Interpregnancy weight change as a potential risk factor for large-for-gestational-age infants: the Japan Environment and Children's Study.

OBJECTIVE: This study aimed to estimate the impact of interpregnancy weight change from the first to the second pregnancy on the risk of infants being large for gestational age (LGA).

METHODS: This nationwide prospective birth cohort analysis included 3245 women who delivered their first two live singletons between 2011 and 2014. Interpregnancy weight change was calculated as the difference between the prepregnancy body mass index (BMI) of the first and second pregnancies. LGA infants were compared among three interpregnancy weight change groups: weight loss (a BMI loss >1 unit), weight gain (a BMI gain >1 unit), and stable weight (BMI maintained within - 1 to <1 unit). Interpregnancy weight change was assessed in mothers with a BMI <25 and ≥25 kg/m2 , and adjusted odds ratios (ORs) were calculated for LGA infants by multiple logistic regression.

RESULTS: The incidence of LGA infants was 8.6% (279 out of 3245). Compared with the stable weight group, interpregnancy weight gain was associated with an increased risk of infants being LGA (adjusted OR: 1.69, 95% confidence interval: 1.21-2.36) in the normal BMI (<25 kg/m2 ) group. In contrast, in the overweight/obese BMI (≥25 kg/m2 ) group, interpregnancy BMI was not a significant risk factor for LGA infants.

CONCLUSIONS: Accurate risk stratification using interpregnancy BMI could assist the clinical management of women with a normal BMI who are at risk of delivering LGA infants.