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Habitual Abortion -- Repeat miscarriages. See article

Hamster Test -- A test of the ability of sperm to penetrate a hamster egg that has been stripped of the Zona Pellucida (outer membrane). Also called Sperm Penetration Assay (SPA).

Haploid --- A single set of chromosomes (half the full set of genetic material), present in the egg and sperm cells of animals and in the egg and pollen cells of plants. Human beings have 23 chromosomes in their reproductive cells.

hCG/HCG -- See Human Chorionic Gonadotropin.

Hemorrhage -- Profuse, life-threatening bleeding.

Heparin -- A blood thinner given as an injection to prevent blood clots from forming.

Heparin Therapy -- The use of Heparin to thin blood in women with recurrent pregnancy loss or presence of an autoimmune problem, such as antiphospholipid antibodies.

Hermatospermia -- Condition in which blood appears in the semen and may usually be seen by the naked eye.

Hirsutism -- The overabundance of body hair, such as a mustache or pubic hair growing upward toward the navel, found in women with excess androgens. See PCOS FAQ

hMG, HMG -- See Human Menopausal Gonadotropin.

Home Pregnancy Test (HPT) -- A test a woman can use at home to test urine for the presence of hCG.

Hormone -- A substance produced by an endocrine gland that trabelss through the bloodstream to a specific organ.

Hormone Replacement Therapy (HRT) -- Refers to estrogen and progesterone replacement in menopausal women.

Host Uterus -- Also called a "surrogate gestational mother." A couple's embryo is transferred to another woman who carries the pregnancy to term and returns the baby to the genetic parents immediately after birth.

Hostile Mucus -- Cervical mucus that impedes the natural progress of sperm through the cervical canal.

HPT -- See Home Pregnancy Test.

HRT -- See Hormone Replacement Therapy.

HSC -- See Hysteroscopy.

HSG -- See Hysterosalpingogram.

Human Chorionic Gonadotropin (hCG) -- The hormone produced in early pregnancy which keeps the corpus luteum producing progesterone. Also used via injection (Profasi) to trigger ovulation after some fertility treatments, and used in men to stimulate testosterone production. See beta chart

Human Menopausal Gonadotropins (hMG = Pergonal, Humegon, Repronex) -- A combination of hormones FSH and LH, which is extracted from the urine of post-menopausal women. Used to induce ovulation in several fertility treatments.

Humegon (hMG) -- Similar to Pergonal and Repronex: the luteinizing and follicle-stimulating hormones recovered from the urine of post-menopausal women. Used to stimulate multiple ovulation in some fertility treatments.

Hydatidiform Mole -- See Molar Pregnancy.

Hyperandrogenism -- The excessive production of androgens in women. Often associated with PCOS.

Hyperglycemia -- High blood sugar.

Hyperinsulinemia -- The overproduction of insulin such as that found in insulin resistance.

Hyperplasia -- A thickening of the endometrium. It can lead to abnormal, pre-cancerous cells.

Hyperprolactinemia -- A condition in which the pituitary gland secretes too much prolactin. Prolactin can suppress LH and FSH production, reduce male sex drive, and directly suppress ovarian function.

Hyperstimulation (Ovarian Hyperstimulation Syndrome, OHSS) -- A potentially life-threatening side effect of ovulation induction with injectable fertility medications such as hMG and urofollitropins. A woman's ovaries become enlarged and produce an overabundance of eggs. Blood hormone levels rise, fluid may collect in the lungs or abdominal cavity, and ovarian cyst may rupture, causing internal bleeding. Bloodclots sometimes develop. Symptoms include sudden weight gain and abdominal pain. Cycles stimulated with these drugs must be carefully monitored with ultrasound scans. OHSS may be prevented by withholding the hCG injection when ultrasound monitoring indicates that too many follicles have matured.

Hyperthyroidism -- Overproduction of thyroid hormone by the thyroid gland. The resulting increased metabolism "burns up" estrogen too rapidly and interferes with ovulation.

Hypoestrogenic -- Having lower than normal levels of estrogen.

Hypoglycemia -- Low blood sugar.

Hypogonadotropic Hypopituitarism --- A spectrum of diseases resulting in low pituitary gland output of LH and FSH. Men with this disorder have low sperm counts and may lose their virility; women do not ovulate and may lose their secondary sex characteristics.

Hyponatremia - A condition that occurs when the level of sodium in your blood is abnormally low. Sodium is an electrolyte, and it helps regulate the amount of water that's in and around your cells. In hyponatremia, one or more factors — ranging from an underlying medical condition to drinking too much water during endurance sports — causes the sodium in your body to become diluted. When this happens, your body's water levels rise, and your cells begin to swell. This swelling can cause many health problems, from mild to life-threatening.Hyponatremia treatment is aimed at resolving the underlying condition. Depending on the cause of hyponatremia, you may simply need to cut back on how much you drink. In other cases of hyponatremia, you may need intravenous fluids and medications.

Hypoplastic Uterus -- An underdeveloped uterus.

Hypospermatogenesis -- Low sperm production.

Hypothalamus -- A part of the brain, the hormonal regulation center, located adjacent to and above the pituitary gland. In both the man and the woman this tissue secretes GnRH every ninety minutes or so. The pulsatile GnRH enables the pituitary gland to secrete LH and FSH, which stimulate the gonads. See also FSH; LH; Ovary; Pituitary Gland; Testicle.

Hypothyroidism -- A condition in which the thyroid gland produces an insufficient amount of thyroid hormone. The resulting lowered metabolism interferes with the normal breakdown of "old" hormones and causes lethargy. Men will suffer from a lower sex drive and elevated prolactin (see Hyperprolactinemia), and women will suffer from elevated prolactin and estrogen, both of which will interfere with fertility.

Hysterosalpinogram (HSG) -- An x-ray of the pelvic organs in which a radio-opaque dye is injected through the cervix into the uterus and fallopian tubes. This test checks for malformations of the uterus and blockage of the faloipian tubes.

Hysterectomy -- Surgical removal of the uterus and sometimes also the cervix.

Hysteroscopy (HSC) -- A procedure in which the doctor checks for uterine abnormalities by inserting a fiber-optic device. Minor surgical repairs can be executed during the procedure.