Ovulation induction
The term ovulation induction can potentially also be used for: However, this article focuses on medical ovarian stimulation, during early to mid-follicular phase, without subsequent in vitro fertilization, with the aim of developing one or two ovulatory follicles (the maximum number before recommending sexual abstinence).
It is a selective estrogen-receptor modulator, affecting the hypothalamic–pituitary–gonadal axis to respond as if there was an estrogen deficit in the body, in effect increasing the production of follicle-stimulating hormone.
[11] It also has an effect on cervical mucus quality and uterine mucosa, which might affect sperm penetration and survival, hence its early administration during the menstrual cycle.
This difference may be due to the anti-estrogenic effect which clomifene citrate has on the endometrium, cervical mucus, uterine blood flow, as well as the resulting decrease in the motility of the fallopian tubes and the maturation of the oocytes.
The urinary preparations are equally effective and less expensive, but are not as convenient to administer as they are available in vials versus injection pens.
It can also provide presumptive evidence of ovulation such as sudden collapse of the preovulatory follicle, and an increase in fluid volume in the rectouterine pouch.
[26][8] In cancelled cycles, the woman or couple should be warned of the risks in case of supernumerary follicles, and should avoid sexual intercourse or use contraception until the next menstruation.
[26] Alternatives to cancelling a cycle are mainly: The following laboratory tests may be used to monitor induced cycles:[28] Final maturation induction and release, such as by human chorionic gonadotropin (HCG or hCG) or recombinant luteinizing hormone, results in a predictable time of ovulation, with the interval from drug administration to ovulation depending on the type of drug.
[4] As evidenced by clomifene-induced cycles, however, triggering oocyte release has been shown to decrease pregnancy chances compared to frequent monitoring with LH surge tests.
[28] Therefore, in such cases, triggering oocyte release is best reserved for women who require intrauterine insemination and in whom luteinizing hormone monitoring proves difficult or unreliable.
[31][32] In women with anovulation, 7–12 attempted cycles of pituitary feedback regimens (as evidenced by clomifene citrate) are recommended before switching to gonadotrophins, since the latter ones are more expensive and less easy to control.
[33] Symptoms depend on whether the case is mild, moderate, or severe, and can range from bloating and nausea, through to shortness of breathe, pleural effusion, and excessive weight gain (more than 2 pounds per day).
Multiple pregnancy occurs in approximately 15–20% of cases following cycles induced with gonadotrophins such as human menopausal gonadotropin and follicle-stimulating hormone.
