I'm now 25 weeks pregnant and my GI doctor has just recommended that I come off Humira one month before I am due to give birth. Apparently that is the most recent recommendation from the medical industry (NOT the drug manufacturer - they want you to stay on it), in order to reduce any risk of your immune system not coping with say, an infection if you end up having a c-section. Humira leaves your body after 10-20 days.
I will go straight back on when my baby arrives, as after-birth flares are a known phenomenon and I don't want to run the risk. The molecules in Humira WILL cross the placenta but only in very small amounts in the third trimester. But cannot pass through the breast glands into breast milk. The only other thing I'm aware of is that they don't recommend you give your child live vaccines, like norovirus, for the first 6 months of their life.
I tried to conceive for several years, in the end I believe I finally got pregnant because (a) I was in remission and eating a very clean diet; but also (b) I was taking vitex herb (Femaprin, available on Amazon) which supported progesterone production in my body. Crohn's and medications can really screw with your hormonal balance.
Good luck!!!