   |  | | What's behind the rise and success of IVF in the United States? | By Mike Magee, MD
Since the beginning of In Vitro Fertilization (IVP) in 1978, IVF babies have been on the rise. One in 50 births in Sweden, one in 60 births in Australia and one in roughly 90 births in the US now occur in parents aided by IVF. In the US each year roughly 100,000 procedures performed in some 400 clinics result in approximately 50,000 babies.1,2
What is IVF? The process involves four basic steps. First, the mother receives medication to stimulate the ovaries to produce eggs. The number and size of the eggs growing toward the surface of the ovary can be monitored by ultrasound. Second, the eggs are retrieved through an ultrasound-guided aspiration needle which reaches the ovary by being placed through the wall of the vagina. Third, the eggs are combined with the father's sperm in a laboratory and fertilized in a culture medium. Finally, the growing embryos are retrieved between 3 and 5 days after fertilization and transferred back into the mother's uterus.1
Before the procedure is considered, mother and father are examined, including blood work, imaging tests, semen analysis and physical examination, and counseling is provided to allow for informed decision-making. The procedure is expensive, invasive and emotionally charged. It is also quite successful compared to other approaches. In 2003, the rate of clinical pregnancy in women undergoing IVF with their own eggs was 34%, with 28% actually achieving a live birth. Success rates are considerably higher in women under 35, with birth rates between 40% and 50%, and considerable lower as mothers age, with only 5% of procedures yielding a live birth at age 43. Live birth rates predictably decline by approximately 5% per year after age 34.3,4
Women are increasingly conscious of the impact of age on fertility.4 Not only does the rate of unaided and aided pregnancy drop progressively, but in addition, rates of miscarriage progressively rise as one ages. As these facts have become more known, and as access to infertility specialists and clinics has expanded, both patients and physician specialists have been less inclined to watch and wait for a natural pregnancy. For example, an increasing number of clinicians believe that an infertility evaluation is more than justified if there has not been a successful pregnancy after 6 cycles of unprotected intercourse in a woman over 35.5
Societal factors will likely increase demand for assistance by women of younger ages in the future. The mean maternal age of first birth has been climbing in the US from 21 in 1968 to 25 in 2002.6 Career and educational goals have been delaying age of first marriage. And more effective contraception has made it more likely that unplanned pregnancies do not occur. Thus the window of opportunity, between decision to become pregnant and maximum capacity to achieve pregnancy with ease has been progressively narrowing. Under such compressed conditions, and with the desire to achieve whatever number of births a couple considers to be the ideal family size, there is little patience for delay in seeking scientific assistance. Finally, the Internet and the health consumer movement support both information and activism. Why "let it happen" when time increasingly makes it likely it will never happen and science is available "to make it happen" now?1
The most common risk associated with IVF is multiple births. While 1% of natural pregnancies result in twins, approximately 1/3 of parents who have live births after IVF have twins.7 Twins from IVF are more common in the US than in many other nations because laws in other countries prohibit implanting more than one embryo at a time. The US has no such laws but increasingly, fertility specialists are voluntarily not implanting more than two embryos at a time.1 But two implants continue to be favored by many US doctors and their patients because they believe this increases the chances of pregnancy and because many parents "prefer twins as a way of attaining their ideal family size quickly". Plus the cost of a cycle of IVF in the US is not insignificant, in the order of $10,000 per cycle.8,9
In other countries, they take a two step approach - implanting a woman's fresh embryo the first month, and trying again with an embryo that has been frozen for one month if the first month fails.1 This strategy is successful 39% of the time and twins appear in less than one percent. In the US, in one study where two embryos were implanted at a time, successful pregnancy occurred in 43% and 33% were twins.10 Twins do have higher rates of pre-term birth and low birth rate. Mothers giving birth to twins require more bed rest, and are more vulnerable to premature labor, hypertension, birth hemorrhage and the Caesarean section delivery. To their credit, most US programs fully inform parents of these issues prior to deciding to proceed with IVF, and parents are often more than happy to make whatever sacrifices are necessary. For now, it is likely that both rates of IVP births and rates of twin births in the US will continue to rise side by side.1
References
1. Van Voorhis BJ. In Vitro Fertilization. NEJM, 356:4, January 25,2007. 379-385.
2. Steptoe PC, Edwards RG. Birth after the reimplantation of a human embryo. Lancet 1978;2:366-366.
3. CDC Website.
4. 2003 Assisted reproductive technology (ART) report. Atlanta: Centers for Disease Control and Prevention, 2003. Accessed December 15, 2006.
5. Gnoth C, Godehardt E, Frank-Herrmann P, Friol K, Tigges J, Freundl G. Definition and prevalence of subfertility and infertility. Hum Reprod 2005;20:1144-1147.
6. Hamilton BE, Ventura SJ. Fertility and abortion rates in the United States, 1960-2002. Int J Androl 2006;29:34-45.
7. Russell RB, Petrini JR, Damus K, Mattison DR, Schwarz RH. The changing epidemiology of multiple births in the United States. Obstet Gynecol 2003;101:129-135.
8. Wenstrom KD, Syrop CH, Hammitt DG, Van Voorhis BJ. Increased risk of monozygotic twinning associated with assisted reproduction. Fertil Steril 1993;60:510-514.
9. Jain T, Harlow B, Hornstein MD. Insurance coverage and outcomes of in vitro fertilization. N Engl J Med 2002;347:661-666.
10. Thurin A, Hausken J, Hillensjö T, et al. Elective single-embryo transfer versus double-embryo transfer in in vitro fertilization. N Engl J Med 2004;351:2392-2402. | | |
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