Using a standard dose of antidepressants during pregnancy appears to be safe for the baby, according to new research from the University of Oslo and Akershus University Hospital. However, persistently high doses may be linked to changes in the placenta and an increased risk that the newborn will require intensive care.
The decision of whether to continue antidepressant medication during pregnancy is often difficult for women, weighing the risks of untreated severe depression against potential risks to the developing baby. As Professor Soili Marianne Lehto, from the University of Oslo (UiO) and Akershus University Hospital (Ahus), explains, “We know that untreated severe mental illness can be dangerous for both the baby and the mother. Lack of appropriate treatment can increase the risk of relapse, suicidal thoughts, poor engagement with antenatal care and complications in pregnancy. For many, this choice feels like an ethical and medical dilemma when it comes to antidepressant medications.”
Standard Doses Appear Safe During Pregnancy
The new study examined antidepressant use during pregnancy and related perinatal outcomes. The results suggest that using antidepressants at standard doses appears to be safe, based on the factors assessed after birth. “Using a standard dose does not seem to be harmful to the baby based on the factors we have assessed after birth,” says senior researcher Guro Pauck Bernhardsen at Akershus University Hospital.
Researchers evaluated several outcomes, including birth weight, placental weight, umbilical cord length, preterm birth, Apgar scores (a rapid assessment of newborn health), and whether the newborn required admission to the neonatal intensive care unit (NICU).
High, Long-Term Doses Linked to Increased Risk
The study emphasizes the importance of dosage. “We see that persistently high doses of antidepressants are associated with changes in the placenta. Sustained high doses are also linked to an increased risk that the baby will need treatment in a neonatal intensive care unit,” Bernhardsen notes.
For women with severe mental illness who are concerned about continuing medication during pregnancy, these findings offer some reassurance. “Our findings support the view that use of standard-dose SSRIs during pregnancy may be safe. However, persistently high doses may carry extra risk. These women should be closely followed up by a doctor during pregnancy,” Bernhardsen advises.
The Study: SSRIs, Dose, Duration, and Patterns of Use
The research focused on selective serotonin reuptake inhibitors (SSRIs), a common class of antidepressants used to treat depression and anxiety. “SSRIs are the most commonly used antidepressants in the Nordic countries, including among pregnant women,” explains Bernhardsen.
Unlike many previous studies that simply categorized antidepressant use as “yes” or “no,” this study considered dose, duration, and patterns of use throughout pregnancy. The team analyzed registry data from Kuopio University Hospital in Finland, comparing 553 mothers who used antidepressants during pregnancy with 2,765 mothers who did not. The groups were matched based on depression, other psychiatric diagnoses, and age to ensure comparability.
Women who used antidepressants were categorized into four groups based on their medication patterns: 1) standard dose throughout pregnancy, 2) low dose that increased during pregnancy, 3) high dose throughout pregnancy, and 4) tapering from a standard dose early in pregnancy down to a lower dose later. Researchers then examined outcomes for both mothers and babies.
Why Placental Health Matters
For mothers who took high doses of antidepressants throughout pregnancy, the researchers observed several notable results. Placental weight is known to correlate with infant birth weight; a relatively large placenta compared to the baby can indicate reduced effectiveness in delivering nutrients. In this study, women taking high doses had larger placentas and a higher placenta-to-birthweight ratio.
“Measuring placental size relative to the baby’s weight can provide important information about whether the baby achieved optimal growth in utero. Poor growth can indicate a need for extra follow-up after birth and may have implications for long-term health,” Bernhardsen explains.
Infants exposed to high doses of antidepressants had roughly double the risk of NICU admission compared to infants of women who did not use antidepressants during pregnancy.
Balancing Medication Changes Against Mental Health Risks
In Norway, just under 2% of pregnant women use SSRIs. “The lower proportion of SSRI use among pregnant women compared with non-pregnant women may indicate that many choose to stop treatment for depression during pregnancy. This is likely due to uncertainty about possible consequences for the fetus,” Lehto says.
She stresses the importance of individualized evaluation of antidepressant dosage in pregnant women. Newborns of women on high doses should be closely monitored after birth. “The risks of changing or reducing treatment should always be taken into account when making decisions on antidepressant dosage in pregnant women,” Lehto emphasizes.
