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 si gnificance of initially low serum early human chorionic gonadotropin levels in in vitro fertilization pregnancies that progress to an intrauterine ges tational sac. STUDY DESIGN: This retrospective cohort study compared 65 in vitro fertiliz ation pregnancies with an initial human chorionic gonadotropin value at 4 w eeks of less than or equal to 20 mIU/mL with 130 pregnancies with human cho rionic gonadotropin values > 20 mIU/mL. All pregnancies had a singleton int rauterine sac at 6 weeks' gestational age. Spontaneous abortion rates and p regnancy complications were compared. RESULTS: Women with a low initial serum human chorionic gonadotropin level showed a statistically significant increase in first-trimester pregnancy lo ss (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 significan t differences. CONCLUSIONS: In vitro fertilization pregnancies with a low initial human ch orionic gonadotropin value, despite progressing to a gestational sac, are a t an increased risk of spontaneous abortion.