Pregnancy in older women places a greater demand on nutrients.

Leg cramps? These will probably get worse, since pregnancy causes spasms
itself. I hope you are trying magnesium for those spasms now, because magnesium is excellent during pregnancy and your requirement for it is higher.

Secondly, Omega-3s are very important and there are several brands of prenatal now that have them. So I would make sure you are taking one of those
newer ones.

If your PN is inflammatory in type, you may see a reduction of symptoms during pregnancy. That is because cortisol levels increase quite a bit during pregnancy.
In fact many women with RA show remissions then. But often flare when the
pregnancy is over.

Older women also have more potential for thyroid disease to appear during a pregnancy and that should be monitored well for you. At 46 you will need a very thorough OB-GYN...to track you safely.

Near the end the swelling of hands and feet may increase discomfort pinching the nerves etc.

Using fertility drugs is difficult...there are many side effects. So that is hard to predict for you.