The SAFE study is a long-term research project that watches people with sickle cell anemia (SCA) over time. The main goal is to see how a medicine called hydroxyurea affects their growth, puberty, and ability to have children. A second goal is to see how hydroxyurea affects pregnancy outcomes, by comparing people who take the medicine to those who don't.

Hydroxyurea is a medicine that helps people with sickle cell anemia (SCA), a serious blood disease. It works by increasing a special type of hemoglobin (called fetal hemoglobin) that helps prevent sickle cell problems.

This medicine is especially helpful in places where it's hard to get safe blood transfusions. Studies from around the world have shown that hydroxyurea is safe and can reduce serious health problems caused by SCA (like pain, strokes, and lung issues). It can also help people with SCA live longer, healthier lives.

However, the investigators still don't know everything about how hydroxyurea affects long-term growth, puberty, fertility, or pregnancy; especially in areas with fewer medical resources.

To learn more, researchers are planning a large international study. They will follow people with SCA over time to see how hydroxyurea affects their development, ability to have children, and pregnancy outcomes. Participants will visit the clinic every few months for check-ups, blood tests, and other health assessments. Girls who have started their periods will take pregnancy tests every six months, and boys may be asked to provide a semen sample if they agree. Everyone will also answer questions about their health and fertility regularly.

Inclusion Criteria:

• Patients with documented sickle cell anemia (SCA).
• At least 8 years of age at the time of enrollment.
• Enrolled on the EXTEND or SACRED study.
• Provide informed consent.
• Able to take part in all parts of the study, including treatments, check-ups, and follow-up visits.

Exclusion Criteria:

• Currently taking part in another treatment study (not EXTEND or SACRED).
• Has received other treatments for sickle cell disease in the past 6 months.

People with sickle cell anemia who are at least 8 years old and seen in Jamaica and Dominican Republic.

Study data will be collected and managed using REDCap™ electronic data capture tools. REDCap™ is a secure, web-based application designed to support data capture for research studies, providing: 1) an intuitive interface for validated data entry; 2) audit trails for tracking data manipulation and export procedures; 3) automated export procedures for seamless data downloads to common statistical packages; and 4) procedures for importing data from external sources. The REDCap™ system is available for use through institutions participating in the REDCap™ consortium. Cincinnati Children's Hospital Medical Center serves as the home institution to allow the REDCap™ system for de-identified data collection in the SAFE study.