Doyle and colleagues Doyle y colegas han reportado el siguiente conjunto de datos más grande hasta la fecha, incluyendo tasas de nacidos vivos después de descongelar 1,283 óvulos vitrificados y posteriormente descongelados entre 2009 y 2015. Este es uno de los conjuntos de datos publicados más grandes disponibles. Aunque no se transfirió cada embrión creado a partir de estos óvulos congelados, los autores estimaron las tasas de nacidos vivos como si se hubiera transferido cada embrión viable en etapa de blastocisto. Como referencia para pacientes de mayor edad que tenían menos embriones, utilizaron sus tasas de éxito de resultados de FIV: previamente habían demostrado que los embriones en etapa de blastocisto provenientes de óvulos congelados tenían al menos la misma tasa de embarazo y de nacidos vivos que los embriones en etapa de blastocisto de mujeres de la misma edad usando óvulos frescos nunca congelados. Sus resultados publicados incluyeron los siguientes cálculos:
- Calculate the number of live births from frozen eggs from women at various ages.
- They still had embryos (blastocysts) remaining from the frozen eggs that were not transferred and refrozen, so they estimated how many of those frozen blastocyst embryos would result in a live birth based on their experience with blastocyst stage embryos frozen from women of the same age (at the time the eggs were retrieved). This estimate allowed them to approximate the efficiency per egg.
- Since this number looked unrealistically high for women at age 41-42, they substituted the efficinecy of live birth per fresh oocyte at this age and applied this number to the eggs that survived freezing/warming.
This study lacked extensive data on eggs frozen from women who are older than 37 (only 96 eggs). The 96 warmed eggs from women over age 37 yielded 5 babies. These numbers gave an unusually high efficiency for women over age 37 so the authors correctly adjusted their data to “predict” the efficiency using:
- Their survival rate for frozen eggs.
- The anticipated number of blastocysts that would develop from those eggs.
- Their live birth rates using blastocysts derived from fresh (non-frozen eggs) at each age group.
They then assumed a binomial “normal” distribution to yield the predicted probability per frozen oocyte at each age group. Our calculator uses the same assumption (a binomial distribution) to arrive at the probability of 1 or multiple children based on the number of eggs and the probability of a live birth per egg.
They arrived at the following estimates for live birth efficiency per egg:
| Doyle et al 1,283 warmed eggs |
| <30 |
8.2% |
| <35 |
8.0% |
| 35-37 |
7.3% |
| 38-40 |
4.5% |
| 41-42 |
2.5% |
