Higher Maternal BMI in Early Pregnancy Linked to Childhood Obesity Risk

Recent research presented at the European Congress on Obesity (ECO 2025) underscores the significant impact of maternal body mass index (BMI) during early pregnancy on the likelihood of children developing overweight or obesity. Conducted in Australia, the study reveals that a higher BMI in expectant mothers correlates with greater weights in their children from birth up to age ten, highlighting the necessity for supporting women and families with obesity prior to and during pregnancy.

The study, part of the LIMIT trial involving 2,121 pregnant women categorized as overweight or obese, examined the effects of maternal BMI on child growth metrics. Participants had an average age of 29.4 years and a median BMI of 31.1 at the start of their pregnancies. Half of the women received lifestyle intervention (LI) focused on dietary adjustments and increased physical activity, while the other half underwent standard antenatal care (SC).

According to researchers, women with overweight or obesity face heightened risks for various pregnancy complications, including gestational diabetes, hypertension, cesarean deliveries, and high infant birth weights--factors that can predispose their children to future obesity.

The initial findings from the LIMIT trial, published in 2014, indicated that infants of mothers in the LI group were 18% less likely to be born with a weight exceeding 4 kg (approximately 8 lbs 13 oz), a known indicator for childhood obesity. However, subsequent data showed no significant differences in other maternal or infant health outcomes between those who received lifestyle interventions and those who received standard care.

In this latest analysis, researchers tracked the children from birth through ages 10, focusing on several growth metrics. The results indicated a clear association between a mother's early pregnancy BMI and her child's growth trajectory. Specifically, for every increase of 5 kg/m² in maternal BMI, there was an associated increase of 0.11 kg/m² in the child's BMI at birth, escalating to 0.74 kg/m² by ages 8 to 10 years.

The influence of maternal BMI became increasingly pronounced as children aged, particularly between 3 to 5 years and again at ages 8 to 10. Notably, paternal BMI also played a role in affecting child weight and BMI, especially in the older age group.

Experts emphasize that addressing maternal health before and during pregnancy is crucial for reducing the risk of obesity in future generations. They stress that healthcare providers must prioritize strategies to support women in achieving optimal health and weight before conception to potentially break the cycle of intergenerational obesity.