I was born with one testicle. Can it be side effect from birth control mother took while pregnant?

It is possible that exposure to certain medications during pregnancy can lead to congenital abnormalities in the male reproductive system, including undescended or absent testicles. However, the exact causes of these conditions are not always known, and they can occur for a variety of reasons.

Some medications that have been associated with an increased risk of congenital abnormalities of the male reproductive system include hormones, such as diethylstilbestrol (DES), and some anti-seizure medications. However, it is important to note that not all women who take these medications during pregnancy will have children with these conditions, and not all cases of undescended or absent testicles are caused by medication exposure.

It is also worth noting that some men are born with only one testicle, even in the absence of any medication exposure or other known risk factors. This is known as monorchism and is a relatively rare condition that affects approximately 1 in 5,000 men.