A hormonal drug used for treating endometriosis. Related to male sex hormones (it's a weak androgen), it has occasional androgenic side effects, including weight gain and increased muscle bulk (it's also an anabolic steroid), and increased facial hair (hirsutism); less commonly their can be deepening of the voice or enlargement of the clitoris. Made by Sanofi Winthrop as Danocrine.

A GnRH-agonist, made by Ipsen Biotech as Triptorelin. Administered by a monthly injection.

Differentiated endometrium of pregnancy which is shed (like a deciduous tree sheds its leaves) at childbirth or miscarriage, as part of the afterbirth. During pregnancy it has important hormonal functions (see decidual cells).

Plump endometrial stromal cells, lying between the glands of the endometrium, formed under the prolonged influence of progesterone, especially with establishment of pregnancy. Constitutes the decidual reaction to form the decidua of pregnancy, and produce prolactin (important for regulating water entering the gestational sac) and relaxin, which keeps the myometrium quiet.

A transformation of the lining of the uterus (the endometrium) in pregnancy. Complete confluence of endometrial stromal cells (lying between the endometrial glands) occurs, caused by prolonged (14 days or more) exposure to progesterone or a progestogen; normally happens only with pregnancy.

The commonest of the alleles to result in cystic fibrosis (when two delta F508 alleles are present) or (can occur when one F508 allele is present in a man). A woman heterozygous for this gene (with one F508 allele) will be a carrier for cystic fibrosis (and for CBAVD) but will herself be otherwise normal. There are however many other faulty alleles that can also contribute to these clinical conditions. The most common alleles can be looked for at preimplantation genetic diagnosis (PGD).

A set of ethical beliefs, in which principles and values are seen by adherents to be self-evident and not in need of more basic proof. The ethical principles are duty-binding, innately known, and by nature resistant to change.

The natural process in which the older the female fetus, girl or woman gets the fewer are the eggs (as primordial follicles) left in the ovaries; the huge majority of eggs are lost because of atresia, only a tiny fraction by ovulation. Before the eggs are depleted there is a mild or moderate elevation in serum FSH when measured during the menstrual phase (often called a day 3 FSH. When the eggs are more or less depleted there will be primary ovarian failure and, in women who have had periods, the menopause will take place, perhaps prematurely (premature menopause). Infertility, however, usually precedes total egg depletion by up to 10 years. See also mitochondrion and oopause.

A formulation of the oral contraceptive pill that contains, as well as an estrogen, the progestogen known as cyproterone acetate, which is particularly effective at blocking the effects of male hormones on the skin. Made by Schering.

Use of a high voltage, high frequency electric current to coagulate or evaporate tissue during surgery. Useful because it can be used during laparoscopy, particularly for stopping bleeding (by coagulation) and for treating endometriosis (by evaporation).

(DHT) The most active male sex hormone or androgen; formed in target tissues from testosterone (which is the main form of androgen circulating in the blood). Testosterone must be converted to DHT before it can do its job (the enzyme for which is 5-alpha reductase, and a deficiency of which is a cause of intersex.

Before curettage (of the uterus), the cervix is dilated to admit the curette. Sometimes abbreviated, D & C.

The full, normal complement of chromosomes, numbering 46 (as 23 pairs).

Justice dispensed in the community to confer maximum value to those in need through the notions of fairness and consistency.

Twins formed from two fertilised eggs, or zygotes; non-identical twins.

The stuff of which genes are made. DNA is an abbreviation of deoxyribonucleic acid, a molecule made of a variable sequence of units, the nature and order of which forms the genetic code. DNA is located chiefly in the chromosomes, which form a cell's nucleus. A small amount of DNA (coding for about 13 genes) is found in the mitochondria (for which see also mtDNA).

Testing for the presence or absence of a particular sequence of DNA using molecular methods such as the polymerase chain reaction or, increasingly, with DNA arrays, or DNA chips.

The preovulatory follicle, or Graafian follicle, that has won the responsibility for producing estradiol for the rest of that particular ovarian cycle. Chosen by the end of the first week of the follicular phase. Its destruction (whether accidental or intentional) means that a new follicular phase must start, with ovulation two weeks later, whereas destruction of one of the tertiary follicles before one has become dominant causes no interference with the timing of ovulation for that cycle.

A pattern of inheritance of a characteristic (such as brown eye color) or abnormality in which just one gene or allele is needed to confer the characteristic or abnormality, in contrast to recessive inheritance, which requires two abnormal genes.

(DI) Assisted insemination in which semen from a sperm donor (who is not the husband) is used.

Due to trisomy 21. Chromosome 21 is the smallest of the "autosomes" (the non-sex chromosomes): trisomies of the other autosomes tend to be lethal at an earlier stage of embryonic or fetal development, and so are seen much more rarely. Diagnosis of Down's syndrome requires a karyotype, obtainable from pregnancy tissue by chorionic villus sampling (CVS) or amniocentesis. Screening for increased risk in pregnancy can be performed by triple screen or by looking for nuchal translucency at transvaginal ultrasound.

One of the two most important variables (the other is time left for conception) that determines the chance of still getting pregnant naturally in subfertility, including unexplained infertility. The longer the duration of infertility, the smaller the chance each month as time goes on. See also fecundability and time to pregnancy.

A moral compulsion for ethical action that is innate. The basis for deontological ethics.

(DUB) Heavy bleeding from the uterus. See anovulatory dysfunctional bleeding (often painless and irregular) and ovulatory dysfunctional bleeding (usually regular and can be associated with dysmenorrhea).

Painful menstruation. Can be primary, present in teenagers, generally in spasms around the start of the period; or it can be secondary, developing as a woman gets older, and then typically lasting more than a day or so into the period, with prolonged aching as well as spasms. Primary dysmenorrhea might have no medical importance beyond the suffering the pain causes, and typically gets better as a woman reaches her 20s; severe or persistent cases, however, warrant investigation. Secondary dysmenorrhea can signify, for example, endometriosis, fibroids, adenomyosis or peritubal adhesions.

Painful sexual intercourse that persists after the first few times or which develops after months or years of painless sex.