When Eggs Near Their Expiration Date
At birth, all females have about 1 million eggs.
By puberty, a woman's egg reserve has declined by 50 percent.
Each month thereafter, she will lose an additional 750 eggs.
Beginning in a woman's 20s, the eggs diminish in quantity and in quality.
Significant deterioration occurs after the age of 35.
When celebrity moms in their late 40s and early 50s show up on the cover of People with their newborns, it's easy to believe anyone can beat the odds and conceive later in life. But what isn't discussed as openly is how much that conception costs - and whose eggs were used.
"Nancy Grace may be having twins at 47, but that's simply not the norm," Dr. Wisot says. Although the Los Angeles-based doctor and author has no particular knowledge of television show host Grace's fertility, he notes, "If a 47-year-old is pregnant with twins, it's either through egg donation or a miracle of Biblical proportions."
Most of us know by now that many factors play into fertility: sperm quality, exposure to chemotherapy, cigarette smoking and stress. But the single most important factor is age. It is, in fact, the primary reason reproductive technology is a thriving business today.
That's because eggs expire. And it doesn't matter how well-maintained the refrigerator is, how expensive the model, or whether it's been running efficiently for 35 or 45 years. Every woman's eggs have an expiration date, and it varies from woman to woman when her carton is depleted.
Maybe your Aunt Judy had a child at 43 and the woman who delivers flowers is expecting at 42. Those cases, says Dr. Ashby, are largely aberrations. There are a small number of women who fall outside the norm for fertility. And for every one of them, there are hundreds the same age who simply cannot get pregnant.
Of course, it's true that it only takes one egg to meet with one sperm to bring us our child. But that stands a much higher chance of happening the younger you are. So first, let's start with the bad news.
Dr. Redmond points to the data to show how eggs decline in quality starting at age 35. Her clinic's pregnancy rates for natural ovulation (no drugs) in various age groups are as follows:
- for women under age 35, it's 18 percent
- age 35 to 37, 10 percent
- age 38 to 40, 8 percent
- and over 40 is 6 percent.
It's not only conception that is affected. The quality of the egg has an impact on the staying power of the embryo as well. The miscarriage rate is:
- 16 percent under the age of 35,
- 32 percent, age 35 to 37,
- 33 percent, age 38 to 40,
- 65 percent, over 40.
The slide in egg quantity and quality begins in a woman's 20s, but really picks up at age 35, increasing rapidly each year up to and beyond age 40. At that age, a woman has only a 5 percent chance or less of becoming pregnant naturally in any one month.
The risk of chromosomal abnormalities in newborns increases to 1 in 66 after the age of 40, compared to 1 in 385 at age 30.
The risk of Down Syndrome increases from 1 in 1,000 at age 20, to 1 in 100 at age 40, according to the Centers for Disease Control in Atlanta.
Now for the good news. Thanks to breakthroughs in technology, there are increasing options for older women.
1. Controlled ovarian hyperstimulation with intrauterine insemination (COH-IUI) increases the chance to conceive in any given cycle. It cannot improve egg or embryo quality. According to Dr. Willman, it involves taking fertility medication fertility medication to increase the number of mature eggs released in a given cycle and the placement of washed sperm into the uterine cavity at the time of ovulation. This treatment has limited success in women 40 and older, with delivery rates of less than 5 percent per cycle.
2. In vitro fertilization (IVF) also increases the chance to conceive without improving the quality of the egg or embryo. It is a useful procedure for women with tubal disease or endometriosis. Pregnancy rates are higher than from COH-IUI but do decline significantly with increasing age. According to 2005 SART data, live birth rates per cycle of IVF were 25 percent in 38- to 40-year-old women, 15 percent in 41- to 42-year-olds, and 5 percent in 43- to 44-year-olds.
Treatment strategies with IVF for older women include more aggressive stimulation protocols, assisted hatching of embryos and replacing more embryos at the time of embryo transfer.
Preimplantation genetic diagnosis may help decrease the rate of miscarriages in older patients by excluding the transfer of genetically abnormal embryos. But this treatment is still being evaluated.
3. Egg donation has become an accepted and successful technique to achieve pregnancy in older women. Studies show that a pregnancy rate of over 50 percent per cycle can be expected in recipients who are aged 40 and older. This treatment is the only treatment available to improve egg/embryo quality in older women.
Egg donation involves preparing the recipient's uterus with estrogen and progesterone to create an optimal uterus for implantation. An egg donor undergoes hormonal stimulation to produce multiple eggs. The eggs are retrieved with a minor surgical procedure and fertilized with sperm. Fertilized embryos are then replaced into the recipient's uterus.
Emotional and financial issues will impact the decision about when, or whether, to move on to egg (oocyte) donation. "If it is important to exhaust any possibility of achieving a pregnancy with your own eggs, then the 44-year-old with a normal Clomiphene Challenge Test may decide that a 3 percent chance is worth taking," says Willman. "In contrast, a 35-year-old with an abnormal FSH level and finances to afford only one attempt with IVF, who is most concerned with being able to have a baby (not the biologic connection), may opt for egg donation."
4. A newer option is egg freezing, also known as oocyte cryopreservation.
While egg freezing has improved, it is still not something every doctor supports. The American Society for Reproductive Medicine recommended against it several years ago. In 2006, however, the group published a report stating that egg freezing has delivered positive results for some women, such as cancer patients.
The freezing of embryos (through IVF) has been accomplished for decades, and at this time has a higher success rate than oocyte cryopreservation. But Christy Jones, founder of the egg-freezing company Extend Fertility, says the rapidly improving technology in egg freezing is influencing the experts' - and the public's - opinion.
In the last several years, two aspects of the freezing process have improved. The freezing of the eggs can now be done without so many potentially harmful ice crystals forming. In addition, breakthroughs have led to the outer membrane of the frozen egg no longer hardening (which used to make it impenetrable to sperm.)
"While egg freezing is still considered investigational by the ASRM, by applying these new advances in cryopreservation, our scientists have realized a sharp increase in post-thaw survival rates and fertilization rates," Jones says. "These improvements have facilitated a dramatic increase in the number of babies born from frozen eggs to over 200 worldwide."
Dr. Licciardi, at NYU, believes the controversial nature of egg freezing is in part rooted in self-interest. "You will find that programs that do not perform egg freezing will tell you it's too experimental and no good. Programs with successful egg freezing experiences [like NYU] will tell you it is an option that women can take if they wish," he says. "It doesn't guarantee a baby, but the bottom line is that it can work."
Dr. Kim, with the University of Chicago, where eggs also are frozen, disagrees. "The problem with egg freezing is it's still considered experimental. Certainly lately it's been more successful, and the technology continues to improve, but it's not like embryo freezing, which has well-established protocols and live birth rates similar to that of regular IVF," she says. "Although our program offers egg freezing for select patients, such as prior to chemotherapy, I don't feel comfortable recommending it routinely at this time. Patients ask 'what if I do it as an insurance policy?' It's possible, but it is a lot of money and there is no guarantee."
Egg freezing can cost upwards of $10,000. It is generally considered most beneficial for women still in their 20s, although Extend Fertility will work with women in their 30s.
