While many people have babies after in vitro fertilization (IVF), success depends on many different things. Almost all assisted reproductive technology (ART) procedures are done using IVF.

Age.

Birth rates resulting from a single cycle of IVF using a woman's own eggs are about 30% to 40% for women age 34 and younger, then rates decrease steadily after age 35.^{footnote 1} The aging of the egg supply has a powerful effect on the chances that an assisted reproductive technology (ART) procedure will result in pregnancy and a healthy baby.

Cause of infertility.

Infertility can be caused by problems with the reproductive system. Some of these causes can include problems with the fallopian tubes, with ovulation, or with the sperm.

Pregnancy history.

A woman who has already had a live birth is more likely to have a successful ART procedure than a woman who hasn't given birth before. This "previous birth advantage" gradually narrows as women age from their early 30s to their 40s.

Own eggs versus donor eggs.

Birth rates are affected by whether ART procedures use a woman's own eggs or donor eggs. Many women over age 40 choose to use donor eggs, which greatly improves their chances of giving birth to healthy babies. For each cycle of in vitro fertilization:^{footnote 1}

• Using her own eggs, a woman's chances of having a live birth decline from around 35% in her late 20s, to around 20% at about age 38, and to 4% by about age 43.
• Live birth rates are about the same among younger and older women using donor eggs. Women in their late 20s through mid-40s average about a 55% birth rate using fresh (not frozen) embryos.

Frozen embryos versus fresh embryos.

Donor-frozen IVF embryos from a previous IVF cycle that are thawed and transferred to the uterus are less likely to result in a live birth than are donor-fresh (newly fertilized) IVF embryos. But frozen embryos are less expensive and less invasive for a woman, because superovulation and egg retrieval aren't needed.

In vitro fertilization (IVF) increases the risks of ovarian hyperstimulation syndrome and multiple pregnancy.

• Superovulation with hormone treatment can cause severe ovarian hyperstimulation syndrome. Your doctor can reduce this risk by closely monitoring your ovaries and hormone levels during treatment.
• The risk of a multiple pregnancy is directly related to the number of embryos transferred to the uterus. Multiple pregnancies are high-risk for both the mother and the fetuses.

There may be a higher risk of birth defects for babies conceived by certain assisted reproductive techniques, such as IVF. Talk with your doctor about these possible risks.

Embryo transfer success versus the risk of multiple pregnancy

For a woman over age 35 to have the best chance of conceiving with her own eggs and carrying a healthy pregnancy, she may choose to have more embryos transferred than a younger woman would. But this increases her risk of multiple pregnancy.

Because of the risks to the babies of multiple pregnancy, experts recommend limiting the number of embryos transferred. Your doctor will recommend a certain number of embryos to be transferred based on your age and specific situation.

Women over 40 have a high rate of embryo loss when using their own eggs. Instead, older women can choose to use more viable donor eggs. If you're using donor eggs, the number of embryos you receive will be based on the age of your donor.