Expectant mothers who are overweight or obese are more likely to give birth to larger babies because of higher blood sugar levels, according to a new study.
British researchers from the University of Exeter and the University of Bristol examined data from more than 30,000 women and found that maternal body mass index, blood sugar level and systolic blood pressure are all significant factors in predicting infant birth weight.
Previous studies show that overweight or diabetic moms were more likely to give birth to larger babies. Lead researcher Jess Tyrrell of the University of Exeter and her team believe the latest study may explain why this happens. According to researchers, the findings are important because it could pave the way to the development of new treatments and interventions to help improve the health of expectant mothers and their babies.
After analyzing results from 18 studies involving 30,487 women who gave birth between the years of 1929 and 2013, researchers found that mothers with higher blood sugar were more likely to have bigger babies. However, levels of fat in maternal blood did not seem to matter. Researchers said this finding is interesting because it goes against previous studies showing that levels of maternal blood lipids related to being overweight influences baby birth weight.
"These results provide evidence that genetically elevated maternal glucose and SBP may have directionally opposite causal associations with birth weight. The estimated associations between these maternal traits and birth weight (either increased or reduced) are substantial and of clinical importance. They support efforts to maintain healthy gestational glucose and blood pressure levels to ensure healthy fetal growth," researchers wrote in the study. "If replicated, these findings may have implications for counseling and managing pregnancies to avoid adverse weight-related birth outcomes."
The study also revealed that expectant mothers with higher blood pressure gave birth to smaller babies. Researchers said this is interesting because overweight or obese individuals are more likely to have higher blood pressure.
"A lot of research into pregnancy and birth weight has been based on observation, but this can make it very difficult to determine what is cause and what is effect, creating a confusing picture for mothers, clinicians and healthcare workers. Our genetic method is more robust, giving clear evidence that mothers' weight, glucose and blood pressure affect the size of the baby," Tyrrell said in a university release.
The findings are published in The Journal of the American Medical Association.
