New research has found that prenatal exposure to the class of antidepressants called selective serotonin reuptake inhibitors (SSRIs) is associated with lower birth weight and gestational length.
Investigators discovered infants exposed to SSRIs during two or more trimesters weighed 205 grams or about half a pound less than infants whose mothers were not exposed to any antidepressants.
The study, published in the International Journal of Epidemiology also found that the infants would also be born 4.9 days earlier, on average.
However, study co-author Dr. Katerina Nezvalova-Henriksen commented that, “the biological mechanisms by which long term SSRIs exposure may affect birth weight remain unknown.”
“Severe depression or depression not responding to non-pharmacological therapy may negatively affect the course of pregnancy and the pre- and postpartum period,” she said. “The risks and benefits of SSRI therapy should therefore be carefully evaluated in each individual case.”
Researchers from Norway and Canada used data from the Norwegian Mother and Child Cohort Study (MoBa) and the Medical Birth Registry of Norway to perform the study. They measured the effect of SSRIs and maternal depression on birth weight and gestational length, using a sibling design method.
This methodology helps to differentiate the current study from previous studies looking into prenatal SSRI effects.
Investigators assessed 27,756 siblings in the study, 194 of which were prenatally exposed to SSRIs. By applying the sibling design, the researchers were able to address the unmeasurable and unknown family-level differences that may have been a source of bias.
The study was divided into a group where women used SSRIs during pregnancy and a group that did not use any antidepressants.
The reasons for women taking SSRIs included not only depression and anxiety but also other neuropsychiatric disorders. In the database, 7,450 mothers had a lifetime history of major depression.
The study concluded that neither shared genetics nor family environment can explain the associations between exposure to SSRIs and birth weight. Therefore, a relationship between material use of SSRIs and lower birth weight and earlier deliveries should be continued to be explored.