The Epidemiology of Recurrent Miscarriage: A Descriptive Study of 1214 Prepregnant Women With Recurrent Miscarriage

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ABSTRACT An estimated one in 100 women experiences recurrent miscarriage, defined at the investigators' Recurrent Miscarriage Clinic (RMC), located at the National Women's Hospital in Auckland, New Zealand, as 2 second-trimester or at least 3 first-trimester pregnancy losses. This study was a retrospective review of the characteristics of 1214 prepregnant women attending the RMC compared with those of women in the hospital's overall obstetric population in the years 1986 through 2003. Women seen at the RMC were older than the general obstetric population at the same institution but were of the same racial or ethnic background (52% New Zealand European, 14% Maori). No difference in parity was evident (median parity = 1), but the median gravidity of the RMC women was 5. Approximately one fourth of each group smoked before pregnancy. The RMC group had relatively high rates of a personal or family history of antepartum bleeding, fetal abnormalities, stillbirths, or neonatal deaths; and approximately 11% had been treated for infertility before being referred to the clinic. A history of stillbirth or neonatal death was reported by 8% of women, and the rate of antepartum hemorrhage was 8.4%. Fifteen percent of the women reported a personal history of fetal anomalies, including structural defects and syndromic or chromosomal disorders, and 16% reported such a history in their families. Chromosome anomalies such as translocations (n = 52) and mosaicism (n = 24) were detected in 86 women; 142 had reproductive tract anomalies such as bicornuate uterus (n = 21) or fibroids (n = 20), and 32 had a thrombophilia (activated protein C resistance). Newly diagnosed endocrine abnormalities were present in 79 women, including polycystic ovary syndrome in 49, thyroid dysfunction in 16, and type II diabetes in 14. Fifteen percent (n = 182) had antinuclear antibodies, 5% (n = 63) had extractable nuclear antigens, anticardiolipin antibody was found in 14% (n = 165), and 3% (n = 33) had lupus anticoagulant. Fifty-three percent of the RMC patients had no identifiable cause for recurrent miscarriage. These findings indicate that the women seeking care in the RMC had a high incidence of medical or obstetric problems and fetal abnormalities. Their disorder is therefore distinct from subfertility, and requires a structured diagnostic and therapeutic protocol suited to their particular needs.