Clomid & Other Fertility Drugs

Clomid & Other Fertility Drugs

When are Fertility Drugs Used?

Women start life with a finite amount of eggs (about 1 million at birth.) Every few weeks, a group of these eggs begin to grow; if their growth coincides with the start of a menstrual cycle, the eggs get to “compete” to ovulate. The “dominant” egg is selected for ovulation through communication between the brain (the pituitary gland) and the ovaries. The brain releases FSH and LH; the ovary answers back with Estradiol and Progesterone.

Fertility drugs take advantage of this communication loop, to induce ovulation in women who do not ovulate, or to induce “super-ovulation” (release of 2+ eggs per month) in women who are already ovulating on their own.

What is Clomid (clomiphene citrate)?

Clomid is a serum estrogen receptor modulator (SERM), meaning that Clomid binds to receptors that normally hold estrogen and Clomid blocks the effects of estrogen. The brain thinks estrogen levels are low and that the ovaries are being lazy, so the pituitary gland releases more FSH and LH, which stimulates egg growth. This can induce ovulation in women who do not ovulate, or induce “super-ovulation” in women who are already ovulating on their own.

Clomid is an oral pill, usually taken for 5 days in a row. The side effects of Clomid come from the low estrogen effects: hot flashes, headaches, moodiness, vaginal dryness. The uterine lining can be thinner than normal because it also depends on estrogen to grow – this should be monitored during treatment. The risk of twins on Clomid is ~ 8%/cycle; the baseline risk of twins in the general population is 2-3%. The risk of triplets is < 1%.

Tamoxifen is another serum estrogen receptor modulator (SERM) that works in a similar way

Other Fertility Drugs

Letrozole/Femara
Letrozole is an aromatase inhibitor. Aromatase usually converts androgens (male hormones) to estrogens. When Letrozole blocks aromatase, the level of estrogen in the body truly goes down. The brain senses low estrogen levels and, again, assumes the ovaries are being lazy, so the pituitary gland releases more FSH and LH, which stimulates egg growth. This can induce ovulation in women who do not ovulate, or induce “super-ovulation” in women who are already ovulating on their own.

Letrozole is an oral pill, usually taken for 5 days in a row. The side effects of Letrozole are similar to Clomid, but often milder (because the estrogen block is not complete.) The risk of twins and higher order multiples (triplets+) is similar to Clomid.

Gonadotropins (FSH/LH)
Trade names include Follistim, Gonal-F, Menopur, HMG. These are injectable medicines that mimic pituitary gland FSH/LH and directly stimulate egg growth. They typically induce more eggs/follicles to grow than the oral medicines (Clomid and Letrozole). They are often used in an in vitro fertilization (IVF) cycle. Side effects include local injection site reactions and ovarian hyperstimulation.

HCG – Ovidrel, Novarel, Pregnyl
This is an injectable medicine that mimics pituitary gland LH to stimulate egg ovulation. Side effects include local injection site reactions and ovarian hyperstimulation.

 

If you have questions about Clomid and other fertility drugs, give us a call at 678.841.1089 to schedule a consultation with one of fertility specialists.

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