Thank you very much for contacting healthcare magic. In pregnancy of second or third trimester charly horse in calf muscle is common complain. In uterus there is more pressure created that cause decrease blood supply to calf muscles . Whenever pain occur on your calf muscle you can stand on hard floor and try to lift your toe. It may helpful. Try to massage your leg by firm strock towards foot. Still pain is present than you can use warm cloth or warm water bath may helpful. Don t seat or sleep on same position for long period of time. Try to relax your leg at night time that helpful on this condition. Wish you a good health. Take care. Thank you very much.