Thirty nine years ago, Lesley and John Brown began their quest to try and start a family. For nine long years they tried repeatedly, and had failed at their attempts to have children. Lesley discovered that her fallopian tubes were blocked and would not allow an egg to travel from its location in the ovary to near the opening of the tube so that fertilization could occur.
Steptoe and Edwards, a gynecologist and physiologist, respectively, had been working on a new technique that would help women who had been previously unable to conceive to potentially have children. Before this venture, Steptoe had made his mark as one of the pioneers of laparoscopy, which is a commonplace procedure these days that has revolutionized how many surgeries are performed. Edwards had developed an appropriate culture medium for embryos to grow in, and as a reproductive physiologist had achieved what no one thought was possible--in vitro fertilization of a human egg. Using laparoscopy, Steptoe was able to retrieve eggs from the ovaries of infertile women, fertilize them in a petri dish and then implant them into the uterus.
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After nearly a decade of failure to conceive, in the fall of 1976, Lesley Brown and her husband agreed to try the experimental in vitro procedure. They had been referred to Steptoe through their infertility specialist. Steptoe explained the procedure carefully, but left out one crucial detail--that at that point in time, the procedure had not resulted in a successful pregnancy. The Browns agreed to try the procedure, and in the fall of 1977, Lesley Brown underwent the world's first in vitro fertilization treatment.
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Nine months later on July 25, 1978, Louise Brown was born, and never has the conception and birth of a single human being been both heralded and criticized as hers was. Many misunderstood the entire in vitro procedure and believed that Brown was born in a laboratory. Some thought that because her conception was not natural, she would end up deformed or disabled in some way. Others saw her conception as hope that their infertility woes could be cured and that they too could welcome a child of their own into the world.
In vitro fertilization (IVF) requires that the mother be given fertility drugs to stimulate her ovaries to release more eggs than they usually would in a normal menstrual cycle. Because so many eggs are released, many of them are fertilized and implanted to increase the chances that the embryos will implant on the uterine wall and the mother will carry them to term.
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The issue at hand is the incidence of multiple births. It is widely known that IVF pregnancies yield a higher percentage of multiple births than babies conceived naturally. The trend in the last decade or so, however, has been for mothers to give birth to not twins or triplets, but quintuplets, sextuplets or even septuplets. Many times, the babies born in these multiple births come into the world prematurely, and with a multitude of medical problems, some of which result in permanently disabling conditions such as cerebral palsy (as one of the McCaughey septuplets is stricken with).
Doctors now are calling for implantation of fewer embryos to reduce the risk of delivering multiple babies prematurely. Reproductive technology has improved drastically in the past few years, and now doctors can insert an individual sperm cell into a single egg during a procedure known as ICSI (shown at left). This insures that fertilization takes place, but does not insure implantation. Regardless, technologies used to help couples conceive have improved drastically. Sometimes, when a couple undergoes IVF and multiple embryos result, the couple is asked if they wish to selectively reduce the number of fetuses in order to improve the health of the other fetuses as well as the mother.
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Here's the part of the post you've been waiting for: which issue presents more of a dilemma--risking birthing multiple babies with health issues, some of which may be debilitating, or choosing to select certain fetuses for elimination in order to benefit the greater good (in this case, mom and remaining fetuses)? Do you think that couples will continue to have what technically amounts to litters of children? Is this a responsible thing to do? How does IVF interrupt nature's built in mechanisms for evolution?
Think about what you know about multiple births, natural selection and evolution before you respond.
Posted by scienceguru on February 28, 2008
Tags better living through biological science, bioethics, dilemmas dilemmas!, discuss, reproduction
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