The purpose of this guideline is to provide guidance on the investigation and treatment of couples with three or more first-trimester miscarriages, or one or more second-trimester miscarriages.

Miscarriage is defined as the spontaneous loss of pregnancy before the fetus reaches viability. The term therefore includes all pregnancy losses from the time of conception until 24 weeks of gestation. It should be noted that advances in neonatal care have resulted in a small number of babies surviving birth before 24 weeks of gestation.

Recurrent miscarriage,defined as the loss of three or more consecutive pregnancies,affects 1% of couples trying to conceive.1 It has been estimated that 1–2% of second-trimester pregnancies miscarry before 24 weeks of gestation.