The predictive value of fresh embryo transfer pregnancy results on frozen embryo transfer outcomes: a cohort study.

OBJECTIVE

To investigate whether the outcome of a fresh embryo transfer can predict the results of subsequent frozen embryo transfers (FET) in patients undergoing single blastocyst transfer.

DESIGN

Retrospective cohort study.

SETTING

Tertiary-care academic medical center.

PATIENTS: This retrospective study involved a total of 6,491 women who underwent single blastocyst transfer in FET cycles from January 2016 to June 2024. Women were categorized into four groups based on their fresh transfer outcomes: the non-pregnancy group (n=3,711), biochemical pregnancy group (n=701), miscarriage group (n=1,066), and live birth group (n=1,013).

INTERVENTIONS: None.

MAIN OUTCOME MEASURES: Live birth rates.

RESULTS

Compared with the fresh-cycle live birth group, patients in fresh-cycle non-pregnancy, biochemical pregnancy, and miscarriage groups exhibited significantly lower chance of subsequent biochemical pregnancy (adjusted odds ratio [aOR]=0.58, 95% confidence interval [CI]: 0.50-0.68; aOR=0.70, 95% CI: 0.56-0.87; aOR=0.72, 95% CI: 0.60-0.88, respectively), clinical pregnancy (aOR=0.57, 95% CI: 0.49-0.66; aOR=0.65, 95% CI: 0.53-0.80; aOR=0.71, 95% CI: 0.59-0.85, respectively), and live birth (aOR=0.59, 95% CI: 0.51-0.68; aOR=0.71, 95% CI: 0.58-0.86; aOR=0.65, 95% CI: 0.54-0.77, respectively). However, no significant differences were observed in the rates of miscarriage or ectopic pregnancy among the four groups (P>0.05 for all). Further subgroup comparison demonstrated that compared with fresh-cycle non-pregnancy group, patients with prior fresh-cycle miscarriage had significantly higher rate biochemical pregnancy (aOR=1.12, 95% CI: 1.04-1.20), clinical pregnancy (aOR=1.12, 95% CI: 1.05-1.21), and miscarriage (aOR=1.14, 95% CI: 1.03-1.26), whereas the rates of ectopic pregnancy and live birth were remained comparable between the two groups (P>0.05 for all).

CONCLUSIONS

In conclusion, compared with patients who achieved live birth in the fresh cycle, those in the non-pregnancy, biochemical pregnancy, and miscarriage groups had significantly lower chances of achieving biochemical pregnancy, clinical pregnancy, and live birth in subsequent FET cycles. These findings suggest that the outcome of fresh embryo transfer can serve as a potential predictive indicator for subsequent FET pregnancy prognosis, providing valuable clinical guidance for individualized counseling and management of patients undergoing assisted reproductive technology (ART) treatment.