Yes. And No.
This is complicated.
I had to have an emergency partial hysterectomy a year before my MG was diagnosed.
Doc left ovaries. But I did not have the "cycle" anymore. So I can't say yes or not definitively.
A couple of years after MG diagnosis, gyn said I needed to take estrogen supplements to help with estrogen.
However, when I started on oral estrogen supplemention - my MG was greatly exacerbated. Not to point of crisis. I had to stop taking oral estrogen.
Here is a little PubMed statement about menstrual cycle and myasthenia gravis:
http://www.ncbi.nlm.nih.gov/pubmed/9559997