Do pregnant women benefit from taking antidepressants?

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Publication Date: 
Wed, 2009-09-30

By Jane Shulman

Pregnant North American women are taking anti-depressants more than ever. The medical community has long advised women to avoid pharmaceuticals during pregnancy, but there is a growing trend to encourage women taking anti-depressants to keep taking them when they become pregnant, and to prescribe the drugs to pregnant women with depressive symptoms. The assumption being made with these prescriptions is that the potential risks to women and fetuses from taking anti-depressants outweigh the potential risks of letting depression go untreated. But is there really evidence of that these drugs benefit pregnant women, and does that benefit outweigh the potential risk?

During a popular Canadian Women’s Health Network webinar last October, Dr. Barbara Mintzes discussed the history of prescription drugs during pregnancy and the current debate. Mintzes is an Assistant Professor at University of British Columbia’s Department of Pharmacology & Therapeutics, member of the UBC Centre for Health Services & Policy Research, and a Steering Committee member of Women and Health Protection. She and colleagues are aware of the conflicting information about the safety and benefits of taking selective serotonin reuptake inhibitor (SSRI/SNRI) class anti-depressants (such as Prozac, Paxil and Effexor) during pregnancy.

What is known is that anti-depressants are being prescribed to pregnant women ‘off-label,’ meaning prescribed for a use for which they were not approved.  Mintzes explains that “Anti-depressants are unapproved for use in pregnancy in Canada, or actually in any other country.” While it is illegal for drug companies to promote their products for ‘off-label’ use, doctors can prescribe any drug for any use once it is on the market.

There is a generally recognized need for caution when using medications during pregnancy that has come out of two disasters – Thalidomide and Diethylsilbestrol (DES), drugs that had devastating effects on babies born to women who took them while pregnant. In the case of Thalidomide, some babies had severe birth defects. DES caused higher rates of cancer and reproductive problems in adult women who were exposed while their mothers were pregnant with them. DES sons also have higher rates of abnormalities of the reproductive organs. Additionally, women who took DES while pregnant have higher rates of breast cancer.

These disasters, Mintzes notes, brought attention to the possibility of unpredictable and long-term harm from drug use in pregnancy. With that in mind, and with the conflicting advice women were receiving about using SSRIs while pregnant, Mintzes and colleagues decided to wade through the studies that had been done to see if there was in fact evidence of benefit to taking these drugs for women and their babies.

Any time a medicine is used, there is a need to weigh the potential benefit against the potential harm. This is why medicines have to be tested systematically before they’re approved for use. With ‘off-label’ use – as is the case with antidepressants in pregnancy - the company marketing the drug has not had to show scientific evidence to the government of a specific benefit for this use. That evidence may or may not exist. Since all medicines can cause harm as well as benefit, unless there is rigorous scientific evidence that benefit is likely to outweigh harm, a medicine should not be taken.

Mintzes worked with Patricia Fortin, a research consultant at UBC’s drug assessment group Therapeutics Initiative, Jon Jureidini, an Associate Professor at the University of Adelaide’s Department of Psychiatry and UBC Pediatrics professor Tim Oberlander. Funded mainly by Health Canada’s Bureau of Women’s Health and Gender Analysis, they carried out a systematic search for all studies comparing women with depression who did or did not take antidepressants during pregnancy, and evaluated the study results.

Their conclusion? Even after searching for all published and unpublished studies – worldwide – and despite the many claims made in favour of antidepressant use, they failed to find any scientific evidence that either pregnant women or their babies benefit from use of SSRI/SNRI antidepressants.

Mintzes’ team found eight studies of women who were pregnant and diagnosed with depression. In all cases, the studies compared the outcomes for mothers and babies of those taking antidepressants and those who had no treatment of any kind. There were no studies, Mintzes notes, comparing pregnant women who took SSRI/SNRIs with those who were treated in other ways, such as cognitive-behavioural therapy or regular exercise.

The size and quality of the eight studies varied, as did the degree of depression of the women who participated. All were observational, meaning that although there was a control group, women who chose to take antidepressants were compared with others who did not. Interpreting the results was complicated by differences between the women who took antidepressants and those who did not. For example, some had a longer history of depression or more severe depression.

Five of the eight studies were also quite small, with weaker research methods, and in those cases, Mintzes notes it was hard to say why there were so many poor birth outcomes. Was it the exposure to the drug, or was it because of differences between the women who were and were not taking antidepressants? Were issues like poverty, known to be a factor in depression and birth outcome, taken into account? The three larger – and more scientifically solid - studies they reviewed followed large populations of women, including one that included all women in British Columbia who gave birth between 1998 and 2001. 

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