Help pregnant with husband cancer treatments

Dawn • Baby girl to arrive April 21

I just found out I’m pregnant. Probably around 11 weeks. I didn’t notice because 6 weeks ago we found out my husband has stage 3 cancer and he started chemo three weeks ago. The baby will be born only a month after he is done chemo. We have two other children both of which took 18/16 months each of trying to get pregnant to work now we had unprotected sex ONCE! And it worked!!! I don’t understand and I’m in shock. Anyone have any experience I can ask questions to?