Obesity increases the odds of multiple pregnancies: A nationwide register‐based cohort study in Finland

Abstract

The effects of overweight and obesity on the risk of multiple pregnancies have been studied. Multiple pregnancies are relatively rare, making the phenomenon challenging to study without proper data.Only a few studies have investigated the effects of a higher body mass index (BMI; calculated as weight in kilograms divided by the square of height in meters) on the risk of multiple pregnancies. A 2005 study that analyzed the US population found that women with a higher BMI had an increased risk of having twins. 1 The same study found that the risk of dizygous twins was higher, but the risk of homozygous twins was not increased. 1 Another study using a twin register in the Netherlands also found higher risk for multiple pregnancies in the obese population. 2 According to a large National