According to a new study in the February issue of the Endocrine Society's Journal of Clinical Endocrinology & Metabolism (JCEM), women taking commonly used forms of antidepressant drugs may experience delayed lactation after giving birth and may need additional support to achieve their breastfeeding goals.

Breastfeeding benefits both infants and mothers in many ways as breast milk is easy to digest and contains antibodies that can protect infants from bacterial and viral infections. The World Health Organization recommends that infants should be exclusively breastfed for the first six months of life. This new study shows that certain common antidepressant drugs may be linked to a common difficulty experienced by new mothers known as delayed secretory activation, defined as a delay in the initiation of full milk secretion.

"The breasts are serotonin-regulated glands, meaning the breasts' ability to secrete milk at the right time is closely related to the body's production and regulation of the hormone serotonin," said Nelson Horseman, Ph.D., of the University of Cincinnati and co-author of the study. "Common antidepressant drugs like fluoxetine, sertraline and paroxetine are known as selective serotonin reuptake inhibitor (SSRI) drugs and while they can affect mood, emotion and sleep they may also impact serotonin regulation in the breast, placing new mothers at greater risk of a delay in the establishment of a full milk supply."

In this study, researchers examined the effects of SSRI drugs on lactation using laboratory studies of human and animal cell lines and genetically modified mice. Furthermore, an observational study evaluated the impact of SSRI drugs on the onset of milk production in postpartum women. In this study of 431 postpartum women, median onset of lactation was 85.8 hours postpartum for the SSRI-treated mothers and 69.1 hours for mothers not treated with SSRI drugs. Researchers commonly define delayed secretory activation as occurring later than 72 hours postpartum.

"SSRI drugs are very helpful medications for many moms, so understanding and ameliorating difficulties moms experience can help them achieve their goals for breastfeeding their babies," said Horseman. "More human research is needed before we can make specific recommendations regarding SSRI use during breastfeeding."

Other researchers working on the study include: Aaron Marshall, Laura Hernandez and Karen Gregerson of the University of Cincinnati in Ohio; Laurie Nommsen-Rivers of Cincinnati Children's Hospital Medical Center in Ohio; Kathryn Dewey of the University of California at Davis; and Caroline Chantry of the University of California Davis.