Antidepressant Use in Pregnancy
- March 31, 2023
Depression affects approximately 10% of pregnant people and is associated with adverse parental and foetal outcomes, including compromised parenting, which can impact on child development.(1) Some data suggest that antidepressants may increase the risk of spontaneous abortion, preterm delivery and low birth weight; however, these risks can also be attributed to untreated depression. Selective serotonin reuptake inhibitors (SSRIs) have the most pregnancy safety data.
Risks associated with antidepressant use in pregnancy
|First trimester exposure||Possible adverse foetal and parental outcomes|
|Small increased risk of cardiac malformations OR* 1.25 (95% CI 1.15–1.37; NNH 388).
|SSRIs have been associated with spontaneous abortion, decreased gestational age (usually a few days) and decreased birth weight (mean 175 g).(2)
Late pregnancy exposure:
|venlafaxine||Small increased risk of cardiac malformations OR* 1.3 (95% CI 0.99–1.71).||As for SSRIs.|
|mirtazapine||Fewer data than SSRIs.||Fewer data than SSRIs. Effects similar to SSRIs cannot be excluded.
|Small increased risk of cardiac malformations OR* 1.23 (95% CI 1.01–1.49).||Fewer data than SSRIs. Effects similar to SSRIs cannot be excluded.|
|moclobemide||Fewer data than SSRIs.||Data too limited to fully assess safety.|
|Wide use over several decades.
No increased risk of cardiac malformations OR* 1.02 (95% CI 0.82–1.25).
|Wide use over several decades suggests any risk is very small. Effects similar to SSRIs.|
Long term neurodevelopmental outcomes
Some data suggest that antidepressants may increase the risk of learning and behavioural disorders in children. However, these can also be attributed to major depression. A cohort study (including 145,702 antidepressant-exposed and approximately 3 million unexposed pregnancies) found no significant increase in risk when confounding factors were controlled for. For example, analysis of antidepressant-exposed siblings (SSRIs, serotonin noradrenaline re-uptake inhibitors, TCAs and bupropion) with unexposed siblings found no increase in risk for any neurodevelopmental disorder (hazard ratio 0.97; 95% CI 0.88-1.06).(9)
Pharmacokinetics in Pregnancy
Physiological changes during pregnancy begin early and fluctuate during the third trimester. These can affect absorption (e.g. hyperemesis) and increase volume of distribution and clearance (liver enzyme induction and increased glomerular filtration rate). These changes result in lower drug concentrations in the blood. Antidepressant doses may need to be increased during pregnancy to maintain efficacy in some people.
Choice of antidepressant is best guided by what is most effective for the individual. Consider remaining with the current antidepressant if it is effective rather than switching, to minimise the risk of relapse. Use the lowest effective dose and avoid polypharmacy. Tapering or stopping antidepressants before birth is not recommended as it may leave the mother without antidepressant cover at a vulnerable time.
|1. The risks of untreated maternal depression outweigh the risks associated with antidepressants.
2. Switching antidepressants is not recommended in pregnant people already established on an effective agent.
3. Also see our bulletin on antidepressants and breastfeeding.