Embryo morphology and live birth in the United States

Assisted Reproduction

VOLUME 3, ISSUE 2, P131-137, JUNE 01, 2022


Michael S. Awadalla, M.D., Jacqueline R. Ho, M.D., Lynda K. McGinnis, Ph.D., Ali Ahmady, Ph.D., Victoria K. Cortessis, Ph.D., Richard J. Paulson, M.D.



To determine the best-fit live birth rate per embryo based on maternal age, embryo stage, and embryo morphology.


Retrospective data analysis.


Fertility clinics.


The patients included were treated with in vitro fertilization in the United States at clinics reporting data to the Society for Assisted Reproductive Technology Clinic Outcomes Reporting System. We analyzed live birth data of unbiopsied autologous cleavage and blastocyst stage embryos for cycles started from 2016 through 2018. The analysis included 223,377 embryo transfers with a total of 336,888 embryos.



Main Outcome Measure(s)

Live birth rate per embryo and rate of multiple gestations per pregnancy.


At the mean maternal age of 34 years, fresh embryos produced live birth rates of 19%, 38%, 26%, and 27% for embryos aged 3, 5, 6, and 7 days, respectively. At the age 34 years, live birth rates for day 5 fresh embryos by overall morphology grade were 43% for good, 30% for fair, and 21% for poor. For the transfer of 2 fresh day 5 blastocysts, the rate of multiple gestations per pregnancy was 47% at 25 years old, 44% at 30 years old, 35% at 35 years old, and 23% at 40 years old.


The analysis of pregnancy data in the Society for Assisted Reproductive Technology database can be used to calculate live birth rates per embryo based on maternal age, embryo age, and morphology. This information can be used for evidence-based decision making, quality control, and planning multicenter studies.

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Go to the profile of Pandiyan  Natarajan
29 days ago

Maternal age is the single most important determinant of Live birth rates.

The single most important determinant of successful outcome of an IVF cycle is Maternal age. IVF does not seem to overcome this age related decline in Fertility.

Embryo age seems like a determinant. It may well be in a given cycle at the cost of Frozen embryos. It is unlikely to be so, if cumulative pregnancy rate per oocyte recovery is taken into consideration. Day 5 transfer comes at the cost of few embryos which are unlikely to progress to Day 5. Whereas in Day 3 transfer, it is likely that the patient would still have more embryos to freeze. Therefore, the best comparison of Embryo age would be to consider cumulative pregnancy rate from an oocyte retrieval cycle between Day 3 and Day 5 transfer. 

I fail to understand the need or the reason for Day 6 or Day 7 transfer. An embryo is any day better off in Vivo, back in the uterus, than in vitro, however good the laboratory is. Prolonged culture of Embryos in the laboratory may also induce Epigenetic changes in the Embryo.

Professor Dr Pandiyan Natarajan.

Chief Consultant in Andrology and Reproductive Sciences,


Chettinad Super Speciality Hospital (Retired)

Professor Emeritus, The Tamil Nadu Dr MGR Medical University.