(CNN) — Taking antidepressants while pregnant may be associated with an increased risk of gestational diabetes, a new study suggests.
It turned out that the increased risk appeared to be greatest for the two antidepressant drugs venlafaxine and amitriptyline, according to the study published in the journal BMJ Open on Tuesday. The study suggests a correlation but not causation.
"This study gives another piece of the puzzle showing increased risk of using antidepressants during pregnancy," said Anick Bérard, a professor at the University of Montreal in Canada and director of research on medications and pregnancy at CHU Sainte-Justine Medical Center, who was senior author of the study.
"Depression needs to be treated during pregnancy. There are many forms of treatments -- antidepressants is one of them," she said. "If a woman is pregnant and is taking antidepressants, she should not stop by herself but should have an informed discussion with her treating physician to assess the best way forward."
Gestational diabetes, a type of diabetes that can develop during pregnancy in women, can increase the risk of certain complications for both the mother and baby, including risks of high blood pressure for the expectant mother, needing a cesarean section delivery, having low blood sugar for the baby and developing type 2 diabetes later in life for the baby.
The study involved data on 237,172 pregnancies in Canada. The data, from 1998 to 2015, came from the research tool Quebec Pregnancy Cohort.
Out of those pregnancies, 20,905 included cases of gestational diabetes. Among the pregnancies with a gestational diabetes diagnosis, 1,152 also had been exposed to antidepressants.
After analyzing that data and taking a close look at antidepressant exposure, the researchers found that specifically venlafaxine and amitriptyline were associated with a 27% and 52% increased risk of gestational diabetes.
While the risk was greatest for those two antidepressants, the researchers also found that gestational diabetes risk increased with the longer any antidepressant was taken.
"Short term use was associated with a 15% heightened risk; medium term use was associated with a 17% heightened risk; and long term use with a 29% heightened risk," Bérard said. "The increases remain small but above what we would have expected."
The study had some limitations, including that it is an observational study and more research is needed to determine whether similar findings would emerge among a more diverse group of women, as 88.5% of the pregnancies in the data were among women of a Caucasian background.
More research also is needed to determine why an association between antidepressant use and gestational diabetes exists, but Bérard has some ideas.
"Although biological plausibility is not well understood, we know that antidepressants are associated with weight gain," she said. "Weight gain is associated with insulin resistance and glucose metabolism dysregulation -- all risk factors for diabetes."
Every year up to 10% of pregnancies in the United States are affected by gestational diabetes, according to the US Centers for Disease Control and Prevention.
"Antidepressant use during pregnancy may be a risk factor for gestational diabetes, but we don't know if the strength of the association between antidepressant use and gestational diabetes would be stronger or weaker depending if women were depression-free or if they were still depressed," said Dr. Kristina Deligiannidis, director of Women's Behavioral Health at Northwell Health's Zucker Hillside Hospital and associate professor at the Feinstein Institutes for Medical Research in New York, who was not involved in the new study.
She added that it remains important for women to seek treatment for depression if they are showing signs or symptoms during pregnancy.
"There are many well researched associations of health risks with untreated depression during pregnancy, including functional impairment of the mother, worsening depression, hypertension, preterm labor, higher rates of cesarean delivery, and for the infant, impaired mother-infant bonding, developmental delay and altered brain development, among others," Deligiannidis said.
"Additionally, suicide is the leading cause of direct maternal mortality in the first year postpartum," she said. "The risks of untreated depression must be weighted with what is currently known about the risks of continuing use of antidepressants in pregnancy, and for each woman it should be a patient-focused risk, benefit, alternatives conversation."