Flu in early pregnancy can double risk of heart defects

FLU in the early stages of pregnancy can more than double the risk of a baby having cleft lip, heart defects or spina bifida, according to a study.

On the back of the research findings, medical experts are now urging “every mum to be” to get a flu vaccine.

The study, which analysed 10,000 pieces of research and almost 100,000 births, found that in some cases having flu in the first trimester even increased the risk to an unborn baby four-fold.

The most common non-chromosomal congenital anomalies were neural tube defects – such as spina bifida and other developmental brain disorders – cleft lip and palate and congenital heart defects. The first study, which is the first focused exclusively on complications of first-trimester influenza, was carried out by researchers from Semmelweis University, Budapest.

A total of 85,855 births were analysed for women aged 20 to 45.

The results show the total risk of “congenital anomalies” can increase by 50 per cent on average if a mother-to-be catches the flu in the first trimester, compared to a healthy pregnancy. In a more detailed comparison, the risk of neural tube defects can increase by an average of 148 per cent (2.48 times). The significance of neural tube defects is considerable, as they are among the most common causes of genetic abortions.

On average, the risk of developing cleft lip and palate can increase by a similar amount, also 2.48 times.

These children often struggle with feeding difficulties and may develop hearing loss and speech problems.

The third large group is congenital heart defects, which can increase by an average of 63 per cent (1.63 times). Within this, the chance of developing aortic coarctation (narrowing of the aorta) can increase up to four times because of first-trimester maternal influenza infection. Some studies also reported a higher risk of limb development and eye anomalies.

Dr Akos Matrai, assistant lecturer in the department of obstetrics and gynaecology at Semmelweis University, said: “Pregnancy complications caused by viral infections have been the focus of attention in recent years due to Covid19, and there are concerns we might face similar pandemics in the future.

“In our study, we analysed how firsttrimester influenza could affect newborns. The first three months are crucial as most of their organs develop.”

Prof Nandor Acs at Semmelweis, added: “The importance of prevention cannot be emphasised enough.

“Our results show that first-trimester flu can have serious implications as it is the most critical period in the development of the foetus. Therefore, we strongly recommend that every mumto-be get the flu vaccine, even in the planning stages of pregnancy.”

Previous studies have indicated it is not the influenza virus itself but the fever that can cause complications.

The findings are published in Viruses.