Although the first few days of breastfeeding may be difficult, many women overcome the complications and eventually find their nursing experience to be among the most loving and satisfying in their lives. Women who experience a low milk supply often worry they are somehow inadequate, while also feeling heartbroken over their loss. Now, two new studies conducted by Cincinnati Children's Hospital Medical Center researchers have gotten to the roots of low milk supply — the same factors contributing to diabetes may cause a insufficient milk in new mothers. In fact, new mothers diagnosed with lower-than-average milk were found to be 2.5 times more likely to have problems with insulin metabolism (gestational diabetes) compared to other new mothers.

“One consequence of the obesity epidemic is that nearly one out of every four reproductive-aged women is pre-diabetic,” said Dr. Laurie Nommsen-Rivers, a researcher at the Cincinnati Children's Perinatal Institute. “Research to inform how to support lactation success in this vulnerable group of women is urgently needed."  Nommsen-Rivers presented her work at the annual meeting of the Pediatric Academic Societies.

The Best Food

Scientists have described breast milk as the perfect meal. Not only does it provide a baby with all that is needed immunologically, but it is also tuned to the sensory needs of a baby. The first milk, for instance, is more watery and so addresses a baby's thirst. Yet as the nursing continues, the milk becomes higher in fat and ends at its creamiest texture. Even more wondrous is the fact that breast milk changes throughout the day and also over time. In the evening, for instance, breast milk has more sedating properties when compared to the morning, and as a baby grows, mother’s milk takes on nutritional qualities appropriate for that phase of development. For these reasons, breast milk is quite simply the best food a mother could possibly give her baby.

A team of researchers led by senior author Nommsen-Rivers gathered and analyzed the records of 561 women seeking help for a breastfeeding problem at Cincinnati Children's Breastfeeding Medicine Clinic. After conducting various studies with the data, Nommsen-Rivers found that elevated body mass index (BMI), elevated fasting insulin, insulin resistance and, especially, elevated fasting plasma glucose in the pre-diabetic range were all predictors of poor milk supply in women attempting to exclusively breastfeed. In fact, the team proved that postpartum metabolic health also affected lactation sufficiency even among those women who did not experience diabetes in pregnancy.

Gestational diabetes, which causes high blood sugar during pregnancy (and in many cases disappears after the baby's birth), affects about 18 percent of all pregnancies. Risk factors include excess weight, being older than 25, a family or personal history of pre-diabetes, and non-white race (with more black, Hispanic, Native American, and Asian women developing the condition). Although the exact cause is unknown, researchers believe hormones from the placenta block the action of the mother's insulin in her body. This insulin resistance means a mother-to-be may need up to three times as much insulin otherwise glucose builds up in the blood (hyperglycemia). Through proper diet, exercising, and, when necessary, medication, expectant mothers can in many cases control gestational diabetes.

Nommsen-Rivers and her team are now planning to conduct a clinical trial of metformin, a drug used to control blood sugar in type 2 diabetes. They are hoping to understand whether metformin, by improving insulin action in the mammary gland, will boost milk production in pre-diabetic mothers. "We need to better understand how we can identify mothers at risk for low milk supply and how best to support them in meeting their breastfeeding goals," said Dr. Sarah Riddle, a pediatrician at the Center for Breastfeeding Medicine and lead author of the study. "We also need to develop targeted therapies to support lactation success in women with a history of glucose intolerance."