March 15, 2010

Questions for the Stork

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Women’s biological clocks start ticking before birth, causing a decline in their ovarian reserve of eggs. According to a recent Scottish study, women lose 88 percent of their eggs by age 30, and by age 40, only three percent of their eggs remain. Should college girls be paying more attention to this declining fertility while making their life plans? Or can technology provide enough options for women at later ages?

Prof. Andrea Parrot, policy analysis and management, studies policy relating to women’s health, human sexuality and ethics. She noted that issues of biology, technology, class and individual values all play into the decision to have children. Biologically, fertility does decline with age, especially after the mid-30s.

“If a woman’s priority is to become the next great neurologist, putting off childbearing may make sense,” Parrot said. “However, it is not a good idea to put it off until you are 45.”

Scottish scientists published the first report ever, analyzing the female egg supply from conception to menopause. The scientists developed a computer model based on a study of 350 women of various ages in the U.K., Europe and the United States. The researchers hope that their findings may yield tests that will inform women of their ovarian reserve, allowing both older women and women with ovarian cancer to choose either to become pregnant or to freeze eggs.

According to the study, women on average are born with 300,000 egg cells. This number, however, varies from woman to woman, and can range from two million to only 35,000. A woman’s egg supply is highest about 20 weeks after conception, while she still resides in the womb. The ovaries contain follicles, in which each egg starts to grow to maturity. In order to mature, the eggs need hormonal stimulation. Prior to puberty, hormones are too weak to foster maturation, so many eggs die off.

After puberty, about 1000 eggs begin to mature during each menstrual cycle. However, during typical ovulation, only one follicle releases an egg per cycle. This egg travels down the fallopian tube to the uterus, where fertilization can occur within 24 hours or the egg will disintegrate and leave the body through menstrual bleeding. Then, a new cycle of egg maturation begins. This process continues until all the eggs are depleted at menopause, typically around age 51.

Not only does the size of the ovarian reserve decrease, but the quality of the eggs also declines, according to the Scottish study. As the mother ages, this change in egg quality causes frequent miscarriages and infant health problems.

Parrot noted that technology to freeze embryos can preserve the ability to give birth for many years, offering new options to the current generation of women. Several types of assisted reproductive technology (ART) include in vitro fertilization, tubal embryo transfer, the transfer of eggs and sperm into a woman’s fallopian tube and sperm injection. These procedures may involve the use of donor eggs, donor sperm or previously frozen embryos. The frozen embryos can come from the couples or from donations.

According to the Centers for Disease Control, ART babies are two to four times as likely to have birth defects, such as heart and digestive system problems and cleft lips and palates. Researchers have not yet determined the reason for this, but it could relate to the age of the parents.

Other complications can arise during divorces, in which, disagreements emerge about the future of a frozen embryo.

Parrot stated that the implantation of embryos into surrogate mothers can raise ethical issues.

The most likely surrogate mothers include poor women, she noted. “What would be the ethics of flying to India and paying one-tenth the price for a surrogate?”

Danielle Bergstrom, grad, city and regional planning, stated that college-age women are generally aware of the issue of declining fertility with age. “It’s definitely something that we think about, but we don’t talk to each other about it that much,” she said. While not familiar with the new study, Bergstrom stated that reconciling career decisions with the desire for a family remains an issue despite advances in technology.

According to Parrot, women should inform themselves about the biology, and then, examine their own ethics and priorities.

Original Author: Rachel Bensinger