Babies born to obese pregnant women are more likely to develop heart problems and diabetes as adults because of fetal damage caused by their mother’s high-fat, high-energy diet.
That is the groundbreaking finding of a new study published in the journal Journal of Physiology which shows for the first time that maternal obesity alters a critical thyroid hormone in the fetal heart, disrupting its development.
Eating a diet high in fat and sugar during pregnancy also increases the likelihood that the fetus will develop insulin resistance in adulthood, which could trigger diabetes and cause cardiovascular disease, even though babies have a normal birth weight.
Researchers at the University of South Australia identified the link by analysing tissue samples from pregnant baboon foetuses fed a high-fat, high-energy diet at a US biomedical research institute. They then compared these results to foetuses from baboons fed a control diet.
Lead author, University of South Australia PhD candidate Melanie Bertossa, says the findings are significant because they demonstrate a clear link between an unhealthy diet high in saturated fat and sugar and poor cardiovascular health.
“There has long been debate over whether high-fat diets induce a state of hyperthyroidism or hypothyroidism in the fetal heart. Our evidence points to the latter,” says Bertossa.
“We found that a high-fat, high-energy maternal diet reduces levels of the active thyroid hormone T3, which acts as a switch in late gestation, signaling the fetal heart to start preparing for life after birth. Without this signal, the fetal heart develops differently.”
Bertossa says diets high in fat and sugar can alter molecular pathways involved in insulin signaling and critical proteins involved in glucose uptake in the fetal heart. This increases the risk of cardiac insulin resistance, which often leads to diabetes in adulthood.
“We are born with all the heart cells we will ever have. The heart does not produce enough new heart muscle cells after birth to repair any damage, so changes that negatively affect these cells before birth could persist throughout life.
“These permanent changes could cause further deterioration in heart health once children reach adolescence and adulthood, when the heart begins to age.”
Lead author, UniSA Physiology Professor Janna Morrison, says the study demonstrates the importance of good maternal nutrition in the pre-pregnancy period, not only for the sake of the mother but also for the health of the baby.
“Poor cardiac outcomes were seen in babies who were of normal birth weight, a sign that should guide future clinical practice,” says Professor Morrison.
“Cardiometabolic health screening should be performed on all babies born from these types of pregnancies, not just those who are born too small or too large, in order to detect the risks of heart disease earlier.”
Professor Morrison says that if rising rates of high-fat and high-sugar diets are not addressed, more people will develop health complications such as diabetes and cardiovascular disease, which could result in shorter lives in the coming decades.
“Hopefully, with the knowledge we now have about the negative health impacts of obesity, there is a chance to change this trajectory.”
Researchers are currently conducting long-term studies of babies born to women on high-fat, high-energy diets to follow their health over decades.