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Progesterone Supplements after IUI (Intrauterine Insemination)

Progesterone supplements after an intrauterine insemination (IUI) at a glance

  • Progesterone supplements are a form of natural progesterone used after an intrauterine insemination (IUI) to help promote pregnancy.
  • Progesterone is a natural hormone made by the ovaries necessary for the uterus to prepare for and maintain a pregnancy.
  • Progesterone supplements after an IUI can improve the receptivity of the uterine lining, enhancing the chances of implantation of a fertilized egg.
  • The side effects of progesterone supplements may resemble the symptoms of pregnancy.

What are progesterone supplements?

Progesterone is a hormone naturally produced by the ovaries after an ovarian follicle releases an egg (ovulation). Progesterone supplements are hormone medications prescribed by a physician that match the composition of the progesterone hormone made by the ovaries. They are given to women for a variety of reasons, some of which include:

  1. Women who have problems making progesterone
  2. Women undergoing IUI
  3. Women going through in vitro fertilization (IVF)

Progesterone helps transition the endometrial lining into a receptive phase, allowing a chance for the fertilized egg to implant into the uterine wall. Progesterone supplementation further supports an early developing pregnancy until the placenta is making sufficient level of the progesterone hormone, which usually occurs between the 7th and 9th week of pregnancy.

After a natural fertilization, the oocyte separates from the follicle, which then produces progesterone as a signal to the uterus to maintain the uterine lining for implantation. Progesterone also signals the body to stop menses and preserve the pregnancy.

The supplements can be taken in various ways, including vaginal gels, vaginal suppositories, vaginal inserts, oral capsules and injections.

Why take a progesterone supplement after IUI?

With an intrauterine insemination attempt, taking a progesterone supplement may help promote pregnancy by enhancing the signal to the uterus to transition into a receptive phase for the embryo, and by mimicking the signal that stops menses and allows the pregnancy to develop. Progesterone supplements after an IUI can prolong the lifespan of the uterine lining, giving an egg more time to become fertilized and implant.

Like many hormones, progesterone has a wide range of effects in the body, and not all of them are fully known. Scientific evidence suggests that progesterone taken after IUI may promote pregnancy.

Intrauterine insemination is a procedure where sperm is washed, concentrated and placed directly into the uterus. The sperm preparation process also helps the sperm activate, which means they are more likely to bind to the egg once they reach the egg(s). With IUI, sperm bypasses the cervix because it is placed directly into the uterine cavity, giving the sperm much greater chances of reaching and fertilizing the egg. IUI is often done in conjunction with fertility medications.

Which route of administration is best?

After IUI, vaginal administration tends to achieve the highest tissue levels (endometrial levels) of progesterone. For this reason, most doctors prescribe vaginal tablets or suppositories after IUIs. Progesterone can be taken orally, however, there are typically more side effects and there may not be quite as high levels of prgesterone achieved in the uterus as with vaginal application methods.

After IVF cycles, progesterone is given vaginally or by injection (intramuscularly). Either route is equally effective and the medication and method chosen are typically decisions made by the physician or jointly by the physician and patient.

Risks & side effects of progesterone supplements

Because progesterone affects the body in several ways, there can be a lot of side effects associated with supplement use:

Breast tenderness

As with a natural pregnancy, progesterone causes the breasts to prepare for breastfeeding. This causes the mammary glands to grow, and the breasts to swell as a result.

Gastrointestinal distress

High levels of progesterone may induce nausea, vomiting, constipation and bloating.

Mental effects

Progesterone can bind to receptors in the brain, causing some psychological effects. Mood-swings, headaches and excessive sleep are common side effects. Progesterone may also have a sedating effect.

Skin reactions

When taking progesterone by injection, skin reactions are common, such as rashes, bumps and redness at the site of injection. Also, because the injection has to be done through the buttocks and this requires a long needle, there is often associated pain.


Vaginal suppositories and gels can both have associated leakage and discharge. Both of these can by very messy and require frequent cleaning.