Hi Liz
Welcome to the forum!
I did read something recently about this I'll try and find it again! There are studies ongoing on this but in the meantime I believe the advice is to stop Enbrel before TTC and remain off it until after the birth. Enbrel doesn't stay in the system very long, couple of months from my experience of stopping, but then you are left with finding a suitable alternative. It might be possible to put you on a DMARD prior to conceiving; often symptoms go into remission during pregnancy and no medication at all is needed.
This is definitely one for your rheumatologist as they will need to be involved in your care throughout any pregnancy. The choice of appropriate medication is an important one for your peace of mind and control of the disease.
I wish you luck,
Lyn x