Assisted & Conception
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พระราชบัญญัติคุ้มครองเด็กที่เกิดโดยอาศัยเทคโนโลยีช่วยการเจริญพันธุ์ทางการแพทย์ พ.ศ. 2558
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Ovulation induction (OI)

Ovarian stimulation

Ovulation induction (OI) with controlled ovarian stimulation may be recommended for women who have normal tubes, and whose partners have a normal semen analysis, but who rarely or never ovulate. For women who do ovulate regularly, stimulation can also be used to increase the chance of pregnancy by increasing the number of follicles that develop fully and, therefore, increasing the number of eggs that are ovulated during a cycle.

Two types of hormones may be used to stimulate ovulation: tablets of clomiphene citrate (Clomid or Serophene) and injections of follicle stimulating hormone, or FSH (Gonal-F or Puregon).


Clomiphene (Clomid or Serophene) is often the first choice for stimulating ovulation because of its low cost and ease of use. A synthetic hormone, clomiphene acts as an anti-estrogen, tricking the brain into producing higher levels of FSH than in an untreated cycle, which in turn stimulates ovarian follicular development.

A course of tablets is given for 5 days, usually days 2-6 or 5-9 of the cycle. Side effects can include thickening of the cervical mucus, vaginal dryness and hot flushes, while some women also complain of mood changes and irritability. Uncommonly there can be abdominal bloating, breast discomfort, nausea, a skin rash or dizziness. These symptoms usually pass after the 5 days of tablets finish.

Because it is an anti-estrogen, clomiphene can have a negative effect on cervical mucus and on the lining of the uterus, impairing conception and implantation. Pregnancy rates are 5% to 10% per month, or 35% to 40% over a six-month course of treatment.

Follicle stimulating hormone (FSH)

Follicle stimulating hormone (FSH) is the hormone necessary for the multiple follicular development required in IVF. FSH may also be used in smaller doses for ovulation induction or ovarian hyperstimulation. The FSH is made in the laboratory and is identical to human FSH.

FSH is given by injection under the skin, with a fine needle. This is because it is a protein that, if taken orally, would be digested in the stomach.

There are two brands of FSH available in Australia - Gonal-F and Puregon. Both are self-administered with pen-like devices (similar to those used for insulin by diabetics).

Using FSH to induce ovulation for getting pregnant naturally, as opposed to through IVF, can be tricky because of the risk of stimulating too many follicles and having a multiple pregnancy. This is why the body's response is closely monitored with blood tests and ultrasounds.

When the lead follicle or follicles are the right size on ultrasound, ovulation is triggered with an injection of human chorionic gonadotrophin (hCG), which mimics the LH surge. Even with the most careful monitoring, more follicles can reach maturity than desired. Intercourse should be avoided because of the high risk of twins, triplets or an even higher-order multiple pregnancy. If this looks too likely, either the ovulation cycle that has been induced will need to be cancelled or a suggestion might be made to carry out an IVF procedure.

Multiple pregnancy is the single greatest complication in using FSH injections for ovulation induction. If pregnancy occurs, there is a 20% chance of twins. Triplets or higher occur in about 5% of pregnancies. Infertile couples might think twins are a blessing, but complications are much more common in twin than singleton pregnancies.

As it is identical to a hormone that a woman's body makes naturally, the side effects a woman experiences with FSH are really the expected effects of the injections. These include bloating as the ovaries are stimulated and mood changes as estrogen levels rise.

Pregnancy rates depend primarily on the age of the woman, and range from around 10-20% per month, or 40% to 50% over a six-month course of treatment in women under 38.

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