Clinical associations of recurrent miscarriage

Abstract

Recurrent miscarriage is defined as three or more pregnancies ending before 28 weeks from the date of the last menstrual period. It is important to distinguish between a miscarriage which is a single isolated event in a woman’s reproductive history, and miscarriage which recurs repeatedly in women who have either had no pregnancies beyond 28 weeks (primary or 1° miscarriers) or, less commonly, have had at the most one or two pregnancies after 28 weeks (secondary or 2° miscarriers). A single miscarriage is common (≃ 15%), frequently being associated with a non-recurrent chromosomal abnormality of the conceptus. ⁽¹⁾ Recurrent miscarriage is much less common (probably less than 1 % in the population), and as such is likely to be due to a single cause which may have a variable influence on the wellbeing of the conceptus at all stages of pregnancy. This latter concept is borne out by the study of 2° miscarriers by Reginald et al ⁽²⁾ which revealed a high prevalence of small for gestational age babies, preterm delivery and perinatal mortality amongst these women when they became pregnant. These findings support those of earlier studies on women who have had two or three miscarriages.^(3,4,5) There was no evidence for an increase in the prevalence of fetal abnormalities.