Depression affects an estimated 13% of pregnant women and new mothers.
Pregnancy complications for which the risk was reduced included preterm birth and Cesarean section.
"To our knowledge, the association between taking antidepressants in pregnancy and a lower risk of preterm birth is a novel finding," says senior author Dr. Alan Brown, professor of psychiatry and epidemiology at Columbia University Medical Center in New York, NY.
"Up to now, studies which were based on maternal underlying psychiatric illness had small sample sizes and reported inconsistent results," he adds.
The study, published in the American Journal of Psychiatry, aimed to assess the relationship between the use of selective serotonin reuptake inhibitors (SSRIs) during pregnancy and pregnancy complications.
Depression is a serious mental illness that is a frequent problem both during and after pregnancy. According to the Office on Women's Health, around 13% of pregnant women and new mothers have depression.
SSRIs are the most commonly prescribed form of antidepressant medication and work by preventing the reabsorption of the neurotransmitter serotonin in the brain. Doing this appears to improve communication between brain cells that, in turn, improves mood.
Previous research suggests that mental illness such as depression could influence fetal health outcomes, and maternal depression has been identified as a possible risk factor for low birthweight and premature birth.
To assess the impact of SSRIs, the researchers analyzed the outcomes of 845,345 single births recorded in the Finnish Medical Birth Register from 1996 through to 2010. They also obtained relevant data on maternal psychiatric history, medical history and prescription drug purchases.
Reduced risk of preterm birth, increased risk of neonatal problems
Pregnancies were separated into three categories: exposed to SSRIs (15,729 births), unexposed to SSRIs but with psychiatric diagnoses (9,652 births) and unexposed to SSRIs and psychiatric diagnoses (31,394 births). The pregnancy outcomes for these three groups were then compared.
Among mothers with psychiatric diagnoses, the researchers found that the risk of preterm birth was 16% lower among women using SSRIs compared with those that did not. More significantly, the risk of very preterm birth was nearly 50% lower among women using the medication than those that did not.
Women who had been diagnosed with psychiatric disorders who did not take SSRIs were also more likely to require a Cesarean section than those without a diagnosis or taking SSRIs, with a 26.5% risk compared with a 17% risk.
However, the researchers also found that SSRI use was associated with an increased risk of all neonatal problems - problems affecting a baby at birth - that led to longer stays in hospital and required more medical attention. These problems included issues with breathing.
Dr. Brown believes the study points toward more individualized care for women with psychiatric diagnoses:
"Given these divergent findings, the decision whether to prescribe these medications during pregnancy should be individualized to the mother's medical and psychiatric history."
This study is not the first to find an association between SSRIs and neonatal problems. Last month, Medical News Today reported on a study published in The BMJ that found there may be a link between maternal use of SSRIs and a greater risk of birth defects.
In the study, women prescribed SSRIs during the stages of early pregnancy were more likely to give birth to infants with heart problems and with abnormal brain and skull formation than women who did not take antidepressant medication.