Oxytocin during pregnancy and early postpartum: individual patterns and maternal-fetal attachment.

Oxytocin (OT), a nanopeptide hormone, plays a role in the emergence of maternal behavior, yet few studies examined OT in humans across pregnancy and the postpartum. We followed healthy women at three points: first trimester of pregnancy, third trimester, and first postpartum month. Plasma OT levels showed high individual stability. A third of the sample showed consistent OT levels, whereas others showed increasing or decreasing trends or peak in late pregnancy. The increase in OT from early to late pregnancy correlated with higher maternal-fetal bonding. These data may help set standards for OT levels and underscore links with maternal-infant attachment.