Newborns whose mothers use antidepressant medication during the late stages of pregnancy may be at greater risk of persistent pulmonary hypertension, according to a new study published in JAMA.

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Researchers say the use of SSRIs and non-SSRI antidepressants in the final 90 days of pregnancy may raise the risk of PPHN.

Persistent pulmonary hypertension of the newborn (PPHN), or neonatal pulmonary hypertension, occurs when a baby's blood circulation does not allow them to breath properly outside of the womb.

In PPHN, a newborn experiences high blood pressure in the arteries that travel to the lungs, restricting the amount of blood that flows to them. As such, the amount of oxygen in the bloodstream is reduced.

PPHN is a life-threatening condition. It is estimated that around 10-20% of infants born with the condition do not survive, while many of those who do survive suffer severe lifelong illnesses, such as chronic lung disease and neurodevelopmental disorders.

In 2006, the US Food and Drug Administration (FDA) issued a public health advisory for the use of the antidepressants selective serotonin reuptake inhibitors (SSRIs) during late pregnancy, after one study suggested such use increases the risk of PPHN.

However, in 2011, the FDA updated their public health advisory on SSRI use in late pregnancy, stating that health care professionals should not alter their current treatment strategies for depression during pregnancy because further studies evaluating the link between SSRI use in late pregnancy and PPHN have produced "conflicting findings."

But according to the researchers of this latest study, including Krista F. Huybrechts of Brigham and Women's Hospital in Boston, MA, previous research that found no increased risk of PPHN with SSRI use in late pregnancy were small, and therefore, may have had "insufficient power" to detect an increased risk.

PPHN risk highest with SSRI use in final 90 days of pregnancy

As such, Huybrechts and colleagues set out to assess the link between the use of both SSRIs and non-SSRI antidepressants and risk of PPHN using a sample of 3,789,330 pregnant women from 46 US states and Washington, DC.

All women were enrolled in the 2000-10 Medicaid Analytic eXtract (MAX). SSRI and non-SSRI use among the pregnant women was assessed from 90 days before they gave birth up until delivery. PPHN incidence among newborns was assessed in the 30 days after delivery.

The team identified antidepressant use among 128,950 (3.4%) of the women in the final 90 days of pregnancy, with 102,179 (2.7%) of these using SSRIs and 26.771 (0.7%) using non-SSRIs.

Compared with women who did not use antidepressants in the late stages of pregnancy, those who used antidepressants were more likely to have newborns with PPHN. Incidence of PPHN was 20.8 per 10,000 infants not exposed to antidepressants and 31 per 10,000 infants exposed to antidepressants.

PPHN incidence was slightly higher among infants exposed to SSRIs, at 31.5 per 10,000, compared with 29.1 per 10,000 among infants exposed to non-SSRIs.

The researchers note that the risk of PPHN with both SSRI and non-SSRI use reduced when potential confounding factors were accounted for.

Their findings, the team says, highlight a small, increased risk of PPHN with the use of antidepressants in late pregnancy, particularly SSRIs. They note that the identified risk increase is "more modest" than that reported in previous studies.

The researchers add:

"Clinicians and patients need to balance the potential small increase in the risk of PPHN, along with other risks that have been attributed to SSRI use during pregnancy, with the benefits attributable to these drugs in improving maternal health and well-being."

Previous studies have highlighted other potential health risks of antidepressant use during pregnancy. In April 2014, for example, a study published in the journal Pediatrics linked maternal SSRI use to increased risk of autism in male offspring.