Thomas Beatie, a small-business owner in Oregon, created a stir this week after announcing he is six months pregnant. Beatie, who was born female, underwent sexual reassignment surgery 10 years ago but, like many transgender people, kept his reproductive organs intact.

Among the issues raised by the pregnancy is whether a female-to-male transgender person who is pregnant might be endangering the fetus in the process. Especially patients such as Beatie who have been taking testosterone for 10 years or longer.

Michael Bartalos -- a New York geneticist and internist who works with many transgender patients -- says that he would be concerned about the health of the eggs in Beatie's body.

Because women are born with all the eggs they will carry for life, long time exposure to chemicals or hormones can have an adverse effect. Any possible damage done by 10 years of testosterone would be irreversible, he says. And even if Beatie's baby is born healthy, he says, "Who knows what might happen to her in 20 years? [The baby] could be at higher risk for certain types of cancer development."