Fertilizacion invitro

The

n e w e ng l a n d j o u r na l

of

m e dic i n e

clinical practice

In Vitro Fertilization
Bradley J. Van Voorhis, M.D.
This Journal feature begins with a case vignettehighlighting a common clinical problem. Evidence supporting various strategies is then presented, followed by a review of formal guidelines, when they exist. The article ends with the author’s clinicalrecommendations.

A 37-year-old woman who has never been pregnant and her 40-year-old husband have been attempting to conceive a child for the past 3 years. An infertility evaluation has shown no cause forthe difficulty. She is ovulating regularly, and a hysterosalpingogram shows that her reproductive tract is anatomically normal. He has a normal sperm count; he has not fathered any children. They arefrustrated and want to proceed with in vitro fertilization. What should you advise?

The Cl inic a l Probl e m
Infertility is common — approximately 10% of couples have difficulty conceiving achild. In young, healthy couples, the probability of conception in one reproductive cycle is typically 20 to 25%, and in 1 year it is approximately 90%.1 An evaluation is commonly recommended after 1 yearof unprotected intercourse without conception, the standard clinical definition of infertility. Many infertility specialists are surprised by the number of otherwise highly educated older coupleswith unrealistic expectations of fertility. The negative effect of a woman’s age on fertility cannot be overemphasized. As women age, fertility declines and the rate of miscarriages increases. Inaddition, the rate of pregnancy after treatment for infertility drops more rapidly in women who are over the age of 35 years than in younger women. Thus, some clinicians argue that an infertility evaluationshould begin after six cycles of unprotected intercourse in women older than 35 years.2 Several societal factors may contribute to infertility related to aging in women. In the United States, there...