There are low concentrations in semen but it does not affect the baby nor pregnancy in any known way based on all studies to date. The main side effects are decreased libido and erectile dysfunction and ejaculatory problems. A small minority of men report permanent or persistent issues. This information should be frequently reviewed with the prescribing doctor for updated information as it may change over time as new information emerges. At the present time, there is no clear evidence that use of finasteride by men increases the risk of birth defects in his children. 1-3 % of all children in the world are born with birth defects and this rate at present seems similar in finasteride users compared to non users. About 1 out of every 100 men who use finasteride while fathering a child will have a baby with a birth defect of some kind - but that rate is similar to men who did not use finasteride. Several agencies currently advise that finasteride not be used by males whose partners are trying to conceive. Several agencies state that there is no reason for it to be stopped. There is no evidence at present to support either the recommendation not to take or the recommendation to take. References are stated below this page. Men with a genetic deficiency of 5 alpha reductase (i.e. men with genetic mutations) may have hypospadias (abnormal opening of urethra), cryptorchidism (undescended testes) and abnormal genitalia. These side effects do not appear increased in men using finasteride based on information available today. Many of these side effects are common in the general population. For example, 3 % of all boys in the world are born with cryporchidism making it a very common abnormality in the world’s population. Similarly 1 in 200 boys are born with hypospadius making it also one of the more common birth defects. In fact, hypospadius is the second most common congenital abnormality after cryptorchidism. We do not have evidence at present to suggest that men using finasteride have a higher than 3 % risk of having a boy with cryptorchidism or higher than a 1:200 risk of hypospadius. At present, all evidence would suggest that 3% of all men who use finasteride would have a baby boy born with cryptorchidism -the same rate as the general population. Similarly, all evidence would suggest that 1 in 200 men who use finasteride would have a baby boy born with hypospadius - the same rate as the general population. It's important to be aware that finasteride can lower semen volume in some men. Therefore, men may wish to stop finasteride if there is any issues regarding fertility in the couple. Women, however, must never use finasteride during pregnancy and must never touch crushed tablets. All men using finasteride should review the use, indications, contraindications and side effects with their physicians before using and at regular intervals after being on the medication.