Some, but not all, studies have demonstrated an increased risk of miscarriage among women who take antidepressants. However, it has been difficult to determine whether this increased risk was related to exposure to the medication or to exposure to other risk factors, including maternal depression. Several recent studies have been reassuring and indicate that antidepressants do not increase the risk, although women who suffer from mood disorders probably carry a slightly higher risk of miscarriage.

Back in April, we reported on the first of these studies.  This research group analyzed data from over one million pregnancies included in the Danish Medical Birth Registry and the Danish National Hospital Registry. Data were assessed for 1,005,319 pregnancies, of which 114,721 (11.4%) ended in a spontaneous abortion.   Miscarriage occurred in 12.0% of women with antidepressant exposure and in 11.1% of women with a history of depression but no exposure. Looking only at women with a diagnosis of depression, the adjusted risk ratio (RR) for spontaneous abortion after any antidepressant exposure was 1.00 (95% CI 0.80-1.24). No individual selective serotonin reuptake inhibitor (SSRI) was associated with spontaneous abortions. The researchers thus concluded that a diagnosis of depression – but not exposure to SSRI – is associated with a slightly higher risk of miscarriage.

The second study also used Danish registries, identifying all registered pregnancies in Denmark from 1997 to 2010, using the Medical Birth Registry, and all records and the National Hospital Register. Data on SSRI use were gathered from the National Prescription Register. The researchers identified 1,279,840 pregnancies (911,569 births, 142,093 miscarriages, 226,178 induced abortions).

Of the 22,884 exposed to an SSRI during the first 35 days of pregnancy, 12.6% (2,883) ended in miscarriage compared with 11.1% among unexposed. The adjusted odds ratio (OR) of having a miscarriage after exposure to an SSRI was 1.27 (95% confidence interval [CI] 1.22-1.33) compared with unexposed. However, when they looked at women who discontinued SSRI treatment 3-12 months before pregnancy, they found that this group also had an increased risk of having a miscarriage compared to unexposed women (OR=1.24, 95% CI 1.18-1.30).

Both of these studies are consistent with a meta-analysis which demonstrated no significant association between antidepressant exposure and spontaneous abortion.

Based on these findings, we can conclude that for women taking antidepressants prior to pregnancy, stopping or tapering off the medication does not appreciably affect their risk of miscarriage.

Ruta Nonacs, MD PhD

Andersen JT, Andersen NL, Horwitz H, Poulsen HE, Jimenez-Solem E. Exposure to Selective Serotonin Reuptake Inhibitors in Early Pregnancy and the Risk of Miscarriage.  Obstet Gynecol. 2014 Sep 5.

Kjaersgaard MI, Parner ET, Vestergaard M, et al.  Prenatal antidepressant exposure and risk of spontaneous abortion – a population-based study.  PLoS One. 2013 Aug 28; 8(8):e72095.

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