Pitocin (Oxytocin) - Warnings and Precautions
"Teratogenic Effects: Animal reproduction studies have not been conducted with oxytocin. There are no known indications for use in the first trimester of pregnancy other than in relation to spontaneous or induced abortion. Based on the wide experience with this drug and its chemical structure and pharmacological properties, it would not be expected to present a risk of fetal abnormalities when used as indicated."
Never heard of pitocin causing birth defects. It's the synthetic version of a hormone that your body already produces throughout pregnancy in small amounts anyway. I think there is more of a danger of spontaneously aborting with pitocin on board than birth defects. a splash on intact skin shouldn't be a problem, but if you are worried, I would ask your OB/GYN to be safe.