When we did scan 8th week after pregnancy and no heart beat was there. Hence we went for abortion.?

We did all check-up then for her including sugar, hemoglobin, Thyroid, Torch panel and all were normal. Only Prolactin is around 27 (normal must < 20). I also did semen ysis and it came out normal. Any reason for the miscarriage. Dr. gave her cabgolin 0.25 mg once per week for 4 weeks. She said then she can conceive after a month. We are married for 8 months now. Im 30 and she is 24. Please advise.