A prospective study of early pregnancy loss

The New York State Early Pregnancy Detection Study was a prospectivestudy of early pregnancy loss, between implantation and menses,in 217 women attempting to become pregnant during 1989–1992.Women collected urine samples on three consecutive morningsduring the late luteal phase of their menstrual cycle, for upto 12 cycles, contributing samples for 1253 menstrual cycles.Urinary human chorionic gonadotrophin (HCG), measured usingan immunoradiometric assay, was the biomarker for pregnancy.We observed a range of early pregnancy loss (EPL) rates, froma low estimate of 11.0% to a high estimate of 26.9%, dependingon the definition used and the subgroup analysed. Based on adefinition of 3 days of HCG concentration > 4.00 pmol/1,2 days 3=533 pmol/1 or the last, day of HCG 2 = 6.67 pmol/1,we identified 115 positive cycles; 95 cycles were clinicallyconfirmed pregnancies and 20 cycles were EPL, giving an EPLrate of 17.4% [95% confidence interval (CI) 11.0-25.6]. In addition,we observed an EPL rate of 19.5% (95% CI 113-30.1) for samplescollected within a 15 day window around menses, and a rate of203% (95% CI 113-32.2) for samples limited to the first threemenstrual cycles. Because studies use urine collection schemesother than daily sampling, the definition of pregnancy willbe crucial in defining EPL.