Document Type : Original Article
Department of Endocrinology and Female Infertility, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran
Reproductive Epidemiology Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran
Background: To detect the predictive value of beta human chorionic gonadotropin (β-hCG) levels 16 days post
embryo transfer (ET) regarding detection of an ectopic pregnancy (EP) in assisted reproductive technology
Materials and Methods: In this cross-sectional study, we reviewed the database of Royan Institute from January
2011 to December 2014 and from January 2017 to December 2019 retrospectively. All cases with positive β-hCG
levels sixteen days after ET were screened (n=4149). The pregnancies with oocyte or embryo donation and the multiple
pregnancies based on the first ultrasound were excluded. All eligible singleton pregnancies with documented
serum β-hCG levels at Royan institute laboratory (n=765) were included and then classified according to the type
of pregnancy: EP (n=189) or non-EP (n=576). The data of the treatment cycle was extracted from the patients’ files.
A receiver operating characteristic (ROC) curve was used to detect the predictive power of the first measurement
of β-hCG level in distinguishing EP from ongoing pregnancy in the ART and intrauterine insemination (IUI) cycles
separately. Sensitivity, specificity, area under the ROC curve and 95% confidence intervals (CI) were calculated for
each of the estimates.
Results: The mean levels of β-hCG 16 days after ET were remarkably higher in the ongoing pregnancy group than
the EP group (1592.35 ± 87 IU/L vs. 369.69 ± 50.61 IU/L, P<0.001). The β-hCG thresholds predictive of ongoing
pregnancy were 278 IU/L as the most suitable cut-off to predict viable pregnancy with a sensitivity of 72.8%, a
specificity of 67.5%, a positive predictive value of 77.8%, standard error of 0.02, and a confidence interval of 73.8-
81.7%. However, this relationship was not found in IUI cycles.
Conclusion: Based on these findings, if β-hCG levels 16 days after ET are below 278 IU/l, close follow-up is recommended,
until either the diagnosis of EP or miscarriage is established.