The egg and ice (as in cold)
Next week, the American Society for Reproductive Medicine plans to announce a big change: It will no longer consider the freezing of women’s eggs to treat infertility as “experimental.”
The practice of freezing eggs for future in vitro fertilization (IVF) efforts has long been controversial, with many experts arguing that there was insufficient data about its safety or efficacy. The approach was typically recommended only when a woman had few or no other options. Example: Someone facing chemotherapy treatments who wanted to preserve some of her eggs so that she could have children later.
But a new report by the Society for Assisted Reproductive Technology Practice Committee, which reviewed nearly 1,000 studies, has concluded that egg-freezing and thawing techniques have much advanced, making the process closer to routine.
That’s good news for women seeking IVF treatments, more and more of whom are using frozen eggs because they are older (in which case they may rely upon a frozen egg from a donor) or they are younger (and want to focus on their education or career, with family coming much later).
The policy change is not without caveats. The ASRM cautions against doctors or clinics aggressively promoting egg-freezing as a guaranteed way to preserve the future option of pregnancy. Not enough studies have been done yet to assess how well long-term egg-freezing works. And other groups note that the new policy is based upon data about pregnancies, not healthy births.
“Women who are considering doing this for elective reasons should understand that they are really at the leading edge of using this technology,” Eric Widra, an infertility doctor and chair of the SART committee told NPR. “We’re not yet certain that it will provide the promise that we hope it does.”
There’s a popular science factoid that says every human spends about half an hour as single cell. But no human egg is ever really alone. In the above image, produced by English microscopist Spike Walker, an oocyte (orange) is released from the ovary. It is surrounded by two structures: a matrix of glycoproteins called the zona pellucida (brown rim) and a layer of follicler cells called the corona radiata (yellow). Human fertilization begins when the sperm finds its way through the corona radiata and binds to a sugar group in the zona pellucida.
In this particular image, depicting an IVF attempt, the effort fails; none of the sperm penetrate the corona radiata.