Mothers who are overweight or obese while pregnant can cause babies to be born larger, according to a new study.
New research has found that being overweight or obese during pregnancy can cause babies to be born larger.
The study, led by the universities of Bristol and Exeter, also found that mothers with a higher blood sugar level – even within a healthy range – tend to have bigger babies.
However, having higher blood pressure while pregnant can cause newborn babies to be smaller.
It has long been known that women who are overweight or who have diabetes in pregnancy tend to have bigger babies.
Previously though, it had been unclear whether the size of the baby has been caused by these characteristics in the mother, or what factors might be important in linking a mother’s size to that of her babies.
The international research collaboration has shown that excess weight and higher glucose levels in mothers can cause their babies to be born heavier.
Dr Rachel Freathy, of the University of Exeter Medical School, who co-led the study, said: “Being born very large or very small can carry health risks for a newborn baby, particularly when that’s at the extreme end of the spectrum.
“Higher and lower birth weights are also associated with diseases such as Type 2 diabetes later on in life.
“Understanding which characteristics of a mother influence the birth weight of her offspring, may eventually help us to tailor management of a healthy pregnancy and reduce the number of babies born too large or too small.”
The researchers used data from more than 30,000 healthy women and their babies across 18 studies.
They examined genetic variants associated with mothers’ body mass index, such as: blood glucose and lipid levels and blood pressure. They also studied the weight of all the babies at birth.
A previous study found that stressed-out fathers-to-be could pass on an increased risk of diabetes to their children.
Scientists at the Shanghai Jiao Tong University School of Medicine found stress hormones cause a change in sperm that gives offspring high blood sugar.
This research involved male mice, but it was believed that the findings may apply to humans as well.