Maternal obesity raises the risk of a number of health conditions for offspring that can persist well into adulthood, including heart disease and asthma. Now, a new study reveals why this may be; maternal obesity weakens an infant’s immune system at the time of birth, increasing their susceptibility to illness.
Study leader Ilhem Messaoudi, of the University of California-Riverside, and colleagues publish their findings in the journal Pediatric Allergy and Immunology.
Around 60% of women of childbearing age in the US are overweight or obese – a risk factor for poor health during pregnancy.
Maternal obesity has been linked to increased risk of gestational diabetes, preeclampsia and preterm birth. Studies have also suggested a greater risk of birth defects, type 2 diabetes, asthma and heart disease among children born to obese mothers.
While previous research has indicated that maternal obesity dysregulates an infant’s immune system to make them more prone to illness, Messaoudi and colleagues say the mechanisms behind this are poorly understood.
For their study, the team set out to investigate what effect maternal body weight has on the immune system of newborns.
To reach their findings, the researchers enrolled 39 mothers and their infants to the study. Each mother’s body mass index (BMI) was recorded – calculated by their height and weight – before they were allocated to one of three groups: lean, overweight or obese. Overweight was defined as a BMI of 25-29.9, while obese was defined as a BMI of 30 or higher.
Eleven of the mothers were lean, 14 were overweight and 14 were obese. All women were nonsmokers and had no complications during pregnancy.
The team collected umbilical cord blood samples from the mothers’ infants, assessing the samples for immune cell population and circulation.
Compared with infants born to lean mothers, the researchers found that specific immune cells – monocytes and dendritic cells – among infants born to obese mothers showed much lower responses to bacterial antigens.
“Such babies also showed a reduction in CD4 T cells,” adds Messaoudi. “Both of these changes could result in compromised responses to infection and vaccination.”
The umbilical cord blood samples also showed lower levels of eosinophils (cells involved in allergic response and asthma development) among infants born to obese mothers. The researchers say these cells may have already traveled into the infants’ lungs, which may explain why children born to obese mothers are at greater risk of asthma later in life.
The team says their study shows that maternal obesity can influence changes in an infant’s immune system that are detectable at birth and may persist throughout their lifetime.
Messaoudi adds that the findings raise a number of questions about how children should be vaccinated:
“This could change how we respond to vaccination and how we respond to asthma-inducing environmental antigens. As we know, in the first 2 years of life, children typically receive plenty of vaccines.
“The questions that arise are: Are the responses to vaccines in infants born to obese moms also impaired in the first 2 years of life? Should we change how often we vaccinate children born to obese moms? Should we change practices of how much and how often we vaccinate?”
While further studies are warranted to assess the link between maternal obesity and the neonatal immune system, Messaoudi believes their findings indicate that more focus is needed on combating weight gain before and during pregnancy.
“When moms come in for prenatal visits, doctors tell them about smoking, recreational drug use, and alcohol. But they should be talking also about weight and weight management,” says Messaoudi.
“Obesity has serious repercussions for maternal health. It is associated with low fertility and success with pregnancy,” she adds. “Rates of gestational diabetes, preeclampsia, placental abruption – all of these risks increase dramatically with weight gain and obesity. So it is important to talk to your doctor about ideal weight entering into pregnancy and throughout pregnancy.”
In December 2014, Medical News Today reported on a study published in The BMJ revealing that overweight or obesity in the early stages of pregnancy may raise the risk of infant mortality.