(ORLANDO, Dec. 6, 2025) A groundbreaking study has found that the sickle cell medication hydroxyurea does not appear to cause specific issues in newborns when taken during or shortly before pregnancy. This is the first prospective study of its kind, offering new insights into the management of sickle cell disease in pregnant women.
The research, however, still advises discontinuing the drug before pregnancy when possible, due to potential undocumented effects. Despite this caution, the findings provide reassurance for women facing unplanned pregnancies or those for whom hydroxyurea is the best option to manage sickle cell complications. Alternatives like blood transfusions are not universally available or safe for all patients.
Expert Insights and Study Details
“Overall, the rate of live births was better than that seen in previous studies, and we had no maternal mortality, even though these patients were highly symptomatic,” stated Dr. Anoosha Habibi, the study’s lead author and associate professor at the Hôpitaux Universitaires Henri Mondor in Créteil, France. “Based on these findings, we call for a pragmatic approach. We have to decide case by case and evaluate the risk from transfusion and stopping hydroxyurea.”
Hydroxyurea is an oral medication that maintains healthy blood cell shape, preventing complications like painful vaso-occlusive crises and tissue damage in sickle cell patients. Traditionally, women are advised to stop taking the drug three to six months before conception due to unknown effects during pregnancy.
“Women are usually advised to stop hydroxyurea several months before pregnancy, but this is extremely difficult because these patients are often highly symptomatic and no one knows exactly when pregnancy will occur,” said Dr. Habibi.
Challenges in Low-Resource Settings
Dr. Habibi highlighted the challenges faced in low-resource settings, where treatment interruption and safe transfusions are not always feasible. “In higher-resourced settings, we can manage treatment interruption and provide safe transfusions for most patients, but in many regions in Africa, India, and the Caribbean, the safety of transfusion is limited, or the access is simply unavailable,” she explained. “In those contexts, asking women to stop hydroxyurea may actually put them in danger of vaso-occlusive crises, and both maternal and fetal outcomes can worsen.”
Drawing from a collection of prospective cohort studies across 77 medical centers in Europe, the research included data from 245 pregnancies involving 183 women taking hydroxyurea between 2009 and 2025. In 84% of these cases, women were on hydroxyurea at conception, indicating many pregnancies were unplanned.
Study Findings and Implications
The study analyzed 178 pregnancies, excluding those voluntarily aborted or ongoing, and those where hydroxyurea was discontinued before conception. Three-quarters of these pregnancies resulted in live births, with no maternal deaths or hydroxyurea-related newborn malformations reported.
The miscarriage rate (17%) was similar to that of the general population, and the premature birth rate (17%) mirrored previous studies of individuals with sickle cell disease.
Two pregnancies were discontinued for maternal medical reasons, and two fetal deaths occurred, neither attributed to hydroxyurea exposure. These findings suggest that continuing hydroxyurea during pregnancy could be a viable option when transfusion is not possible, especially for women at high risk of untreated sickle cell complications.
Future Research and Presentation
While the data were collected prospectively, the study was not specifically designed to monitor pregnancies, leading to limitations in pregnancy outcome data and transfusion statistics. Dr. Habibi emphasized the need for further studies to confirm these findings and assess long-term outcomes for children exposed to hydroxyurea in utero.
The study was commissioned by the European Medicines Agency and funded by AddMedica. Dr. Anoosha Habibi is set to present these findings on Sunday, December 7, 2025, at 2:25 p.m. Eastern time during the plenary scientific session at the Orange County Convention Center.
