Research has shown that pregnant women suffering from diabetes or obesity have larger babies on average, but a new study reveals new insights into the mechanisms behind rapid fetal growth. According to a report from UPI, scientists from the University of Cambridge in the U.K. have shown that obesity and diabetes can affect the rate of fetal development beginning in the early phases of pregnancy.

The study, led by senior researcher Dr. Gordon Smith, showed that children of mothers who were obese or had pregnancy-related diabetes were abnormally large by or before the sixth month of pregnancy. The study may lead doctors to reconsider standard diabetes testing procedures, which are typically carried out no sooner than the sixth month of pregnancy.

Smith’s team found that babies of obese or diabetic women were 63 percent more likely to be larger than average around the abdomen by the 20^th week of pregnancy compared to babies born to smaller mothers.

Dr. Smith thinks the current testing benchmark may come too late for some mothers. “Our study shows that the babies of obese women were more likely to be excessively large around the abdomen even as early as 20 weeks into pregnancy,” he said.

Though the American Congress of Obstetricians and Gynecologists recommends early diabetes screening for expecting mothers who are obese, abnormally large infants pose a number of health risks.

High birth weight has been linked to an increased likelihood for the need of a cesarean-section delivery, dangerous low blood sugar levels and trouble breathing after delivery. Research has also shown that heavy babies are more likely to develop obesity and diabetes later on in life.

“Our study suggests that the babies of women subsequently diagnosed with gestational diabetes are already abnormally large by the time their mothers are tested for the disease,” says Dr Ulla Sovio from the Department of Obstetrics and Gynecology at the University of Cambridge. “Given the risk of complications for both mother and child from gestational diabetes, our findings suggest that screening women earlier on in pregnancy may help improve the short and long term outcomes for these women.”

A press release from the University of Cambridge describing the details of the study can be found here.