0755 GMT November 29, 2020
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Study author Dr. Songzan Chen of Zhejiang University, Hangzhou, China said: "Our results suggest that the risk of atrial fibrillation in adulthood may be higher for large newborns (over 4,000 grams 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 checkups during pregnancy, particularly for women who are overweight, obese or have diabetes."
He added: "People born with a high weight should adopt a healthy lifestyle to lower their likelihood of developing the heart rhythm disorder."
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. This study investigated the lifetime causal effect of birth weight on the risk of atrial fibrillation.
The researchers conducted a naturally randomized controlled trial — a technique called Mendelian randomization. First, they used data from 321,223 individuals in a genome-wide association study (GWAS) to identify 132 genetic variants associated with birth weight.6 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).
To conduct the naturally randomized controlled trial, 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 analyzed 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 (about one standard deviation) above the average (3,397 grams) were 30 percent more likely to develop the heart rhythm disorder (odds ratio = 1.30; 95% confidence interval 1.18-1.44; p=0.0000004).