Early serum β-human chorionic gonadotropin in pregnancies after in vitro fertilization: contribution of treatment variables and prediction of long-term pregnancy outcome

Objective: Low initial serum βhCG is a good predictor of early pregnancy failure. We sought to determine the contribution of treatment variables and the predictive value of early serum βhCG after IVF on long-term pregnancy outcome. Design: A retrospective case-control study. Setting: An academic IVF unit. Patient(s): Five hundred thirty-three IVF cycles performed between 1999 and 2004, which resulted in a positive serum βhCG level (>10 mIU/mL) on day 13 after embryo transfer (ET). Intervention(s): The study group included 281 pregnancies with initial βhCG ≤150 mIU/mL on day 13 after ET. Randomly selected 252 IVF cycles with initial βhCG >150 mIU/mL comprised the control group. Characteristics of the patients and the treatment protocols were analyzed using logistic regression, Pearson's chi-square, and Fisher's exact test. Main Outcome Measure(s): Primary pregnancy outcome was defined as favorable when a fetal pulse was detected, testifying to a viable gestation. Unfavorable outcome referred to chemical or ectopic pregnancies, as well as spontaneous abortions. Additionally, the two groups were followed throughout gestation. Secondary pregnancy outcome was based on the following parameters: gestational age at delivery, method of delivery, and birth weight. Result(s): Poor primary pregnancy outcome was encountered in 64.8% of the study group and in 22.2% of the control group. Predictors of unfavorable primary pregnancy outcome were older age, use of a short protocol, and shorter than anticipated crown-rump length. No difference was found in the secondary pregnancy outcome between the groups. Preterm labor was more prevalent in the study group, but the difference did not reach statistical significance. Conclusion(s): Pregnancy viability can be predicted by measuring serum βhCG as early as on day 13 after ET. Older age, use of a short protocol, and shorter than anticipated crown-rump length are associated with early pregnancy loss. Of those who reach delivery, no significant adverse outcome is anticipated in IVF pregnancies with low initial serum βhCG.