If you find yourself getting up in the middle of the night with severe pain in the calves, then the first thing to do is ensure that you are consuming enough water. Ideally, you need to consume at least 8-12 glasses of water every day.
Watch out for cramps in the lower abdomen which are intermittent and come and go at periodic intervals. These could be pre term contractions and an indication that the cervix is starting to shorten ahead of time.
If you experience such cramps, contact your doctor. The doctor may recommend a cerclage, which is a cervical stitch to hold the cervix in place and help carry a pregnancy to full term.