Women taking antipsychotic medications have a “much higher” likelihood than other women of experiencing many different types of adverse events during pregnancy, according to a study in the British Medical Journal. However, after the researchers applied a “high dimensional propensity score” (HDPS) algorithm to their data, many of those differences disappeared and news media subsequently reported that antipsychotics are “safe” during pregnancy.
The researchers from Women’s College Hospital in Toronto examined data from several large health databases in Ontario, Canada, and searched for a number of possible adverse effects among pregnant women who’d taken antipsychotics between 2003-12. “The maternal and perinatal medical risks associated with antipsychotic drug use itself during pregnancy appear to be minimal,” said lead author Simone Vigod in a press release. Vigod described the findings to The Globe and Mail as “reassuring.”
In the study itself, the researchers wrote that, “Antipsychotic drug use in pregnancy did not substantially worsen maternal medical or short term perinatal outcomes in a cohort of women closely matched on baseline characteristics using a HDPS algorithm. The only exceptions were a slightly higher risk of labour induction and vaginal delivery among exposed pregnancies.”
They then added: “However, antipsychotic users had outcome event rates that were much higher than in the general population. This was true for the main maternal outcomes of the hypertensive disorders of pregnancy and venous thromboembolism, and for the main perinatal outcomes, including almost a 14% rate of preterm birth, about twice that in the general population. Although there were few events, the observed neonatal mortality rate of 1% was twice that of the general population.”
The researchers suggested that there must have been some other “factors” at work — other than antipsychotics — making antipsychotic users have consistently worse outcomes on every measure. The researchers did not suggest what those other “factors” might be. But in their use of the “high dimensional propensity score” algorithm, the authors explained that they tried to more closely match the antipsychotic users and controls, such as by trying to ensure that they matched for use of other psychotropics, and for pre-pregnancy use of psychotropics. The authors acknowledged that this may have affected their results since other psychotropics are believed to also have negative effects on pregnant women.
The study did not look specifically at possible negative short or long-term impacts on infants.
Vigod, Simone N., Tara Gomes, Andrew S. Wilton, Valerie H. Taylor, and Joel G. Ray. “Antipsychotic Drug Use in Pregnancy: High Dimensional, Propensity Matched, Population Based Cohort Study.” BMJ 350 (May 13, 2015): h2298. doi:10.1136/bmj.h2298. (Full text)
Antipsychotic drug use in pregnant women appears to pose minimal risk, new study suggests (Women’s College Hospital press release on MedicalXPress, May 13, 2015)
Antipsychotics shown safe for pregnant women and their babies (The Globe and Mail, May 13, 2015)