Arm & foot numbness while sleeping

Hello,

I have had a problem for the past year or so with my hands, arms, or feet falling asleep while I sleep, particularly on my back. It happens intermittently, however, the occurances increased in frequency during my last pregnancy at around 8 weeks. At the same time, I had an onset of migraine headaches, and the pregnancy ended in miscarraige (miscarriage) a few weeks later. After the miscarraige (miscarriage), the numbness happened much less frequently again. Sometimes, I think it may be related to hormone changes and my monthly cycle. I am 37 years old ... any thoughts on what could be causing this? Thanks for your input.