Analysis of Human Chorionic Gonadotropin Levels in Normal and Failing Pregnancies [40

Abstract

INTRODUCTION: Serum human chorionic gonadotropin (hCG) measurement often is used for assessment of pregnancy viability. Urine hCG levels closely mirror those in serum, providing a noninvasive monitoring method. This study examined daily urinary hCG to assess pregnancy viability. METHODS: Daily urine samples from 129 women who became pregnant were collected from last menstrual period. Levels of hCG and luteinizing hormone were measured by AutoDELFIA. Miscarriages (n=44) were classified into early losses (less than 6 weeks) and clinical losses (after 6 weeks). Day of ovulation assigned gestational age. Longitudinal models were created to profile hCG levels. Cox proportional hazards model was used to identify miscarriage risk factors (demographic and hCG level). RESULTS: Models showed a significant difference between the early loss group and the other two groups. Early loss profiles rose rapidly (10–14 days from ovulation) before dropping. Clinical losses and healthy pregnancies had a steady increase in hCG level before plateau 30 days postovulation. Factors relating to high risk of miscarriage were maternal age, longest reported cycle length, and time from ovulation to hCG's reaching 25 milli-international units/mL. The latter was of particular importance because each additional day increased risk by 44% (hazard ratio 1.44, 95% confidence interval 1.25–1.66). CONCLUSION: Urinary hCG profiles in viable pregnancies are consistent but significantly different from those in early losses, making early loss identifiable by hCG trajectory before any clinical symptoms. The most significant predictor was delay of appearance of hCG after ovulation. Level of hCG could not consistently differentiate between viable pregnancy and loss after 6 weeks before onset of loss.