Mothers who are obese while pregnant have children with heart problems, study in mice says

Pregnant women who eat a diet high in fat and sugar could have children with heart problems, a new study finds.

Researchers say that, in a study conducted on mice, mouse mothers who ate an unhealthy diet before and during pregnancy had offspring with weak hearts. 

Surprisingly, these health issues lasted for at least three generations, even if the younger mice were not obese and ate a diet of standard mouse chow.

The team, from the Washington University School of Medicine in St Louis, says its findings show how important it is for women to maintain a healthy weight both before becoming pregnant and while pregnant.

A new study from the Washington University School of Medicine in St Louis found that obese mice mothers who eat high-fat, high-sugar diet have children with heart problems (file image)

Researchers found that most of the children of obese mouse mothers had an increase in weight of the left ventricle, which pumps blood out of the heart.

In humans, excess left ventricle weight is often a sign of a weak heart muscle, which can lead to heart failure.

Additionally, the team found that the heart problems were less evident in the female offspring of the younger generation of mice.  

‘The cardiac abnormalities seem to dissipate somewhat over the generations, which is intriguing,’ said co-senior author Dr Abhinav Diwan, an associate professor of medicine at Washington University. 

‘There were also differences in male and female hearts that we can’t explain yet. In many ways, this study presents more questions than it answers, and we plan to continue studying these mice to help answer them.’

To see if the problem was with the obese mother herself or her reproductive system, the team implanted fertilized eggs from obese mice into normal-weight mice. 

However, these offspring had the same heart problems, which shows the health issues were from the egg and not from environmental factors.

The team also found that these heart problems were not just passed down to offspring from their mothers.

Researchers saw that the obese mothers’ male children, who mated with females fed a standard chow diet, had children with the same heart problems. 

Changes were specifically seen in mitochondria, tiny ‘power stations’ that fuel cells.  

This was surprising because, at least in humans, all diseases inherited from mothers are mitochondrial disorders, according to the United Mitochondrial Disease Foundation.

This is because mitochondrial DNA is only passed down from the mother.

‘We know that obesity in pregnant mothers raises the risk of future heart problems for her children,’ said co-senior author Dr Kelle Moley, a professor of obstetrics and gynecology at Washington University. 

‘Now that we’ve shown that mouse fathers pass this down as well, we have to start studying changes in the DNA of the nucleus in both the egg and the sperm to make sure we understand all the contributing factors.’ 

The team believes that the problems with heart mitochondria are due to epigenetic changes in the DNA of the eggs of obese mothers.

Epigenetics is the study of inheritable traits that are carried outside the genome.

They believe that these changes are then carried into the cell of all offspring, male or female.   

The researchers plan to begin new studies soon, but stress that women must follow a healthy lifestyle before and during pregnancy.

‘A big question that people may have is: “What can I do if my grandmother or great-grandmother was obese?”‘ said first author Dr Jeremie Ferey, a postdoctoral research scholar at Washington University. 

‘We need more studies to learn if it’s possible to reverse these mitochondrial defects, but in general, exercise and a healthy diet are always important for heart health.’