Many fertility drugs increase a woman's chance of having twins, triplets or other multiples. Women who are pregnant with multiple fetuses have more problems during pregnancy. Multiple fetuses have a high risk of being born too early (prematurely). Premature babies are at a higher risk of health and developmental problems. Only 15 percent of infertile American women have tried fertility drugs and only one percent has tried IVF.

• Aspirin: Aspirin is prescribed to all patients after egg retrieval. It acts as a blood thinner, increasing the blood supply to the lining of the uterus where implantation is to occur.

• Bromocriptine (Parlodel): This medicine is used for women with ovulation problems due to high levels of prolactin. Prolactin is a hormone that causes milk production.

• Clomiphene Citrate (Clomid): This medicine causes ovulation by acting on the pituitary gland. It is often used in women who have PCOS or other problems with ovulation. This medicine is taken by mouth.

• Estrogen: Estrogen may be administered late in the IVF cycle, usually by skin patches, in order to support the development of the embryo and stabilize the uterine lining.

• Follistim and Gonal-F: FSH works much like hMG. It causes the ovaries to begin the process of ovulation. This is used to control ovarian hyperstimulation. This process causes the production of several eggs that will be harvested for the in vitro fertilization process. Ultrasound and estradiol measurements are used to monitor the development of the follicles. Patients must visit their clinic’s office several times during their stimulation for these tests. When the follicles measure 18 mm in mean diameter, and the estradiol levels are appropriate, ovulation is triggered by the use of recombinant Ovidrel (recombinant LH) or hCG. These common fertility drugs that are administered for approximately 10 days commencing on day two or three of the patient's cycle. The particular drug and dosage varies between patients depending on the patient's age, weight, and previous response to fertility drugs. Other gonadotropins containing both FSH and LH include Repronex, Bravelle, and Menopur. These may also be used to promote egg development.

• Ganirelix, Cetrotide: These drugs are GnRH Ganirelixists and, like Lupron, prevent premature ovulation. Lupron is a GnRH agonist and works at the hypothalamus while Ganirelix and Cetrotide are GnRH Ganirelixists block the action of GnRH on the pituitary gland. They cause a "more complete and quicker" suppression of reproductive hormones and for this reason are administered for a shorter period of time. It is sometimes necessary to use more FSH in Ganirelix/Cetrotide cycles. Ganirelix may be used with FSH to induce ovulation.

• Gonadotropin-Releasing Hormone (Gn-RH) analog: These medicines are often used for women who don't ovulate regularly each month. Women who ovulate before the egg is ready can also use these medicines. Gn-RH analogs act on the pituitary gland to change when the body ovulates. These medicines are usually injected or given with a nasal spray.

• Letrozole (Femara). This drug is in a class of medications called aromatase inhibitors, which was originally approved for treatment of advanced breast cancer. Doctors sometimes prescribe letrozole for women who don't ovulate on their own and who haven't responded to treatment with clomiphene citrate. Letrozole is not approved by the FDA for inducing ovulation. The drug's manufacturer has warned doctors not to use the drug for fertility purposes because of possible adverse health effects. These adverse effects may include birth defects and miscarriage. 

• Lupron (Leuprolide Acetate): Lupron is a GnRH agonist that works in the hypothalamus to suppress pituitary and ovarian function.  In one protocol, the drug is typically administered late in the cycle before ovarian stimulation, and continues until the eggs are mature. Lupron shuts down the patient's reproductive hormone system and eliminates a potential premature LH surge. When the LH surge occurs in a natural non-stimulated cycle, it initiates ovulation. Lupron prevents the LH surge in stimulated cycles thus preventing ovulation before the eggs are retrieved. In select cases, Lupron is administered in dilute form early in the cycle, known as the mircroflare protocol, to assist in the production of eggs. There is a characteristic "spike" in FSH levels when Lupron therapy first begins.

• Metformin (Glucophage): Doctors use this medicine for women who have insulin resistance and/or PCOS. This drug helps lower the high levels of male hormones in women with these conditions. This helps the body to ovulate. Sometimes clomiphene citrate or FSH is combined with metformin. This medicine is usually taken by mouth.

• Ovidrel: A genetically engineered pure form of hCG, which is also used to induce ovulation.

• Pregnyl, Novarel: hCG is commonly utilized to trigger ovulation after the administration of gonadotropins or in patients with severe hormone deficiencies. This medication induces ovulation 36 hours after its administration in a “properly primed” follicle. Because of this phenomenon, egg retrieval usually occurs between 34-35 hours after the administration of LH.

• Progesterone: Progesterone is administered to support the development of the endometrium, which must thicken and become more vascular to support the developing embryo and fetus.