Higher doses of common fertility drug linked to pregnancy risks
About 1 in 6 people experience infertility, with irregular or absent ovulation among the most common causes. The drug clomiphene citrate has long been a mainstay of fertility treatment, but a growing body of University of Adelaide research is raising safety concerns about higher cumulative doses.
A new study published in BMJ Open reveals a potential link between higher doses of the common fertility drug clomiphene citrate and increased risks during pregnancy. Researchers from the University of Adelaide, in collaboration with Boston University and the Centers for Disease Control and Prevention, analyzed data from 21,004 in vitro fertilization (IVF) embryo transfer cycles in the United States.
The findings suggest that women receiving cumulative doses of 500-749 milligrams of clomiphene citrate had a 12% higher risk of miscarriage, while those receiving doses of 750-999 mg faced a 38% higher miscarriage risk. Women who received 750 mg or more were more than twice as likely to have twins or other multiple births. While the study suggests a dose-dependent increase in pregnancy losses, the association with stillbirth was not statistically significant due to the rarity of the higher doses.
The research indicates that higher cumulative doses of clomiphene citrate do not improve the likelihood of a live birth but do increase the chances of multiple births, which can lead to adverse outcomes for both mother and child. Lead author Associate Professor Sheree Boulet emphasized the clear dose-response relationship observed, noting that increasing the dose did not significantly enhance the chances of a successful pregnancy.
The study builds on previous research from the University of Adelaide linking clomiphene citrate to higher risks of pregnancy loss, stillbirth, perinatal death, and certain birth defects. Senior researcher Professor Michael Davies highlighted the need for further studies to better understand the dose-response relationship and explore personalized dosing strategies to improve safety.
Until more robust evidence is available, clinicians are advised to adhere to manufacturers' safety recommendations and avoid unnecessarily increasing cumulative doses.
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