By Nancy Walsh, Senior Writer, MedPageToday
Reviewed by Dori F. Zaleznik, MD; Associate Clinical Professor of Medicine, Harvard Medical School, Boston.
January 26, 2010
Women taking selective serotonin reuptake inhibitor (SSRI) antidepressants may experience delays in postpartum breast milk production, researchers said.
Delayed secretory activation occurred in 87.5% of a small group of women taking SSRIs, compared with 43.5% of those not taking the drugs (RR 2, 95% CI 1.51 to 2.67, P=0.02), according to Aaron M. Marshall, PhD, of the University of Cincinnati.
The relative risk of delayed activation remained significantly higher (P<0.05) among SSRI users after adjustment for maternal age, obesity, cesarean delivery, infant gestational age, and infant breastfeeding behavior, the researchers reported online in the Journal of Clinical Endocrinology and Metabolism.
An early breastfeeding difficulty faced by many women, particularly those who are primiparous, is milk secretion delayed beyond 72 hours postpartum.
These women also are at risk of early cessation of breastfeeding. In fact, only 11% of mothers in the U.S. breastfeed exclusively for the recommended six months.
Studies in animal models and cell cultures suggested that serotonin (5-HT) is an important local regulator of lactation homeostasis, and the 5-HT transporter is expressed in mammary tissue at the apical membrane of epithelial cells.
Serotonin is controlled intracellularly by a balance between synthesis and degradation, while extracellularly its availability is controlled through recycling by the 5-HT transporter.
The 5-HT transporter also is the target for the most commonly prescribed class of antidepressants in the U.S. and other developed countries. These SSRI antidepressants are typically used to treat postpartum depression.
The investigators conducted in vitro and animal studies to establish that the 5-HT transporter is expressed in breast tissue, particularly in the apical membranes of mammary epithelial cells, and that pharmacologic inhibition of the transporter disrupts tight junctures leading to a local involution-like effect.
To examine the potential effect of SSRI inhibition on milk production in women, Marshall and colleagues enrolled 431 mothers as part of a longitudinal cohort study examining barriers to early lactation success.
All were expecting their first live-born infants, had no known absolute contraindication to breastfeeding, and were at least 19 years old.
Women taking SSRIs were more likely to have scored higher on a depressive symptom scale (as expected), and were somewhat more likely to be obese or to have had a cesarean delivery.
Participating mothers were visited between 72 and 96 hours after giving birth to assess their breastfeeding experience and to determine the timing of secretory activation, and then seen again one week later.
Delayed secretory activation was defined as initiation more than 72 hours postpartum.
Median onset of secretory activation among the SSRI-treated mothers was 85.8 hours compared with 69.1 hours in mothers not using the drugs (P=0.004).
Eight women reported regular use of an SSRI medication. Seven experienced definite delayed secretory activation, and the eighth reported activation at 72 hours and therefore did not meet the defined cutoff for delayed activation.
All women taking SSRIs had experienced secretory activation by their second visit a week after the first interview.
The researchers noted that most studies on the effects of SSRI use during pregnancy and lactation have focused on the risks for developmental defects or whether the drugs passed into milk during lactation.
This study, they said, is the first to report data on another important aspect of SSRI use during the peripartum, the effect on milk production.
They concluded that the risk of delayed secretory activation was twice as great among primiparous women using an SSRI medication, and although the fraction of women taking the drugs was small, the risk was significant and remained so after adjustment for potential confounding factors.
Further examination of this relationship is needed in larger groups of mothers, the researchers said, and in studies to determine if there are differences among the antidepressant medications.
- Explain to interested patients that the use of certain types of antidepressants in the postpartum period may affect the onset of mothers’ milk production.
- But note that this observation was in a study that included only a small number of women using the drugs, and further research is needed.
Primary source: Journal of Clinical Endocrinology and Metabolism
Source reference: Marshall A, et al “Serotonin transport and metabolism in the mammary gland modulates secretory activation and involution” J Clin Endocrin Metab 2009; DOI: 10.1210/jc.2009-1575.