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Radiation --- a general term for any form of radiant (emitting beams of light) energy emission. Ionizing radiation has the ability to penetrate cells and deposit energy and can cause radiation injury to the cells.

RE -- See Reproductive Endocrinologist.

Reactive Oxygen Species (ROS) -- Oxygen free radicals. High levels of ROS generation are linked a reduced ability of sperm to bind to the zona pellucida. Vitamin E may significantly improve this aspect of sperm function.

Recombinant (Human) Follicle Stimulating Hormone (R-FSH, R-hFSH) -- Genetically engineered follicle stimulating hormone as opposed to FSH extracted from the urine of post menopausal women. It is synthesized in vitro by cells into which genes encoding for FSH subunits have been inserted. Brand names are Gonal-F and Follistim.

Recurrent Pregnancy Loss (RPL), Recurrent Miscarriage, Recurrent Spontaneous Abortion (RSA) -- Repeated miscarriages. Testing can be done to try to determine the cause of such losses. If an underlying condition is found, the woman may need to be treated for the problem before a pregnancy can be carried to term.

Reproductive Endocrinologist (RE) -- A medical specialty combining obstetrics and gynecology with endocrinology to treat reproductive disorders. RE's as they are referred to usually have a 2-3 year fellowship in the specialty of reproductive endocrinology and infertility.

Reproductive Immunologist (RI) -- A medical specialty combining obstetrics and gynecology with immunology to treat reproductive disorders that are related to immune problems.

Reproductive Immunophynotype (RIP) -- A test which looks for cells that have the CD56+ marker in order to determine the portion of natural killer cells. An NK (CD56+) cell range above 12 percent is abnormal.

Reproductive Surgeon -- An ob-gyn or urologist who specializes in the surgical correction of anatomical disorders that affect reproductive function.

Repronex (hMG) -- A medication used to replace the pituitary hormones LH and FSH. Similar to Humegon and Pergonal. May be used to induce ovulation in women who do not respond to clomiphene citrate. Most frequently used with women who do not normally produce estrogen because of a pituitary gland or hypothalamic malfunction. May also be used with men to stimulate sperm production.

R-FSH, R-hFSH -- See Recombinant (Human) Follicle Stimulating Hormone.

Resistant Ovary -- An ovary that cannot respond to the follicle-stimulating message sent by FSH. Primitive germ cells will be present in the ovary; however, they will not respond to FSH stimulation.

Retrograde Ejaculation -- A male fertility problem that allows the sperm to travel into the bladder instead of out the opening of the penis due to a failure in the sphincter muscle at the base of the bladder.

Retroverted Uterus -- Uterus that is tilted back toward the rectum.

Reversal -- Term used in infertility for undoing a sterilization procedure such as a tubal ligation or vasectomy.

Rh Factor -- Any of one or more genetically determined antigens present in the red blood cells of most persons and capable of inducing intense immunologic reactions. Some women develop a sensitization to Rh during pregnancy. If a woman is Rh negative and her husband is Rh positive, she is a candidate for Rh incompatibility problems. After the first pregnancy, the Rh factor enters the Rh-negative mother's circulatory system during the delivery (or miscarriage) of a child who has inherited the Rh factor from his father. The mother's body then produces antibodies against it. If she becomes pregnant with another Rh-positive baby, the antibodies cross the placenta and attack the baby's red blood cells, causing mild to serious anemia in the baby. The medication Rhogam (called "Anti-D" in Britain and New Zealand) is given to prevent these problems.

Rhogam (Anti-D) -- an immunization given to Rh-negative women after a miscarriage, stillbirth, or live birth to prevent production of antibodies in any Rh-positive babies they may have in future pregnancies.

RIP -- See Reproductive Immunophynotype.

ROS -- See Reactive Oxygen Species.

RPL -- See Recurrent Pregnancy Loss.

RSA -- See Recurrent Spontaneous Abortion.