Assisted reproductive techniques (ARTs) involve manipulation of sperm and ova in vitro with the goal of producing an embryo.
ARTs may result in multifetal pregnancy, but risk is much less than that with controlled ovarian hyperstimulation. If risk of genetic defects is high, the embryo can often be tested for defects before transfer and implantation (preimplantation genetic diagnosis).
In women < 35, > 47% of ART cycles result in pregnancy, and 87% of the pregnancies end in live births in the US (2010 data). The pregnancy rate decreases with increasing age; for women aged 41 to 42, the pregnancy rate is about 20%, and only about 62% of these pregnancies end in live births. Use of donor oocytes is usually recommended for women > 42.
In vitro fertilization (IVF)
IVF can be used to treat infertility due to oligospermia, sperm antibodies, tubal dysfunction, or endometriosis as well as unexplained infertility. The procedure involves the following:
Birth defects may be more common after IVF, but experts are uncertain whether the increased risk is due to IVF or to factors contributing to infertility; infertility itself increases risk of birth defects. Still, as of mid-2012, the overwhelming majority of the > 5 million children born after IVF have no birth defects.
Gamete intrafallopian tube transfer (GIFT)
GIFT is an alternative to IVF but is used infrequently, typically for women with unexplained infertility or with normal tubal function plus endometriosis. Multiple oocytes and sperm are obtained as for IVF but are transferred—transvaginally with ultrasound guidance or laparoscopically—to the distal fallopian tubes, where fertilization occurs. Live birth rates per cycle are about 25 to 35% at most infertility centers.
Intracytoplasmic sperm injection
This technique is useful when other techniques are not successful or are unlikely to be so or when a severe sperm disorder is present. Oocytes are obtained as for IVF. A single sperm is injected into each oocyte to avoid fertilization by abnormal sperm. The embryo is then cultured and transferred as for IVF. In 2010, about two thirds of all ART cycles in the US involved intracytoplasmic sperm injection. Risk of birth defects may be increased after intracytoplasmic sperm injection, possibly because the procedure itself can damage the sperm, egg, or embryo or because sperm from men who have mutations of the Y chromosome are used. Most reported birth defects involve the male reproductive tract.
A combination of IVF and GIFT, zygote intrafallopian tube transfer, use of donor oocytes, and transfer of frozen embryos to a surrogate mother are sometimes used. Some of these techniques raise moral and ethical issues (eg, rightful parentage in surrogate motherhood, selective reduction of the number of implanted embryos if multifetal pregnancy results).
Last full review/revision January 2013 by Robert W. Rebar, MD