Children born to women with obesity have higher risk of infection

Children born to mothers with a body mass index (BMI) of 35 or over are at an increased risk of being admitted to hospital with an infection, a new study shows.

The findings, published in BMJ Medicine, highlight the importance of women maintaining a healthy body weight before and after pregnancy. 

In the Bradford-based study, researchers analysed long-term data from nearly 1,000 children born to mothers with BMI ≥35, recording any infections, including those requiring hospital admission, in the first 15 years of the child’s life.

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The rate of admission was 53% higher among children whose mothers had grade 2 or 3 obesity (BMI ≥35) than among those with a mother of healthy weight.

Maternal obesity is on the rise, according to the researchers, with estimates suggesting that nearly one in four mothers will be obese when they give birth by 2030. Since obesity is characterised by chronic inflammation, which can lead to a disordered immune system, as well as changes in gene expression and alterations to the gut microbiome, being overweight has the potential to influence the long-term health of the developing foetus.

To understand how maternal weight during pregnancy can affect infection rates amongst children, the researchers analysed data from Born in Bradford, a longitudinal, multi-ethnic research programme tracking the health and family lives of over 600,000 Bradfordians.

Between 2007 and 2011, 9,540 singleton babies were born to 9,037 mothers at Bradford Royal Infirmary. The children were followed from birth to 15 years of age, examining the total number of hospital admissions related to infections at age <1 year, 1-4 years and 5-15 years. Infections recorded included those of the upper respiratory tract, lower respiratory tract, skin and soft tissue, genitourinary system, gastrointestinal tract, invasive bacterial infections and multisystem viral infections.

Overall, there were 5,009 hospital admissions for infections between birth and the age of 15, with the highest admission rates for infants under one year.

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For children born to mothers of a healthy weight, admission rates for infection were lower than those for children whose mothers had a BMI ≥35, at 39.7 admissions/1,000 person-years compared with 60.7/1,000 person-years, respectively.

After adjusting for potentially influential factors, the children’s infection admission rates were positively associated with the mother’s BMI at birth, across all age groups. However, this was only statistically significant at obesity grades 2-3; these children were 41% more likely to be admitted to hospital for an infection at under one year, and 53% more likely to be admitted for an infection between the ages of 5 and 15, compared with their counterparts.

The observed associations were slightly stronger in boys than in girls, and in Pakistani women than in white British women. Respiratory, gastrointestinal and multisystem viral infections accounted for most of the excess hospital admissions.

Of other potentially modifiable factors that were assessed, Caesarian-section birth accounted for 21% of the association between obesity grades 2-3 and childhood infections during the first five years, and child obesity at age 4-5 for 26% of the association. Breastfeeding for 6 or more weeks and excessive pregnancy weight gain were not significantly associated, however.

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Acknowledging the limitations of this type of observational study, the researchers said: ‘The findings of our study highlight the need for public health campaigns and additional support for healthcare professionals to help women of reproductive age achieve and maintain a healthy body weight.’

They added: ‘Although the results indicated a modest effect of maternal obesity, and only in those with obesity grades 2-3, the potential effect on a large number of children globally is substantial.’