Antipsychotic use in pregnancy should be closely monitored

By Sarah Guy

Use of any type of antipsychotic during pregnancy increases the risk for women developing gestational diabetes, show Swedish study results that also indicate a link between antipsychotics and a risk for giving birth to a small for gestational age (SGA) infant.

However, this latter finding is likely to be an effect of confounding factors, such as smoking, say the researchers.

The team also reports that use of the more recent antipsychotics - olanzapine and/or clozapine - during pregnancy is associated with giving birth to infants with large for gestational age (LGA) head circumference - an association that could not be explained by the current study results, and which warrants future investigation.

"Pregnant women treated with antipsychotics should be closely monitored for gestational diabetes and deviating fetal growth," recommend Robert Bodén (Uppsala University) and co-researchers.

Using data from three Swedish national health registers, the team investigated gestational diabetes incidence and fetal growth in 169 women who took olanzapine or clozapine during pregnancy (group 1), 338 women who took any other type of antipsychotic (group 2), and 357,696 women in the general population who did not take any antipsychotic drugs (group 3).

Rates of gestational diabetes were more than double among mothers who used antipsychotics than those in the general population, at 4.1% and 4.4% versus 1.7% in groups 1, 2, and 3, respectively, report the researchers.

These differences remained significant after adjusting results for variables including birth order, maternal age, cohabitation, and smoking; however, they lost significance after early pregnancy body mass index was included in the analysis.

Group 1 and 2 infants were more than twice as likely as those born to mothers in the general population to be SGA - defined as the 2.3rd percentile or less - with odds ratios (ORs) of 2.63 and 2.02, respectively. Group 2 antipsychotics were also associated with a twofold increased odds for SGA birth length and head circumference, with respective ORs of 2.17 and 2.07.

Furthermore, group 1 infants had more than double the risk for a LGA (97.7th percentile or greater) head circumference compared with general population infants, at an OR of 2.79.

While adjustment for maternal factors including smoking attenuated the SGA risks, group 1 infants' chances of LGA head circumference increased, with an OR of 3.02, write Bodén et al in the Archives of General Psychiatry.

The results indicate the opposite effect of previous study results that link gestational diabetes to LGA offspring, which could be a result of a more "direct pharmacological insulin resistance-promoting effect by the antipsychotics," they conclude.

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