Researchers have found that higher maternal pre-/early-pregnancy BMI is not a key driver of higher adiposity in the next generation, suggesting that lifestyle is more likely to affect their child’s BMI than their own weight

Кирилл Рыжов baby child weight measure obese overweight

Researchers from Imperial College London and the University of Bristol have found that lifestyle is more likely to affect a child’s body mass index (BMI) than the weight of their mother before and during pregnancy. A mother’s high BMI before and during pregnancy is not a major cause of high BMI in their offspring, they found, indicating that childhood and teen obesity is more likely to be a result of lifestyle factors.

According to UK Government figures, 9.9% of reception-age children (age 4–5 years) are obese, with a further 13.1% overweight. At age 10–11 (Year 6), 21.0% are obese and 14.1% overweight.

Nature or nurture

Higher maternal BMI before or during pregnancy is known to be associated with higher BMI throughout childhood, but the question of whether it is the mother’s weight before or during pregnancy that contributes to childhood obesity or other lifestyle and environmental factors remains unclear.

To investigate this question, researchers from the University of Bristol and Imperial College London used data from the “Children of the 90s” (also known as the Avon Longitudinal Study of Parents and Children), and data from the “Born in Bradford” longitudinal study.

For their study, published in the journal BMC Medicine, researchers used polygenic risk scores and Mendelian randomisation, measuring variation in genes to determine the effect of an exposure on an outcome, to investigate whether associations between mothers’ BMIs and their children’s from birth to adolescence are causal.

They looked at birthweight and BMI at age 1 and 4 years in both “Children of the 90s” and “Born in Bradford” participants, as well as BMI at age 10 and 15 years in just the “Children of the 90s” participants.

Since the effects being explored may differ by ethnicity, the authors reported that they limited analyses to two ethnic groups: White European and South Asian.

Interventions targeting everyone needed

The researchers found that there was a moderate causal effect between maternal BMI and the birthweight of children, however they said they ‘found no strong evidence for a causal effect of maternal BMI on offspring adiposity beyond birth’.

Lead author Dr Tom Bond, Senior Research Associate at the University of Bristol, explained: ‘We found that if women are heavier at the start of pregnancy this isn’t a strong cause of their children being heavier as teenagers.’

According to the authors, their results suggested that ‘higher maternal pre-/early-pregnancy BMI is not a key driver of higher adiposity in the next generation’, something that Dr Bond said was ‘important to know’.

The authors concluded that their findings ‘support interventions that target the whole population for reducing overweight and obesity, rather than a specific focus on women of reproductive age’.

Dr Bond commented that ‘it isn’t enough to just focus on women entering pregnancy.’ However, he added: ‘There is good evidence that maternal obesity causes other health problems for mothers and babies, so prospective mothers should still be encouraged and supported to maintain a healthy weight’.

This article was originally published on Medscape, part of the Medscape Professional Network.

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