Help! My obgyn discovered I was pregnant yesterday (great) BUT had all missed the preg early on and I took Letrozole for my next IUI treatment. Ive read horrible things online about birth defects and am terrified. I am apparently 5 weeks along.

I am wondering why they didn't do a pregnancy test before starting you on the next cycle of medication - that seems careless. But perhaps they did and false negatives have been known to occur.

Letrozole is not an ideal medication to take while you are pregnant. However, it is not necessarily a reason to be scared. Concerned, yes - but not terrified.

Recently, the manufacturer of Letrozole sent a notice to doctors warning that there are reported cases of birth defects that arose in the children of women who received Letrozole while pregnant. Novartis, the manufacturer of letrozole, reviewed their safety database and found 13 reports of pregnant women receiving the drug worldwide. Of those 13 women, two had children with birth defects. In the United States, the labeling of letrozole already warns that it has been associated with birth defects. Novartis has never sought FDA approval to market letrozole as a fertility medication and is clearly concerned about their liability if given in pregnancy.

Letrozole is a medication that is metabolized rapidly in the body. It is not thought to have significant levels in the blood or tissues for a prolonged period of time.

The odds are still in your favor, and the best thing you can do at this point is get a referral to a neonatal specialist to determine what kinds of tests are available and appropriate for your situation.