IVF Incubators: Does Newer Mean Better? A 2,152-Egg Trial Tests the Claim

Does a newer IVF incubator improve the chance of a baby? A randomized comparison of 2,152 mature eggs from 145 patients found a 51% blastocyst formation rate with both incubators and no statistically significant difference in live birth after embryo transfer.

As embryo culture technology advances, expectations for new equipment have grown. This US study suggests that a newer device does not necessarily guarantee better clinical outcomes.

The study was published in Fertility and Sterility on August 27, 2026.

Comparing a compact benchtop incubator with a conventional box incubator

An IVF incubator maintains temperature and carbon dioxide conditions while fertilized eggs develop toward the blastocyst stage.

Conventional box incubators have a relatively large culture space. Compact benchtop systems divide culture spaces into smaller compartments, potentially reducing temperature and gas changes when embryos are moved in or out.

That technical advantage has raised hopes of better embryo development and pregnancy outcomes. Whether it improves births requires clinical testing.

The researchers randomly assigned 2,152 mature eggs from 145 patients: 1,073 to a conventional box incubator and 1,079 to a compact benchtop incubator.

Blastocyst formation was 51% in both groups

Both devices produced a 51% blastocyst formation rate. Fertilization rates were 84% for the box incubator and 86% for the benchtop incubator, without a statistically significant difference.

Blastocysts generally develop five to six days after fertilization and are important for transfer or freezing. Their formation rate is one measure used to evaluate culture conditions.

The proportion of chromosomally normal embryos assessed by preimplantation genetic testing for aneuploidy, or PGT-A, was 69% with the box incubator and 66% with the benchtop device, again without a significant difference.

The comparison therefore did not demonstrate a clear advantage in fertilization, blastocyst formation or the proportion of euploid embryos.

Live birth: 61% versus 67%, without a significant difference

The investigators also examined outcomes beyond laboratory development.

Across 133 frozen embryo transfers, live-birth rates were 61% for the benchtop incubator and 67% for the conventional box incubator.

Although the box incubator's rate was six percentage points higher, the difference was not statistically significant.

The findings do not establish that the conventional system is superior. They also do not demonstrate that the newer compact system increases live birth.

A nonsignificant difference does not mean that the devices perform identically. The sample size and patient characteristics may limit the ability to detect smaller differences.

Participants were planning PGT-A and transfer of euploid embryos. The findings should therefore not be applied automatically to every patient or laboratory environment.

Laboratory quality matters beyond the age of the equipment

The study cautions against judging a laboratory solely by how new its incubators are.

Embryo development depends on medium properties, stable temperature and gases, handling procedures, air quality and quality management, as well as incubator type.

Introducing a newer incubator does not by itself establish a higher pregnancy rate. Technical advantages need objective testing against clinical outcomes.

The study does not dismiss advances in culture technology. It illustrates why improvements in equipment should be evaluated for their effects on development and birth.

The broader issue is the laboratory's ability to maintain a stable culture environment and consistent clinical performance.

Study source

This article is based on “The VILOCITY trial: validating incubators in the lab, optimizing culture and investigating blastulation yield, a randomized control trial,” published in Fertility and Sterility on August 27, 2026. Investigators included Blake Vessa, Francesca Barrett and Emre Seli, with institutions including IVIRMA New Jersey and Yale School of Medicine. DOI: 10.1016/j.fertnstert.2026.08.687. PMID: 42660380.