Is Remeron (Mirtazapine) Safe During Pregnancy?

What does the evidence say about remeron during pregnancy?

1. In the largest study to date, a Danish nationwide cohort of nearly 2,000 mirtazapine-exposed pregnancies, 3.5% of exposed children had a major congenital malformation compared with 4.3% of unexposed children, and researchers concluded mirtazapine exposure was not associated with a higher rate of major birth defects, miscarriage, stillbirth, or neonatal death. 1
2. Studies covering nearly 5,000 mirtazapine-exposed pregnancies overall have not found an increased chance of birth defects above the general population's baseline rate of about 3%. 2
3. Taking mirtazapine throughout pregnancy can cause temporary newborn symptoms sometimes called neonatal adaptation, including sensitivity to light and sound, a fast heart rate, tremors, and trouble regulating body temperature, which usually resolve on their own though some infants are monitored in a special care nursery as a precaution. 3
4. An exclusively breastfed infant receives about 1.5% of the mother's weight-adjusted mirtazapine dose on average, a low enough relative infant dose that available data describe breastfeeding as compatible with mirtazapine use, especially once a baby is past 2 months old. 4
5. Mirtazapine concentrates somewhat more in hindmilk than foremilk, roughly 2.3 times as much in the small samples studied, so nursing babies may still be watched for behavioral side effects and steady weight gain even though serious effects haven't been reported. 4

Is remeron safe in each trimester?

• First trimester. In the first trimester, the largest study to date, a Danish nationwide cohort of nearly 2,000 exposed pregnancies, found no higher rate of major birth defects with mirtazapine: 3.5% among exposed pregnancies versus 4.3% among unexposed, a difference researchers considered reassuring rather than concerning.
• Second trimester. By the second trimester, the main conversation shifts to weighing the benefits of staying on mirtazapine for depression against any risks, since untreated depression itself is linked to preterm birth and low birth weight.
• Third trimester. In the third trimester, continuous use through delivery can cause temporary symptoms in the newborn, like jitteriness, a fast heart rate, trouble regulating temperature, or sensitivity to light and sound. These usually resolve on their own, though some babies are watched a bit longer after birth as a precaution.