Progesterone after embryo transfer helps support the pregnancy.
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Assisted reproductive technologies, such as in vitro fertilization, or IVF, and embryo transfer, often help people with infertility problems conceive a child. One of the last steps in the process is placing the embryo into the mother's uterus, where fetal development continues until birth. Fertility specialists commonly recommend that a woman take the female sex hormone progesterone after embryo transfer to help ensure a successful pregnancy.
With in vitro fertilization, eggs are removed from a woman's ovary and exposed to sperm in a culture chamber. Fertilization usually occurs within a few hours, resulting in a microscopic embryo. The embryo grows in an environmentally controlled chamber for 3 to 5 days, with close observation to ensure that development is normal. Once the embryo reaches a certain size, it is ready for transfer into the uterus. This procedure is done in a doctor's office by inserting the embryo via a thin tube, called a catheter, through the woman's vagina and into her uterus. More than one embryo is often transferred to increase the chances of successful implantation into the uterine lining. Any unused embryos are usually frozen under special conditions to ensure their survival for possible use later.
A woman undergoing IVF usually takes sex hormones to stimulate ovulation. Once she ovulates, progesterone supplements are usually recommended to prepare her body for pregnancy. Progesterone is crucial for several aspects of pregnancy. One important function is to prepare the uterus to receive an embryo. Progesterone provokes thickening of the uterine lining, or endometrium, which is the site of embryo implantation. It also stimulates blood vessels and glands in the uterus to enlarge in preparation for pregnancy. Progesterone also affects muscles in the wall of the uterus, helping suppress contractions to keep the womb in a relaxed stated during pregnancy. Later in pregnancy, the hormone helps thicken the muscle but continues to inhibit contractions until just before birth. A woman who has undergone embryo transfer generally uses progesterone for about 2 weeks after the procedure, when a doctor will perform a pregnancy test to determine if one or more embryos has implanted successfully and she has become pregnant.
Using progesterone after embryo transfer increases the likelihood of a successful pregnancy. In a comprehensive review published in 2004 in "Cochrane Database Systematic Reviews," researchers examined the results of 51 studies in which progesterone alone or combined with other hormones was administered after different reproductive techniques, including embryo transfer after IVF. The researchers concluded that use of progesterone after the procedure significantly enhanced the likelihood of a successful pregnancy. The researchers also evaluated different routes of administration, including oral, intramuscular injection and vaginal gel. They reported that oral progesterone was less successful in supporting pregnancy than administering it vaginally or via injection. Based on this and other research reports, use of progesterone after embryo transfer is generally recommended for best results.
The placenta normally begins making progesterone as pregnancy progresses, increasing the rate of production as the fetus grows. The hormone continues to act on the uterus, which expands as the fetus grows. Progesterone also stimulates breast tissue growth to prepare for milk production. After a woman undergoes embryo transfer, the placenta usually produces progesterone in normal amounts, supporting her pregnancy as it proceeds. In most cases, doctors recommend that a woman stop using progesterone between 8 and 12 weeks after the start of pregnancy. Sometimes, however, a doctor may detect low levels of progesterone with a blood test done later in pregnancy. In such cases, continued use of progesterone may be recommended to help support the pregnancy and avoid problems. If you are contemplating a reproductive procedure that might involve embryo transfer or have questions about progesterone use, consult your doctor to discuss the topic and explore the best options for your situation.