Differences in the Percentage of Normal Embryos Across Labs
A study published in Human Reproduction by Munné et al. examined how chromosomally normal embryo rates vary across different embryo laboratories. People frequently question what distinguishes one fertility center from another. Two programs may appear to offer identical services, yet outcomes can differ significantly depending on the specific physician and facility chosen.
Striking Research Findings
The study analyzed 1,645 egg donor cycles and 13,282 blastocyst biopsies across 42 US fertility clinics, all using the same PGS laboratory and technology to eliminate method-related variables. The findings were striking:
The average rate of euploid (chromosomally normal) embryos ranged from 39.5% to 82.5% across different fertility centers — using identical donor eggs and identical testing methods.
While the retrospective study has limitations, the magnitude of differences strongly suggests that laboratory practices and physician-directed ovarian stimulation protocols significantly impact results.
Where Does the Difference Come From?
Potential explanations include variations in ovarian stimulation protocols between centers, and laboratory-specific practices — including incubator types, gas concentrations, and culture media — that influence embryo development during early cell divisions.
Despite surface similarities between programs, deeper evaluation reveals substantial differences. The embryo lab is invisible to patients, but it may be the most important factor determining outcomes. Asking about blastocyst development rates and laboratory infrastructure is as important as asking about success rates.
