In vitro fertilization is now a reliable albeit pricey path to pregnancy for younger women struggling to have children, but it remains a longer shot once women reach their late 30s.
The Center for Reproductive Medicine in Minneapolis reported births for 62 percent of women 35 and younger using fresh nondonor embryos for IVF in 2013, for example. But that rate dropped to 37 percent for women 38 to 40.
IVF clinics now are trying to close that age disparity by increasing access to preimplantation genetic screening — a method of evaluating embryos to determine if they are missing chromosomes before implanting them in infertile women.
And at least one clinic has data to show it is working.
The Colorado Center for Reproductive Medicine (CCRM), which opened an Edina branch this summer, examined 1,000 IVF cases in which a single embryo was transferred into a woman.
Screening embryos and only using those with complete chromosomes — the cellular threads that carry genetic information — resulted in a pregnancy rate for older patients that was comparable to the rate for younger patients, the data showed. Miscarriages and birth complications declined, as well.
“We can level the playing field, enabling older women to experience the same success as younger women,” said Dr. April Batcheller, who founded CCRM’s Edina clinic.
Screening involves a biopsy of a blastocyst, an embryo at 5 days old. It has risks. Embryos must be frozen while awaiting the results, and a few don’t survive that process.
Screening also costs thousands and lengthens IVF, so it isn’t recommended for younger women, whose odds with IVF are already favorable.
It made sense for 39-year-old Leah Tototzintle, though. Doctors told the mortgage specialist to only transfer one embryo in her IVF attempt due to other health problems. (Using more embryos improves the odds of pregnancy, but also of risky multiple births.)
Doctors retrieved 27 of her embryos. Eight matured into blastocysts, but screening found only one with all 23 pairs of chromosomes.
It was mixed news. If Tototzintle doesn’t get pregnant next month when the healthy embryo is transferred, she won’t have others readily available. But the important thing was finding the embryo that gives her and her husband the best chance, she said. “We are cautiously optimistic.”