Antidepressants used during pregnancy are associated with an increased risk of offspring developing speech or language disorders, scientists have said. The children of women who took the medicine at least twice while expecting were affected in greater proportions by expressive and receptive language disorders as well as some conditions involving articulation of sounds.

Studies looking at the impact of antidepressants taken during pregnancy are not new. Scientists have investigated the link between selective serotonin reuptake inhibitors (SSRIs) – drugs which are commonly given to treat depression – and the risk of babies developing a range of conditions, from congenital birth defects to autism spectrum disorders.

However, this new research, published in JAMA Psychiatry, is the first to assess the risk of developing a speech or language disorder.

SSRIs can be life-saving drugs for women who suffer from depression or other psychiatric disorders, and most of the time studies only reveal a small risk increase, even if their conclusions are alarmists. But because they can permeate the placenta and enter the fetal circulation, scientists believe it is important to understand what the effects of these drugs are.

Large-scale study

Here, the team from Columbia University looked at a very large sample of 845,345 single, live births between 1996 and 2010 taken from national registries in Finland. Within this cohort, they examined different groups – 15,596 mothers who purchased SSRIs once or more before or during pregnancy, 9,537 diagnosed with a psychiatric disorder one year before or during pregnancy but did not buy antidepressants and 31,207 mothers who neither purchased antidepressants nor were given depression-related diagnoses. The scientists also examined the babies' health data.

They found that the women who had took SSRIs at least twice during pregnancy had a 37% increased risk of speech and/or language disorders among their offspring compared to those not treated with antidepressants.

These findings are robust, but the researchers say factors other than SSRIs use may explain the development of these disorders. These women may have other risk factors as a result of their mental health issues, such as a poorer diet, and they are more likely to be obese, to drink and take drugs. All of this can also have a negative impact on the baby to come.

"The strengths of our study include the large, population based birth cohort, prospective data on SSRI purchases during pregnancy, a comparison group of mothers with depression who were not taking antidepressants, and an extensive national register database that included other known confounders. However the severity of maternal depression cannot be ruled out as an explanation for the increased childhood speech and language disorders among mothers who filled more than one SSRI prescription, and further study is warranted", concluded Alan Brown, the lead author of the research.