All psychotropic medications cross the placenta, are present in amniotic fluid and can enter human breast milk. Therefore the decision about the use of antidepressant medication during pregnancy or breastfeeding is always a risk/benefit analysis. There are risks to the fetus from a mother suffering from major depressive illness. Among depressed pregnant women there’s an increased incidence of low birth weight, decreased fetal growth, premature birth and postnatal complications. The newborn is at increased risk for elevated cortisol and catecholamine levels, infant crying, and admission to neonatal intensive care units. Maternal depression is associated with more life stress, less social support, increased financial difficulties, smoking, alcohol and drug use, all of which affect the neonate.
None of the antidepressants are considered major teratogens although there have been reports of very minor increases in some birth defects with SSRI use. Most notable is a slight increase in cardiac defects associated with paroxetine. Late exposure can result in jitteriness, mild respiratory distress and transient tachypnea of the newborn, weak cry, poor tone and neonatal ICU admission.
For breastfeeding mothers, all antidepressants are present in breast milk but for the most part in very low levels (lower than the amount crossing the placenta during pregnancy) that have not been considered clinically relevant. One should always monitor the infant however for possible effects of antidepressant use.
The bottom line is that paroxetine should probably be avoided if possible during pregnancy. Use single medication at higher doses rather than combinations of medications. There’s no benefit to measuring serum levels of anti-depressants in breast milk as the levels are too low to be helpful. The decisions must be made on an individual basis for each woman — never forgetting that untreated maternal depression carries its own risks.