‘Reassuring’ findings on antidepressants and miscarriage can help GPs explain risk
A large UK study has found no evidence suggesting that taking antidepressants before pregnancy and into the first trimester increases the risk of miscarriage.
But analysis of data from more than a million pregnancies in UK GP records showed a small, clinically insignificant increased risk of miscarriage associated with starting antidepressant use in the first three months of pregnancy.
When adjusted for factors that may impact the results, the risk of miscarriage was found to be 13.1% in the women not prescribed antidepressants in the first trimester and 13.6% in those prescribed the drugs.
There was no difference in risk when looking at those prescribed antidepressants across the three months before pregnancy and into the first trimester compared with those not exposed to the drugs.
Reporting the results in the British Journal of General Practice, the researchers from the University of Bristol said antidepressant use during pregnancy is rising and evidence on risk of miscarriage is conflicting.
The figures reported from this large dataset can help GPs counsel women on the risks for women planning pregnancy or becoming pregnant while taking antidepressants, they concluded.
It is not possible to say whether the small increased risk is causal or not due to limitations with the data but the figures will provide a ‘useful clinical decision-making aid’, they said.
The possibility for reverse causation may explain some of the miscarriages seen in the treatment group, where antidepressants were sought following a miscarriage.
It could also be the case that those seeking healthcare for depression, anxiety, or other indications treated with antidepressants may be more likely to report pregnancies and early losses, the researchers noted.
In the cohort, which spanned pregnancies from 1996 to 2018, just over 7% of women were prescribed antidepressants in early pregnancy.
Given these limitations it ‘reassuring’ the modest increase in absolute risk would translate to a number needed to harm of 200 if causal, they added.
A large Danish study published a decade ago had found an association between antidepressant use during pregnancy and miscarriage in the first trimester of a similar magnitude.
But they concluded that confounding by lifestyle factors explained the link because it disappeared when compared with individuals with unmedicated depression during pregnancy.
‘The findings are reassuring for prescribing clinicians and individuals concerned about antidepressant use during early pregnancy and miscarriage, providing both parties with robust supportive evidence for informed decision making in clinic,’ they said.
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