Objective: Selective serotonin reuptake inhibitors are commonly used for the treatment of pregnancy-related and postnatal depression. However, only a few studies have evaluated the passage of these drugs into human milk, often with conflicting results. Here, we sought to evaluate the passage of selective serotonin reuptake inhibitors into human milk in the first days after delivery and their potential association with neonatal outcomes. Study design: The passage of selective serotonin reuptake inhibitors into human milk was expressed both as percentage of milk-to-plasma ratio of drug concentrations and as the relative infant dose (RID). Selective serotonin reuptake inhibitors were quantified by high-performance liquid chromatography combined with mass spectrometry. Results: Nineteen women treated with selective serotonin reuptake inhibitors during the third trimester of pregnancy and lactation were considered. Human milk-to-plasma ratios ranged from 51.1% to 703.4%. The patients had a median RID of 1.5%, with differences among the selective serotonin reuptake inhibitors. All newborns had been breastfed from birth up to day three of life. At 1 week follow up, 58% of infants were breastfed, 37% were complementary fed, and 5% were formula fed. No side effects due to passage of selective serotonin reuptake inhibitors into human milk were found. Conclusions: Selective serotonin reuptake inhibitors were detected in human milk, with milk-to-plasma ratios which in some cases exceeded 100%. Given the need for maternal therapy and the low incidence of neonatal adverse events, it is advisable not to preclude breastfeeding a priori but recommend it with careful follow-up.
Keywords: Human milk; lactation; pregnancy; selective serotonin reuptake inhibitors (SSRI).