Fran, sounds like you are using your electric blanket the way MKS wanted to use a mattress pad!
Since you're pregnant, did you check with your OB whether it's safe to use electric blankets during pregnancy?
I'd LOVE to have an electric blanket myself, but since I practice Natural Family Planning, I have to take my temperature every morning. Using an electric blanket would artificially raise my waking temp

so I settle for an extra wool blanket, doubled over on my side of the bed.
As far as the heat goes, have you tried a cool mist humidifier in the room while you sleep? It has helped me tremendously.