ObjectiveTo evaluate the predictive efficiency of serum estradiol (E2) concentration in the mid-luteal phase regarding chemical, clinical, and ongoing pregnancies, in patients subjected to IVF/ICSI with fresh embryo transfer.MethodsOne hundred and forty-three patients undergoing IVF/ICSI met all the inclusion criteria for the present study. Most of the patients used antagonists, final maturation was achieved with recombinant chorionic gonadotrophin (HCG), and embryo transfer took place on days 3 to 5, but mostly on day 4. The luteal phase was supplemented with estradiol valerate 6 mg/day and vaginal micronized progesterone 600 mg/day. There was no exclusion of patients in the embryo transfer group due to age or ovarian reserve. All patients with estradiol and chorionic gonadotrophin (βHCG) dosage on the day of transfer, day 7, were included. We assessed the following variables, initially regarding age: number of eggs collected, formed embryos, embryos transferred, day of transfer, transfer type, estradiol and chorionic gonadotropin. Next, we evaluated these elements at three different ranges of estradiol concentrations (<200 pg/ml, 200-500 pg/ml, and >500 pg/ml), comparing these parameters in pregnant (P) and non-pregnant (NP) patients.ResultsData analysis by age group in P and NP patients showed significant differences in the mean values of the variables E2 and βHCG, TD7. Mean serum estradiol levels in P and NP in the three age groups were: <35years, 835/417 p=0.0006, 35-39 years 833/434 p=0.0118, >39 years, 841/394 p=0.0012. There was also a significant difference in pregnancy rates in the group >500 pg/ml of estradiol concentration (63.4%, p=0.0096). The likelihood of chemical and clinical abortions for the estradiol ranges were: 38.46%, involving the two first ranges versus 15.15% for a concentration >500 pg/ml, p=0.0412 and 5.26% for a concentration >900 pg/ml, p=0.0105. The Pearson correlation coefficient for HCG and estradiol was r = 0.5108.ConclusionThis study showed the prognostic value of E2 in the mid-luteal phase (TD7) for chemical, clinical, and ongoing pregnancies, and its concentration suggested that there is a moderately positive correlation with βHCG levels.