Maternal prenatal plasma oxytocin is positively associated with prenatal psychological symptoms, but method of immunoassay extraction may affect results.

We examined associations between prenatal plasma oxytocin levels and depressive symptoms, state anxiety, and pregnancy anxiety in 75 women who visited the laboratory with their partners during mid-to-late pregnancy and engaged in relationship discussion tasks prior to a blood draw. Given controversy in the literature regarding oxytocin measurement, we compared two widely-used immunoassay approaches (with and without extraction prior to immunoassay). Levels of immunoreactive oxytocin measured with and without extraction were not correlated with each other. However, both extracted and unextracted oxytocin were positively associated with women's prenatal depressive symptoms in a model that controlled for pregnancy stage and body mass index. Only unextracted oxytocin was associated with state anxiety and pregnancy-specific anxiety. In summary, elevated plasma oxytocin levels in expectant mothers might indicate risk for mental health symptoms during the prenatal period, but results for anxiety are mixed and appear to depend on the immunoassay approach employed.