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February 2010 Issue

New UC-led research suggests that some antidepressants can inhibit serotonin reuptake in mammary glands, causing a delay in lactation.
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Study Finds Common Antidepressant Drugs Linked to Delays in Lactation After Birth

Published February 2010

Women who take a commonly used form of antidepressant drugs may experience delays in lactation after giving birth and may need additional support to meet their breastfeeding goals, a study led by UC researchers has found.

The findings are reported in the February 2010 edition of the Journal of Clinical Endocrinology and Metabolism, a peer-reviewed publication of the Endocrine Society. Nelson Horseman, PhD, a professor in the department of molecular and cellular physiology at the UC College of Medicine, is the study’s corresponding author.

The World Health Organization recommends that infants should be exclusively breastfed for the first six months of life to achieve optimal growth, development and health. Breast milk is easy to digest and contains antibodies that can protect infants from bacterial and viral infections.

Antidepressants such as fluoxetine (brand name Prozac), sertraline (Zoloft) and paroxetine (Paxil) are known as selective serotonin reuptake inhibitor (SSRI) drugs. SSRIs work by allowing the body to make the best use of reduced amounts of serotonin, which is a neurotransmitter known to affect mood, emotion, sleep and appetite.

Previous research published by Horseman and his team showed that serotonin plays a role in mammary gland development.

In the current study, inhibiting serotonin reuptake in mammary cells altered their function and delayed lactation. De-layed lactation is commonly de-fined as occurring later than 72 hours after childbirth, and mothers who experience such a delay are at significantly greater risk for early cessation of breastfeeding.

Researchers at UC’s College of Medicine and James L. Winkle College of Pharmacy, Cincinnati Children’s Hospital Medical Center and the University of California Davis examined the effect of SSRI drugs on lactation using laboratory studies of human and animal cell lines and genetically modified mice and an observational study of the onset of milk production in postpartum women.

In the study of 431 postpartum women, median onset of lactation was 85.8 hours postpartum for the SSRI-treated mothers, versus 69.1 hours for the non-SSRI group.

“We found that women who were taking these drugs were essentially having a harder time achieving lactation,” says Horseman. “This is important because correctly prescribed SSRIs are helpful medications for many mothers, and understanding and ameliorating the difficulties they might experience can help them achieve their goals for breastfeeding their babies.

“While women on SSRIs may be at a greater risk of a delay in the establishment of a full milk supply, with proper supportive care from pediatricians, nurses and lactation consultants those difficulties appear to be only temporary,” Horseman adds.

Horseman says further research with larger numbers of women is needed, along with studies comparing the effects of different antidepressant medications.

Collaborating with Horseman were Karen Gregerson, an associate professor in UC’s James L. Winkle College of Pharmacy; Aaron Marshall, PhD, and Laura Hernandez, PhD, of UC’s department of molecular and cellular physiology; Laurie Nommsen-Rivers, PhD, of Cincinnati Children’s Hospital Medical Center’s division of neonatology; Kathryn Dewey, PhD, of the University of California Davis department of nutrition; and Caroline Chantry, MD, of the University of California Davis department of pediatrics.

Horseman, Marshall and Hernandez are inventors of a provisional patent related to their research.

The study was supported in part by grants from the National Institutes of Health, the U.S. Department of Agriculture’s Co-operative State Research, Education and Extension Service and the U.S. Department of Heath and Human Services’ Maternal and Child Health Bureau. The researchers reported no conflicts.

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