Description of How Clomid Induces Ovulation
Clomid is an orally administered drug used to regulate, or stimulate, ovulation. Clomiphene is usually started on cycle day 3, 4, or 5 and continued for five days. The dose varies based upon the cause(s) of the patient’s infertility, previous treatment results, and other factors. The usual starting dose is 50 mg. and if ovulation does not occur the dose can be increased up to 150 mg. per day.
Clomid was originally studied as a birth control pill when researchers discovered its ovulation inducing characteristics. Contrary to follicle stimulating hormone (FSH), which stimulates the ovaries directly, clomiphene's effects are exerted at the hypothalamus.
Clomiphene works by competing, or binding, with estrogen receptors at the hypothalamus. When these receptors are occupied, the hypothalamus “measures” lower estrogen levels and thus releases GnRH, which causes the pituitary to increase FSH production. Increased FSH production leads to enhanced follicular recruitment and development.
It is widely used by obstetrician/gynecologists, often for longer times than recommended. Numerous studies demonstrate that it is most likely to be effective in the first 3-6 ovulatory cycles and pregnancies decline dramatically after 3 cycles. If clomiphene has not worked within this time frame, infertility specialists will usually move to other therapies, such as stimulated (addition of FSH) IUI or IVF.
Our fertility specialists often see patients who have been on clomiphene for as long as a year. Continued use increases the chances of side effects and is expensive. We also see women taking medications whose husbands have not had a semen analysis to rule out male infertility. No fertility drug, will not work unless there are “adequate”, “quality” sperm available. A semen analysis is always recommended before using ovulation enhancing agents.
Older women, or those with declining ovarian reserve, should not "waste" valuable treatment time with clomiphene therapy. Fertility can decrease very rapidly in these women and the most effective treatments should be administered as soon as possible to maximize the chance of having a child. Older women must see an infertility specialist as quickly as possible to insure the most appropriate treatments .
Some infertility specialists are beginning ovulation induction treatment with drugs like Femara (letrozole) Letrozole does not seem to have some of the adverse side-effects seen with Clomid, such as decreased cervical mucus, thinning of the endometrial lining or emotional irritability.
The incidence of twins is 2-3% with the use of Femara compared to 10% with the use of clomiphene. The addition of FSH injections to either of these medications can increase the risk of multiples.
There are epidemiological studies that suggest if clomiphene is used longer then 12 months there may be an increase in the incidence of ovarian tumors. This is a “weak” association but should be considered when prescribing Clomid.
Many fertility specialists monitor clomiphene cycles with ultrasound, which allows visualization of follicular development and documentation of ovulation. Our clinic has the specialized equipment needed to effectively monitor all types of "drug cycles". Our fertility doctors also physically examine patients at regular intervals to check for side effects such as ovarian enlargement.