weight ≥4.0 kg. Additionally, a gain of more weight than the median (1.70 kg) is associated with a higher rate of gestational diabetes.