Fertility medications for intrauterine insemination in women with decreased ovarian reserve

This study compared fertility medications for intrauterine insemination (IUI) for women with diminished ovarian reserve (DOR). It found that letrozole (Femara) and clomiphene citrate (Clomid) tablets gave similar results to injected gonadotropins (Gonal-F).

DOR is a condition in which few ovarian follicles (which contain the eggs) develop each month. DOR occurs more frequently for women in their late 30s and 40s. The condition can make it more difficult to achieve a pregnancy. A common infertility treatment uses ovarian stimulation (OS) medications to develop multiple mature ovarian follicles. OS is often combined with IUI, in which sperm is injected directly into the uterus. Patients with DOR produce fewer follicles in response to OS.

Several medications can be used for OS. Gonadotropins are a synthetic version of the hormones which naturally stimulate the ovaries. While effective, gonadotropins also have a risk of complications including over-stimulating the ovaries. There is a risk of multiple pregnancies (twins or triplets), which is more dangerous for both the mother and babies. Additionally, gonadotropins are administered by injection and require close monitoring. This increases the cost and discomfort of OS treatment.

Letrozole and CC are pills used for OS. Both medications interfere with how the hormone estrogen works, causing the body to create its own gonadotropins. These oral OS medications are gentler on the body than direct gonadotropins and have fewer side effects and lower cost.

There is less research comparing these three forms of OS with IUI for patients with DOR.

This study used records from 210 women undergoing 335 cycles of IUI with OS. All of the patients were between ages 38 and 43 and had DOR. In this study, DOR was defined as few follicles visible on ultrasound at the start of the menstrual cycle (6 or fewer). Most of the cycles used gonadotropins (264). A smaller number used CC (38) or letrozole (33). The three groups had similar ages and tests of ovarian reserve. When one of the ovarian follicles was mature, ovulation was triggered using the hormone hCG and the IUI was done.

The three medications led to similar pregnancy rates. The pregnancy rates per cycle were 5.3% with CC, 9.1% with letrozole, and 7.5% for gonadotropins.

This study found that oral OS drugs led to similar pregnancy rates as gonadotropins for patients with DOR using IUI.

Letrozole cycles had a higher pregnancy rate on ultrasound than cycles with gonadotropins (9.1% vs. 7.5%). However, random chance could cause this difference, because this study had few participants taking letrozole.