A new study in mice suggests that culturing IVF embryos at lower oxygen levels could lead to better fetal and placental development. Researchers found that 2 per cent oxygen more closely matched natural conception than the current 5 per cent standard. The findings were published on bioRxiv.
Marisa Bartolomei at the University of Pennsylvania and her team cultured mouse embryos at either 2 per cent or 5 per cent oxygen before transferring them to recipient mice. They tracked the offspring for 12 weeks after birth.
Embryos grown at 2 per cent oxygen showed epigenetic patterns closer to those of naturally conceived embryos. In contrast, those at 5 per cent had more trophectoderm cells, which may contribute to thicker placentas and lower birth weights observed in IVF pregnancies.
Amy Sparks at the University of Iowa called the work a “landmark paper that we will cite for decades to come”. Bartolomei noted that while changing incubators would add some cost, it remains modest compared with overall IVF expenses.
Further safety and efficacy tests in larger animals and humans are still needed before any clinical changes.