Women’s Health Care Resources

Infertility Services

Ovulation Induction Medications

About 25% of women struggling with infertility have problems with ovulation. These challenges can include the inability to produce a fully mature egg or failure to release a mature egg from the ovary. Subtle or obvious hormonal imbalances can interfere with the normal development, maturation, and fertilization of an egg.

Certain conditions can affect ovulation leading to infertility including polycystic ovarian syndrome (PCOS), thyroid disease or other hormonal disorders. Women who are overweight or significantly underweight are also less likely to ovulate consistently than women of a normal body weight. Sometimes the cause of ovulatory dysfunction cannot be concretely identified.

Women with ovulatory dysfunction typically benefit from ovulation induction with fertility medications. These medications can help a woman to ovulate more regularly or allow for multiple eggs to develop and be released at one time. Ovulation induction medications work by either lowering estrogen levels or by making the brain think they are low. Low estrogen levels tell the pituitary gland to produce more FSH, which helps a follicle to grow and release an egg.

The most common risk in using these medications is multiple pregnancy. The chance of twins on oral OI medications is 5%-8% and the chance of triplets is less than 1%. Ovarian cysts may occur although it is uncommon for these cysts to require any treatment. In women who do not ovulate on their own, about 80% of women who use these medications over several months will ovulate.

Ovulation Induction Therapy & Hormones

There are several options for fertility medications that can aid in correcting ovulatory dysfunction thereby increasing the chance for pregnancy.

  • Clomiphene Citrate (also known as Clomid): This medication is taken orally for five days each cycle, usually days 3-7. Clomiphene is similar to the estrogen molecule and works by blocking estrogen receptors in the brain. This essentially “tricks” the brain into thinking that your ovaries aren’t working well and drives them to work harder by enlarging the follicles and producing more estrogen. When the brain sees a high enough “trigger level” of estrogen from the ovary, it will finally send out enough of the ovulation signaling hormone, LH, to rupture the most promising follicle(s) and release the egg. The lowest effective dose of clomiphene is used for at least 4-6 cycles to provide an adequate trial. Common side effects may include hot flashes, night sweats, mood changes, vaginal dryness, fatigue and nausea. They are usually limited to the short duration you are taking the medication. 
  • Letrozole (Femara): When used early in the menstrual cycle, letrozole inhibits the production of estrogen. This results in normal or enhanced follicular recruitment without the risk of ovarian hyperstimulation. Letrozole has a very short half-life (~45 hours) and, therefore, is quickly cleared from the body. For this reason, it is less likely to adversely affect the endometrial lining and cervical mucus. Because of this as well as its increased tolerability, letrozole has become our initial treatment choice over Clomid. Letrozole is superior for ovulation induction in patients with polycystic ovarian syndrome (PCOS). The lowest effective dose of letrozole is used for at least 4-6 cycles to provide an adequate trial. Common side effects may include hot flashes, night sweats, mood changes, vaginal dryness, fatigue and nausea. They are usually limited to the short duration you are taking the medication. 
  • Metformin: Commonly used in true polycystic ovarian syndrome (PCOS), this medication is thought to increase the sensitivity and number of insulin receptors throughout the body (especially the ovary). This thereby allows cells to make glucose more available and promotes better cellular metabolism & function. This medication may help you to ovulate more regularly.
  • HCG Trigger (Human Chorionic Gonadotropin, Pregnyl): This injectable medication is naturally harvested and purified from the urine of pregnant mothers. This hormone is produced by the embryo and its placental tissues to give a signal to the ovary to continue to produce progesterone long after the ovary should have stopped producing it in a routine cycle. It is also a hormone whose structure resembles LH. Because of this, we frequently will use this medication to mimic the work of LH to promote ovulation. This helps improve the timing for successful fertilization after intercourse.

We often monitor ovulatory function with over-the-counter OPKs (ovulation predictor kits) which are easy and relatively inexpensive urine tests that can be done at home. We also monitor medicated cycles with midcycle ultrasounds done in the office.

Monitoring for Medicated Cycles

A midcycle ultrasound is performed during a medicated cycle to determine if and how many mature follicles are present during your cycle. Follicles are small sacs of fluid found on the outside layer of the ovaries, which contain immature eggs (oocytes). When the time comes and the follicle has grown to the appropriate size, it ruptures and releases a mature egg ready to be fertilized. During this ultrasound, we want to ensure you have at least one dominant follicle that will ovulate for the cycle but not more than two which would increase the chance for a multiple pregnancy. During a midcycle scan, we will also look at the uterine lining to ensure it is thickening appropriately.

Monitoring Schedule

  • We will perform a mid-cycle ultrasound on cycle day 12 (can be adjusted on an individual basis depending on cycle length).
  • If cycle day 12 (CD12) falls on a Saturday or Sunday, you will need to come in on Friday.
  • If CD12 falls on a holiday, we will do your ultrasound on CD13.
  • Depending on what we see on your midcycle ultrasound (follicle size, etc.), you may need to come back in 2 -3 days for a repeat ultrasound.

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