LAS VEGAS – Assessing the risk of major congenital malformations related to antipsychotic exposure requires detailed assessment of other sources of risk, including those related to the diagnosis and associated behaviors, according to Jonathan M. Meyer, MD.
Doug Brunk/MDedge News
Dr. Jonathan M. Meyer
However, the largest study to date showed no significant difference in rates of major congenital malformations for those with one or more prescriptions for atypical antipsychotics in the first trimester, compared with pregnancies with no first trimester antipsychotic exposure.
In the U.S. general population, the estimated risk of major birth defects is 2%-4%, Dr. Meyer, a clinical professor of psychiatry at the University of California, San Diego, said at an annual psychopharmacology update held by the Nevada Psychiatric Association.
Medications represent one source of risk for major congenital malformations in patients with psychiatric illness. Other factors include lifestyle factors such substance abuse and smoking, diet and physical activity, adherence with medical/prenatal care regimens, general medical disease burden, and unknown genetic risk because of the illness itself.
Until recently, published studies examining antipsychotic exposure and the risk for congenital malformations have been flawed because of numerous factors, Dr. Meyer said, including the small sample size of live births, absence of systematic collection of risk data prior to and during pregnancy, and failure to examine all possible covariates that might moderate the risk potentially attributable to the medication itself.
For example, researchers led by Frank Habermann, PhD, prospectively evaluated three cohorts who were followed in a psychiatry consultation in Freiburg, Germany: 453 women who received atypical antipsychotics in the first trimester of pregnancy (group A); 238 women who received typical antipsychotics in the first trimester of pregnancy (group B); and 1,104 women who had no records of treatment with medications associated with harmful fetal effects (group C).
Covariates included maternal age, alcohol consumption, smoking habits, number of previous spontaneous abortions, number of previous malformed children, and gestational week at delivery (J Clin Psychopharmacol. 2013;33[4]:453-62).
The researchers found that 5.2% of women in group A gave birth to a child with a major congenital malformation, compared with 5% in group B and 2.5% in group C. Nonsignificant associations were observed between group A vs. B (adjusted odds ratio, 1.26; 95% confidence interval, 0.57-2.82) and group B vs. C (adjusted OR, 1.71; 95% CI, 0.78-3.76). The only significant association noted was between group A and C (adjusted OR, 2.17; 95% CI, 1.20-3.91). However, Dr. Meyer emphasized limitations of the study, including its small sample size and certain missing covariates, including illegal substance use.