Miscarriage Reasons:-hormonal imbalance, abnormalities of the womb, weakness of the cervix and certain infections like listeria and German measles (rubella).

http://www.patient.co.uk/health/miscarriage-and-bleeding-in-early-pregnancy

There are other less common causes of miscarriage. These include: hormonal imbalance, abnormalities of the womb, weakness of the cervix and certain infections like listeria and German measles (rubella). Alcohol abuse, cigarette smoking, illicit drug use and obesity may also increase the risk of miscarriage.