Big babies at higher heart rhythm disorder risk in adulthood

A team of researchers has linked elevated birth weight with developing a common heart rhythm disorder atrial fibrillation later in life.

Chinese researchers from Zhejiang University, Hangzhou, China said that the risk of atrial fibrillation in adulthood may be higher for large newborns (over 4 kilos or 8 pounds 13 ounces) than those with normal birth weight.

"Preventing elevated birth weight could be a novel way to avoid atrial fibrillation in offspring -- for example with a balanced diet and regular check-ups during pregnancy, particularly for women who are overweight, obese or have diabetes," said study author Dr Songzan Chen at the 31st 'Great Wall International Congress of Cardiology' (GW-ICC).

"People born with a high weight should adopt a healthy lifestyle to lower their likelihood of developing the heart rhythm disorder," Chen said.

Atrial fibrillation is the most common heart rhythm disorder, affecting more than 40 million individuals globally.

People with atrial fibrillation have a five times greater risk of having a stroke.

The relationship between birth weight and atrial fibrillation is controversial and this study investigated the lifetime causal effect of birth weight on the risk of atrial fibrillation.

The researchers conducted a naturally randomised controlled trial.

First, they used data from 321,223 individuals in a genome-wide association study (GWAS) to identify 132 genetic variants associated with birth weight.

Next, they identified which of those variants play a role in atrial fibrillation using data from 537,409 participants of the Atrial Fibrillation Consortium (of whom 55,114 had atrial fibrillation and 482,295 did not).

The 132 genetic variants were randomly allocated to the 537,409 participants at conception, giving each individual a birth weight in grams.

The investigators then analysed the association between birth weight and atrial fibrillation.

Elevated birth weight was associated with an increased risk of atrial fibrillation later in life.

Specifically, participants with a birth weight that was 482 grams above the average were 30 per cent more likely to develop the heart rhythm disorder, the study said.

"However, we cannot discount the possibility that adult height and weight may be the reasons for the connection. Birth weight is a robust predictor for adult height, and taller people are more likely to develop atrial fibrillation," Chen noted.

Previous research has shown that the link between birth weight and atrial fibrillation was weaker when adult weight was taken into account.

"This study provides genetic evidence for the association between elevated birth weight and the increased risk of atrial fibrillation," said Professor Guosheng Fu of Sir Run Run Shaw Hospital (SRRSH).