Time from oocyte retrieval to frozen embryo transfer in the natural cycle does not impact reproductive or neonatal outcomes

ObjectiveTo determine if the time from oocyte retrieval to frozen embryo transfer (FET) in natural cycle affects reproductive or neonatal outcomes.DesignRetrospective cohort.SettingNot applicable.Patient(s)Five hundred and seventy-six consecutive freeze-all cycles January 2011 December 2018 followed by FET of a single blastocyst.Intervention(s)None.Main Outcome Measure(s)Primary outcome live birth; secondary outcomes preterm delivery (24–37 weeks) small for gestational age (SGA) with multivariable logistic regression performed adjustment age, infertility diagnosis, ovulatory trigger type, preimplantation genetic testing (PGT).Result(s)Before confounding, we found statistically significantly different live-birth rate (57.7% vs. 48.6%) occurring first versus second menstrual cycle, respectively. In multivariate analysis, performing blastocyst compared did not impact odds rate. After only PGT was associated increased birth no PGT. There were differences incidence SGA (male, 6.6% 2.3%; female, 9.8% 11.1%) (1.6% 5.6%) between both groups.Conclusion(s)Performing after ovarian stimulation outcomes. To Retrospective cohort. Not applicable. Five blastocyst. None. Primary (PGT). Before groups. Performing