Last night after I got the estrogen patch "system" I just about freaked out when I read the patient material. In big bold capital letters, the box and the pamphlet said to NOT take it if you are pregnant. It said that although the risk is slight, it may cause birth defects, and that estrogen does not prevent miscarriage. After fretting about it for a while, I decided to wait until this morning, call the nurse for an explanation, and then apply the first patch if her answer satisfied me. She asked why I had been prescribed the estrogen (she wasn't the nurse I saw on Friday) and said that all synthetic hormones have to have that warning, but that they consider this drug safe. They even used to prescribe it for all women having FETs. This is at least the 2nd, if not the 3rd, medicine that I have taken as part of the IVF treatment that specifically says to not use in pregnancy. It's too bad that the labeling doesn't include the common exception of hormone use in infertility treatment as part of the information.