Can a uti or yeast infection cause a miscarriage?

Possibly... A UTI can turn into a kidney infection and spread to the blood and result in a serious blood infection (Sepsis) that could cause a miscarriage or pre-term delivery. A yeast infection usually doesn't cause major problems, though it can cause pre-term contractions by irritating the cervix. Its best to get these types of infections treated ASAP to prevent problems. Best wishes!