Is finasteride and male fertility safe during pregnancy?

What does the evidence say about finasteride and male fertility during pregnancy?

1. Some men taking finasteride for hair loss or an enlarged prostate have had lower sperm counts, with levels improving after the medication is stopped. 1
2. Only small amounts of finasteride reach semen, and exposure through semen during sex isn't expected to be high enough to affect a pregnancy, though pregnant partners are still told to avoid handling crushed or broken tablets as a precaution. 2
3. A study following healthy young men on 1 mg of finasteride daily for 48 weeks found no effect on sperm production, even though separate case reports describe fertility problems in men who already had reduced fertility before starting the medication. 3
4. For men who are hesitant about their fertility on finasteride, the recommended step is a fertility evaluation with an andrologist, and finasteride should be suspended if fertility turns out to be reduced. 3
5. In an analysis of adverse-event reports, decreased semen volume was flagged disproportionately more often in men taking finasteride than in men taking minoxidil, a reminder that reproductive side effects are a real, if individual, possibility. 4

Is finasteride and male fertility safe in each trimester?

• First trimester. Early in trying to conceive, this is worth a quick conversation with a prescriber rather than something to quietly stop or start on your own. A 48-week study of healthy young men on a standard 1 mg daily dose found no measurable effect on sperm production, so most men on finasteride don't need to change anything right away.
• Second trimester. If several months of trying to conceive have passed without success, sperm-count effects vary a lot by individual, so this is a reasonable point to ask a provider whether a semen analysis makes sense before assuming finasteride is the cause.
• Third trimester. For couples moving toward a fertility workup, guidance is that finasteride should be suspended and fertility assessed with an andrologist if sperm counts turn out to be low, since counts have been reported to recover after the medication is stopped.