I have stage II endometriosis, and we have been trying to conceive for four and a half years. My husband and I were preparing to do IVF in December, so after ovulating in November I started taking Lupron. While waiting for my next cycle to start before fertility treatment could begin, I discovered I was pregnant. Since I had never been pregnant before, I was carefully monitored. My hCG levels did not increase as they should have, and at seven weeks there was no fetal heartbeat. The doctors advised me to have a D&C, and it was determined that it was a molar pregnancy. Could the Lupron have caused a molar pregnancy? Alternatively, could Lupron have actually helped me get pregnant, and then subsequently killed the embryo?

L.F.

Lupron is a GnRH-agonist that is used with in vitro fertilization (IVF) to synchronize egg development and prevent ovulation from occurring early, before the eggs can be retrieved. If Lupron is started before ovulation, large ovarian cysts can occur. As these cysts can delay the start of IVF treatment, it is better to wait until about a week after ovulation to minimize the risk of cyst formation. In my clinic, we advise our patients to avoid pregnancy before beginning Lupron. This either means avoiding intercourse or using a barrier method of contraception.

Although Lupron does not appear to cause birth defects, ovulation and pregnancy that occurs with the start of Lupron therapy may be associated with a higher risk of miscarriage. After ovulation, the follicle (the structure on the ovary that held the developing egg) -- now called the "corpus luteum" -- produces both estrogen and progesterone necessary to support the early pregnancy. For a few weeks, the corpus luteum function depends on secretion of the hormones LH and FSH by the pituitary gland. Lupron suppresses these hormones, so the corpus luteum may have trouble carrying out its work. After a few weeks, the developing placenta produces enough of the hormone hCG to support the corpus luteum, so after that point, suppression of pituitary function by Lupron would have minimal effect on corpus luteum function.

There are no published reports linking Lupron to molar pregnancy. In most cases of molar pregnancy, the cause is thought to be a chromosomal anomaly in which sperm chromosomes are present, but the embryo lacks the egg's genetic contribution. As you most likely ovulated before you began the Lupron therapy, Lupron would not have been able to affect the embryo's chromosomes.