The greater a woman’s BMI in early pregnancy, the more likely her child is to develop overweight or obesity, study finds

New research being presented at the European Congress on Obesity (ECO 2025) highlights the need to support women and their families with overweight or obesity to optimize their health and weight before they become pregnant.

The Australian study found the greater a woman’s BMI in pregnancy, the greater her child’s weight from birth to the age of ten. This was the case regardless of whether the woman took part in a dietary and lifestyle intervention (LI) while pregnant or received standard antenatal care (SC). They also reported that the BMI of the father significantly influences the child’s weight at age 10.

The results are the latest from the LIMIT trial which involved 2,121 pregnant women with overweight or obesity (average age 29.4 years, median BMI 31.1 in early pregnancy).

Half of the women took part in the LI, which consisted of advice and support for eating a healthy diet (for example, eating more fruit and fiber and reducing intake of refined carbohydrates and saturated fat) and increasing physical activity. The other participants received standard antenatal care (standard care group, SC).

“Women with overweight or obesity are at increased risk of pregnancy complications, like gestational diabetes, high blood pressure, cesarean birth and high infant birth weight, and for their children to develop obesity,” says researcher Professor Jodie Dodd, of the University of Adelaide, South Australia, Australia.

“With approximately 50% of women entering pregnancy with overweight or obesity, the trial was carried out to see if changes in diet and physical activity during pregnancy could reduce these risks.”

The initial results, which were published in 2014, showed that infants whose mothers took part in the LI group were 18% less likely to have a birth weight above 4kg (8lb 13oz), a known risk for childhood obesity. However, there were no other differences in maternal or birth outcomes, including pregnancy complications, between the two groups.

The children were also followed-up throughout childhood. There was no evidence of a difference in health or growth of the children from women in either the LI and SC group.

For the latest study, Professor Dodd and colleagues examined the effect of maternal BMI in early pregnancy on childhood weight and other measures of growth taken at birth and aged 6 months, 18 months, 3–5 years old and 8–10 years old.

They found that a child’s growth was linked to its mother’s BMI in early pregnancy—and that every 5kg/m² increase in a woman’s BMI was associated with an increase in their child’s BMI by 0.11kg/m² at birth, to 0.74kg/m² at 8–10 years of age.

The effect of maternal BMI became more prominent at age 3–5 years and was particularly noticeable at 8–10 years. This was the case across the different measures of child growth studied—BMI, weight and their standardized measures. Additionally, paternal BMI impacted child weight and BMI, particularly at ages 8–10 years.

Professor Dodd says, “We know that women living with overweight or obesity are at increased risk of complications like high blood pressure in pregnancy. We also know that lifestyle interventions during pregnancy are ineffective for improving health outcomes for women and their baby/child.

“What we found here was that a woman’s BMI in early pregnancy impacts how her child grows from birth to 8–10 years of age, so, if a woman’s BMI is higher going into pregnancy, her child’s risk of overweight and obesity increases too. Fathers also have a role to play, as paternal BMI also contributes to child obesity.

“It’s vital that health care providers focus on supporting women and their families to optimize their health and weight before pregnancy, if we are to intervene and potentially reduce the intergenerational cycle of obesity.”

Provided by
European Association for the Study of Obesity