Women who take antipsychotic drugs during pregnancy are more likely to develop gestational diabetes, say researchers.

The study, conducted by Robert Bodén. M.D., Ph.D., of the Centre for Pharmacoepidemiology, Karolinska Institutet, Stockholm, and Uppsala University, Uppsala, Sweden, and colleagues, is published in Archives of General Psychiatry.

Antipsychotic drugs are used to treat severe mental illnesses such as schizophrenia and bipolar disorder, “however, the evidence concerning use of antipsychotics during pregnancy is generally lacking or weak,” say the researchers.

For the study, the team examined medical records of Swedish women who gave birth in Sweden between July 2005 and December 2009. Of the women examined, 357,696 had no prescriptions for antipsychotics, 169 women were prescribed the antipsychotics olanzapine and/or clozapine, and 338 were prescribed other antipsychotics.

The researchers said:

“Gestational diabetes was more than twice as common in mothers who used antipsychotics (seven mothers [4.1 percent] for those prescribed olanzapine and/or clozapine and 15 [4.4 percent] for those prescribed other antipsychotics) than in the total population of pregnant women (5,970 [1.7 percent]).”

Although the team found that women were more likely to give birth to a small for gestational age (SGA) infant if they were using antipsychotics, the risk was no longer statistically significant after adjusting for maternal factors.

The researchers explained:

“In conclusion, maternal use of antipsychotics during pregnancy, regardless of the drug group, is associated with an increased risk of gestational diabetes. The increased risk of giving birth to an SGA infant observed among women treated with antipsychotics during pregnancy is probably an effect of the confounding factors, such as smoking.”

In addition, results showed that exposure to olanzapine and/or clozapine did not increased the risks of being large for gestational age (LGA) for birth weight or birth length. However, the risks did increase for head circumference.

The researchers conclude: “Pregnant women treated with antipsychotics should be closely monitored for gestational diabetes and deviating fetal growth.”

Written by Grace Rattue