(ORLANDO, Dec. 6, 2025) A groundbreaking study has revealed that the sickle cell medication hydroxyurea, when taken during or shortly before pregnancy, does not appear to cause specific issues in newborns. This marks the first prospective study to examine pregnancies involving hydroxyurea exposure, providing significant reassurance for women who rely on the drug to manage sickle cell complications.
Despite the positive findings, the study’s authors recommend discontinuing hydroxyurea before pregnancy whenever possible, due to potential undocumented effects. However, the research offers crucial insights for cases where unplanned pregnancies occur or when hydroxyurea remains the most viable treatment option. Alternatives like blood transfusions are not universally available or safe for all patients.
Study Insights and Expert Opinions
The study, led by Dr. Anoosha Habibi, associate professor at the Hôpitaux Universitaires Henri Mondor in Créteil, France, highlights improved live birth rates compared to previous research, with no maternal mortality reported. Dr. Habibi emphasizes a pragmatic approach, stating, “We have to decide case by case and evaluate the risk from transfusion and stopping hydroxyurea.”
“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,” said Dr. Habibi.
Hydroxyurea is an oral medication that helps maintain the healthy shape of blood cells, preventing complications like painful vaso-occlusive crises. Historically, women have been advised to cease taking the drug three to six months prior to conception due to unknown effects during pregnancy.
Challenges and Regional Disparities
Dr. Habibi points out the challenges faced by women needing to stop hydroxyurea, as many are highly symptomatic and cannot predict when pregnancy will occur. “Many women remain without treatment for months, during which some develop severe vaso-occlusive crises and complications,” she noted.
In regions with limited resources, such as parts of Africa, India, and the Caribbean, the safety and availability of transfusions are restricted. In these areas, discontinuing hydroxyurea could increase the risk of crises, worsening outcomes for both mother and child.
“In higher-resourced settings, we can manage treatment interruption and provide safe transfusions for most patients, but in many regions… the safety of transfusion is limited, or the access is simply unavailable,” Dr. Habibi explained.
Research Methodology and Findings
The study analyzed data from 245 pregnancies involving 183 women across 77 medical centers in Europe between 2009 and 2025. Most participants had been on hydroxyurea long-term before conceiving, with 84% taking it at the time of conception, indicating many pregnancies were unplanned.
Outcomes from 178 pregnancies were examined, excluding those voluntarily aborted or ongoing at the time of analysis. Three-quarters resulted in live births, with no maternal deaths or hydroxyurea-related newborn malformations reported.
The miscarriage rate was 17%, similar to the general population, and premature births also accounted for 17%, aligning with previous sickle cell studies.
Two pregnancies were terminated for maternal medical reasons, and two fetal deaths occurred, neither linked to hydroxyurea exposure. These findings suggest that continuing hydroxyurea during pregnancy could be justified when transfusion is not an option.
Future Research and Implications
While the study provides valuable insights, researchers acknowledge its limitations, as it was not designed to monitor pregnancies comprehensively. Dr. Habibi calls for further studies to confirm these findings and assess the long-term outcomes for children exposed to hydroxyurea in utero.
The study was commissioned by the European Medicines Agency and funded by AddMedica. Dr. Habibi is scheduled to present the findings at the Orange County Convention Center on December 7, 2025.
As the medical community continues to explore safe treatment options for pregnant women with sickle cell disease, this study represents a significant step forward, potentially influencing future guidelines and patient care strategies.
