A prospective study of spontaneous miscarriage in ultrasonically normal pregnancies and relevance to chorion villus...

A total of 1,068 patients were examined by ultrasound to ensure normality of pregnancy and followed prospectively from booking until 28 weeks. The spontaneous miscarriage rate was 2.7 per cent occurring within the first 16 weeks. Threatened miscarriage was associated with a 38 per cent fetal loss. Miscarriage was less likely as pregnancy advanced. The reduction in subsequent miscarriage rate before 11 weeks and from 11 weeks onwards is statistically significant (p less than 0.001). Gravidity, maternal age and a history of previous fetal loss did not contribute significantly to the miscarriage rate. Patients with a history of fetal loss were more likely to experience a threatened miscarriage. The relevance of these findings to chorion villus sampling is discussed.