Interpregnancy maternal weight change is not associated with offspring weight and obesity at age 2 years.

Background: Weight retention between pregnancies is associated with increased risk of perinatal complications, but it is unclear whether there is an association with offspring weight status. This study aimed to determine whether maternal interpregnancy weight change is associated with offspring overweight/obesity, controlling for confounding variables.

Subjects/methods: Routinely collected linked data from perinatal and child datasets, in Flanders, Belgium were used. Women having their first and second live births between 2009-2018 were included. The association between maternal interpregnancy weight change and overweight/obesity in the second child at 2 years was examined by logistical regression models.

Results: A total of 33,172 women were included. 52.7% (n = 17478) had a stable interpregnancy BMI, 24.1% (n = 8024) and 8.5% (n = 2821) had moderate and substantial BMI increases respectively. At 2 years, 91.6% (n = 30383) of the second offspring had a healthy weight, 0.6% (n = 210), 7.0% (n = 2312) and 0.8% (n = 267) were in the underweight, overweight and obesity BMI categories respectively. Multivariate analysis showed no statistical evidence that maternal interpregnancy BMI change is independently associated with overweight/obesity in the second child. The strongest independent factors were the first child (sibling) being in the obesity category at 2 years (odds ratio [OR] 7.2, [95% CI, 5.49-9.45] and being born Large for Gestational Age (LGA) (2.13 [1.92-2.37]). The following variables were also independently associated with the outcome measure: maternal African origin (1.90 [1.59-2.26]), maternal obesity at start of first pregnancy (1.33 [1.16-1.53]), excessive gestational weight gain in the second pregnancy (1.15 [1.04-1.28]), being born after a < 1-year interpregnancy time interval (1.17 [1.05-1.30]) and not being exclusively breastfed at 12 weeks old (1.29 [1.10-1.52]).

Conclusion: Sibling obesity and being born LGA were most strongly independently associated with overweight/obesity at 2 years. This supports the need for family interventions and to address risk factors for development of LGA infants. There was no independent association with interpregnancy weight gain, contrary to what was hypothesised.