BOSTON, Aug. 18 (UPI) -- News stories of babies born weighing 13 pounds or more are common in the developed world, but experts say U.S. maternal obesity has long been an issue.
This year, a German baby girl weighed more than 13-and-a-half pounds; a California woman had a 13-pound, 10-ounce girl; last week, a British mom in Spain gave birth to a 13-pound, 11-ounce daughter and in March a British mother gave birth to a 15-pound, 7-ounce son, NBC News reported.
In the developed world, there has been a 15 percent to 25 percent increase in babies weighing 8 pounds, 13 ounces or more -- the weight a baby is considered oversized -- in the past two to three decades, a study in The Lancet said.
The journal article linked overweight mothers in China with a 7 percent rate of oversized babies, while in India, where maternal obesity was low, only 0.5 percent of newborns were very large.
However, in the United States doctors have become more aggressive, by inducing labor earlier than they did in the past before a baby becomes too heavy.
"In the past, say the '80s, women often weren't considered for induction unless they didn't go into labor on their own by 41 to 43 weeks," Dr. Robert Barbieri, a professor of obstetrics and gynecology at the Harvard Medical School and chief of obstetrics and gynecology at Harvard's Brigham and Women's Hospital, told NBC News. "Now it's between 39 and 41 weeks. So babies don't have a chance to get bigger in those later gestational weeks."
By 2006, there was an almost 100 percent drop in the number of births that went beyond 41 weeks, a Harvard study said.
However, 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, told NBC News very large babies look more mature because of their size, but "in terms of their lungs, they may be immature."