There's been a flurry of recent headlines about giant babies born around the world, weighing in at 13 pounds or more. One British baby, born in March via vaginal delivery, clocked in at a whopping 15 pounds.
Along with the risk of a difficult birth, there is the impact on the health of the babies once they are born, says Dr. Irina Burd, an assistant professor of gynecology and obstetrics and neurology and director of the integrated research center for fetal medicine at Johns Hopkins Medicine.
It's not uncommon for overweight moms to have diabetes or to develop it during pregnancy. And some of the high blood sugar in the mom flows through the placenta to the baby. That, in turn, forces the baby's pancreas to pump up insulin production, which can leave babies with low blood sugar after they are born, Burd says.
Another problem is that sugar acts like a growth factor, and not all the growth is in sync, says Dr. Hyagriv Simhan, chief of maternal fetal medicine and vice chair for obstetrics at McGee Women's Hospital at the University of Pittsburgh Medical Center.
"In some ways very large babies look more mature because of their size," Simhan adds. "But in terms of their lungs, they may be immature."
Even more concerning are the effects felt by big babies as they grow up. "So they're not just obese at delivery, but there are epigenetic changes that program them for the rest of their lives," Burd says. And those include a heightened risk for obesity and cancer, she says.
That's why doctors have tried to encourage pregnant patients who are obese to gain very little weight during pregnancy.
Newborn baby on scale, via Shutterstock