In utero and lactational exposure to the Selective Serotonin Reuptake Inhibitor fluoxetine compromises pup bones at weaning

Selective Serotonin Reuptake Inhibitors (SSRIs) such as fluoxetine are widely prescribed to pregnant and breastfeeding women, yet the effects of peripartum SSRI exposure on neonatal bone are not known. In adult populations, SSRI use is associated with compromised bone health, and infants exposed to in utero SSRIs have a smaller head circumference and are shorter, suggesting possible effects on longitudinal growth. Yet no study to date has examined the effects of peripartum SSRIs on long bone growth or mass. We used microCT to determine the outcomes of in utero and lactational SSRI exposure on C57BL6 pup bone microarchitecture. We found that peripartum exposure to 20 mg/kg fluoxetine reduced femoral bone mineral density and bone volume fraction, negatively impacted trabecular and cortical parameters, and resulted in shorter femurs on postnatal day 21. Although SSRIs are considered the first-choice antidepressant for pregnant and lactating women due to a low side effect profile, SSRI exposure may compromise fetal and neonatal bone development.