New research presented at the European Congress on Obesity (ECO 2025) reveals that the weight of both mothers and fathers significantly influences their child’s growth and risk of obesity.
The Australian study, part of the ongoing LIMIT trial, found that the higher a woman’s body mass index (BMI) during pregnancy, the heavier her child tends to be from birth up to the age of ten. Interestingly, the father’s BMI also plays a notable role in the child’s weight by age ten, highlighting the importance of both parents’ health before conception.
The LIMIT trial involved 2,121 pregnant women with overweight or obesity, with an average age of 29.4 years and a median BMI of 31.1 during early pregnancy. These women were split into two groups. Half of them participated in a lifestyle intervention (LI) that focused on healthy eating habits and regular physical activity.
They received guidance on increasing their intake of fruits and fiber, while cutting back on refined carbohydrates and saturated fats. The other half received standard antenatal care (SC) without additional dietary or lifestyle support.
The primary goal of the trial was to determine if lifestyle changes during pregnancy could lower the risks associated with maternal obesity, such as gestational diabetes, high blood pressure, cesarean deliveries, and high birth weights, which are linked to childhood obesity.
Professor Jodie Dodd from the University of Adelaide, who led the research, explained that around 50% of women enter pregnancy with overweight or obesity, putting both themselves and their babies at risk for health complications. The study aimed to see if changes in diet and physical activity during pregnancy could reduce these risks.
The initial findings, published back in 2014, showed some promise. Infants born to women in the lifestyle intervention group were 18% less likely to weigh over 4 kg (8 lb 13 oz) at birth, a risk factor for childhood obesity.
However, there were no other significant differences between the two groups in terms of pregnancy complications or long-term health outcomes for the mothers and their children. As the children grew, researchers continued to monitor their health and growth, but they found no substantial differences between the two groups in overall health or development.
For the latest phase of the study, Professor Dodd and her team focused specifically on how the mother’s BMI during early pregnancy affected the child’s growth patterns. They analyzed data from birth through various stages: 6 months, 18 months, 3–5 years, and 8–10 years of age.
The results were clear: a child’s growth was closely linked to the mother’s BMI at the start of pregnancy. For every 5 kg/m² increase in the mother’s BMI, the child’s BMI rose by 0.11 kg/m² at birth and grew to 0.74 kg/m² by the time the child reached 8–10 years of age.
This effect became even more pronounced as the child got older, especially noticeable from ages 3–5 and strongest at ages 8–10.
The study also uncovered that the father’s BMI had a significant impact on the child’s weight and BMI by the time they were 8–10 years old. This suggests that both parents’ health and lifestyle choices are important factors in a child’s risk of obesity.
Professor Dodd emphasized that while lifestyle interventions during pregnancy have not shown major improvements in health outcomes, the parents’ health before pregnancy plays a critical role. “We know that women living with overweight or obesity are at increased risk of complications like high blood pressure in pregnancy,” she said.
“But what we found here is that a woman’s BMI in early pregnancy impacts how her child grows from birth to 8–10 years of age. 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.”
The findings highlight the importance of supporting women—and their families—in achieving a healthy weight before pregnancy.
According to Professor Dodd, focusing on health and weight optimization before conception could help break the cycle of obesity that passes from one generation to the next. This approach may help prevent the long-term health consequences of obesity for both mothers and their children.
These results call for a shift in how health care providers address maternal health, placing more emphasis on pre-pregnancy health rather than waiting until pregnancy begins. Supporting both mothers and fathers in achieving healthy weight and lifestyle habits could be a key strategy in reducing childhood obesity rates and improving long-term health outcomes for families.
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