PFC Staff to Present Data at the Pacific Coast Reproductive Society Annual Meeting on Benefits of Extending the Culture of Embryos to Day 7

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Culturing embryos to Day 7 expands the pool of available embryos, according to data PFC researchers will present today at the Annual Meeting of the Pacific Coast Reproductive Society.

It’s important to emphasize that freezing (vitrification) technology improves the pregnancy rate with these D7 embryos, said Dr. Chenette.

Today at 6:00 pm at the 2016 Annual Meeting of the Pacific Coast Reproductive Society (PCRS) in Rancho Mirage, CA, Pacific Fertility Center (PFC) staff will present their research findings on pregnancy from embryos that have been cultured to Day 7 (D7).

One of the first to focus on the number of chromosome sets (ploidy) and implantation rate of D7 embryos, the study provides the largest data set available on pregnancy outcomes after transfer of D7 blastocysts (embryos at an early stage of development). This is PFC’s second paper on D7 embryos—and one of only a few in the literature, said senior author, Philip Chenette, MD.

Reviewing embryology records from March 2014 to July 2015, PFC researchers looked only at blastocysts on Day 5, 6, or 7. Of the 5,103 embryos frozen at the blastocyst stage, 816 (16 percent of the total) were frozen on D7 and 53 of these were later transferred to attempt pregnancy.

In the past, embryologists have typically cultured embryos only to Day 6, said Jinnuo Han, PhD, lead author and embryologist in PFC’s laboratory. That’s because D7 embryos—which develop more slowly—are thought more likely to contain an abnormal number of chromosomes (aneuploidy).

“Our D7 embryos were also more likely to be aneuploid,” said Dr. Han. But 33 percent of D7 embryos biopsied and tested with preimplantation genetic screening were found to be chromosomally normal—or euploid.” In fact, healthy D7 embryos had implantation abilities that were comparable to those of D5 and D6 embryos—and produced 22 ongoing pregnancies, 4 percent of the total number. “Although the numbers are small, these D7 embryos should not be overlooked because they may provide patients more opportunities to become pregnant,” said Dr. Han.

It’s important to emphasize that freezing (vitrification) technology improves the pregnancy rate with these D7 embryos, said Dr. Chenette. “There is only one day in the cycle when the uterus is receptive to the embryo, the Window of Implantation. A slow-developing D7 embryo used in a fresh cycle would miss this narrow window. By freezing these embryos and using them in a woman’s future cycle, we can better align timing for successful implantation.”

In addition to Dr. Han and Dr. Chenette, the two other co-authors are Sergio Vaccari, PhD, former PFC embryologist, and Joe Conaghan, PhD, PFC laboratory director.

About Pacific Fertility Center
Pacific Fertility Center is an international destination for male and female fertility treatment and care. It provides an extensive array of fertility treatment options ranging from intrauterine insemination (IUI), intracytoplasmic sperm injection (ICSI) and in vitro fertilization (IVF) to cutting-edge technology such as vitrification and genetic testing of embryos. For more information:


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Renee H. Scudder, MS

Pacific Fertility Center
55 Francisco Street, Fifth Floor
San Francisco, CA 94133

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