In a patient with sickle cell disease on hydroxyurea who is planning to have a family, for how long should they be off the drug before trying to conceive?

There is some consensus that pregnant women should not take hydroxyurea and should stop taking this when found to be pregnant. (Smith-Whitley, PMID 25472967) As far as I know, there is no data on how long hydroxyurea should be discontinued in either men or women before attempting pregnancy. In fact, there is also little evidence that hydroxyurea has adverse effects on human reproductive outcomes. (Ballas et al., PMID 19860305) My recommendation, based on no evidence, is that when a couple where either partner is taking hydroxyurea is considering pregnancy, they continue contraception for a few weeks after stopping the drug.