Maternal Body Mass Index and the Risk of Childhood Infection

The prevalence of maternal overweight and obesity (OWOB) in pregnancy continues to rise worldwide and now poses a major health risk to both mothers and offspring. There is growing evidence to support a link between maternal OWOB in pregnancy and increased risk of adverse long-term outcomes for offspring, such as obesity, metabolic and cardiovascular disease, poor developmental outcomes and asthma1. There is evidence to suggest that maternal OWOB is also associated with increased infection rates in both individuals and their offspring2,3. However, few studies have looked at this and the results are inconsistent4. Results from animal studies indicate that there are a number of potential mechanisms that may be responsible for the increased risk of infection observed in children of obese mothers and that mechanisms are probably multifactorial and include multiple, complex interactions. Potential pathways identified include: increased maternal inflammation; alterations in gut microbiota diversity; and through changes in maternal metabolism, and placental function, which may result in epigenetic changes5.

In addition to this, excessive gestational weight gain (GWG) may also be a risk factor for adverse long-term offspring outcomes. Whilst a number of studies have identified a positive association between excessive GWG and adverse childhood outcomes, including overweight and obesity, wheezing and asthma6, little is currently known about the relationship between GWG and childhood infection. One study conducted in the UK found no relationship between GWG and lower respiratory tract infections (LRTI) during the first year of life7. However, it is not clear how many women were in each GWG category and incidences of LRTI were self-reported by the mother. Interestingly, a number of studies have indicated that excessive GWG is less important compared to maternal pre-pregnancy obesity. Whether this is a result of obese women generally having a lower proportional change in weight, even when the amount of weight gained is considered excessive, is unknown.

There is a growing body of evidence to suggest that mode of delivery8, antibiotic use during pregnancy and delivery, and breastfeeding all influence offspring microbiota9. As the obesity trend doesn’t appear to be reversing, they may act as potential targets for intervention to mitigate some of the associated harms. Therefore, it is important that we understand how these factors can affect childhood health in the presence of maternal overweight or obesity. Maternal obesity is also associated with social deprivation; women of lower socio-economic status (SES) are more likely to be overweight or obese10. As SES is also a risk factor for long-term health, it is important to attempt to disentangle the relationships between social deprivation, maternal obesity and childhood health outcomes.