Evaluation of the prognosis of in vitro fertilization pregnancies with initially low serum human chorionic gonadotropin levels

OBJECTIVE: The objective of this study was to investigate the prognostic significance of initially low serum early human chorionic gonadotropin levels in in vitro fertilization pregnancies that progress to an intrauterine gestational sac. STUDY DESIGN: This retrospective cohort study compared 65 in vitro fertilization pregnancies with an initial human chorionic gonadotropin value at 4 weeks of less than or equal to 20 mIU/mL with 130 pregnancies with human chorionic gonadotropin values > 20 mIU/mL. All pregnancies had a singleton intrauterine sac at 6 weeks' gestational age. Spontaneous abortion rates and pregnancy complications were compared. RESULTS: Women with a low initial serum human chorionic gonadotropin level showed a statistically significant increase in first-trimester pregnancy loss (36.5% vs 9.2%; odds ratio, 5.7; 95%; confidence interval, 2.6, 12.4; P < .0001). Once pregnancies progressed to 13 weeks, there were no significant differences. CONCLUSIONS: In vitro fertilization pregnancies with a low initial human chorionic gonadotropin value, despite progressing to a gestational sac, are at an increased risk of spontaneous abortion.