By LEE BOWMAN
July 23, 2004
Overweight and obese women tend to have a weaker biological response to their babies suckling, which might be the chief reason that such mothers are more likely to stop breast-feeding earlier than normal-weight moms, according to a nutrition expert.
Kathleen Rasmussen, a professor of nutrition sciences at Cornell University who has been studying breast-feeding patterns among overweight women for more than a decade, said overweight and obese women produce less prolactin, a hormone made by the pituitary gland that stimulates the breast's milk glands to produce milk soon after birth.
"This lower prolactin response to suckling would be expected to compromise the ability of overweight and obese women to produce milk and over time, lead to a significantly shorter period of breastfeeding," she said.
Breast-feeding in the first six months to a year of an infant's life is important because breast milk helps protect babies from a variety of childhood illnesses by boosting the immune system and promoting development of other key systems of the body, including the brain.
Government public health goals call for 75 percent of new mothers to breast-feed, with 50 percent continuing for six months and 25 percent for 12 months.
"We're a long way from those goals nationally," Rasmussen said. "At the present time, 64 percent of women breast-feed right after pregnancy, but only 29 percent continue for at least six months."
In 1997, Rasmussen reported that overweight and obese mothers, as defined by their body mass index, were 2.5 and 3.6 times, respectively, less successful in starting breast-feeding than mothers who were not overweight. The heavier the mother, the less successful she was at breast-feeding a child.
In 2001, Rasmussen reported that normal-weight women who gain more than 24 to 35 pounds during pregnancy, as recommended by scientific guidelines, are 74 percent more likely to be unsuccessful at breast-feeding than mothers who don't exceed the weight-gain guidelines.
Rasmussen had theorized that the delayed release of the hormone progesterone, which helps maintain pregnancy, might cause the delay in milk production.
But in measuring levels of prolactin and progesterone in 40 mothers just before and 30 minutes after breast-feeding, taken 48 hours post-delivery and then a week later, she found the heavier women producing significantly less prolactin right after birth, and moderately less a week later than women who were not overweight.
She and co-author Dr. Chris Kjolhede of Bassett Hospital in Cooperstown, N.Y., reported the latest findings online in the journal Pediatrics earlier this year.
Rasmussen said while women should try to begin with and keep a healthy weight through pregnancy, not all are able to do so. She urges those who are overweight to consult with a lactation expert and make sure they get follow-up support to help in their efforts to breast-feed after they go home from the hospital with their newborn.