The delivery of (or the process of delivering) a conceptus before there is a viable fetus.

Traditionally, any miscarriage revealed to be complete upon careful inspection of the expelled pregnancy tissue (the "products of conception", meaning that a uterine curettage was not necessary to avoid the risk of retained tissue causing more bleeding or infection. Nowadays we can distinguish a complete from an incomplete miscarriage (and whether or not a curettage should be done) with a transvaginal ultrasound, which can reveal significant retained tissue.

(IMC) Any miscarriage before all miscarriage tissue has been expelled. Traditionally a uterine curettage was done after a miscarriage, in the belief (often accurate) that there would still be some immature pregnancy tissue left in the uterus that could cause more bleeding and get infected. Nowadays we can distinguish an incomplete from a complete miscarriage (and whether or not a curettage should be done) with a transvaginal ultrasound, which is able to reveal significant retained tissue. Management is similar to the management of an inevitable miscarriage (and both are abbreviated IMC).

(IMC) Traditionally any bleeding from the vagina during early pregnancy with, on vaginal examination, opening of the cervix. Today, the diagnosis can be made much sooner (and distinguished from a threatened miscarriage) by not detecting a normal embryo in a gestational sac on transvaginal ultrasound. Management is similar to the management of an incomplete miscarriage, often requiring curettage (and both are abbreviated IMC).

For our purpose in the book, the loss of an early embryo at or before the expected time of a period. Not noticeable without specially measuring levels of serum human chorionic gonadotropin One form of so-called biochemical pregnancy.

The percentage chance that a pregnancy will end as a miscarriage. The normal rate of clinically apparent miscarriage for young women is about 12 percent. The rate rises independently with age, the number of previous pregnancies, and especially the number of previous miscarriages experienced. The rate is also higher with many causes of infertility when conception occurs with or without treatment.

A series of three or more consecutive miscarriages.

An early miscarriage, usually within a week or two of the period that had been expected. Traditionally, no curettage was needed; these days a subclinical miscarriage is one that has not resulted in a gestational sac visible on transvaginal ultrasound.

Traditionally, any bleeding from the uterus during pregnancy while the cervix is (still) closed. Today, as well, there would need to be a normal embryo and, a little later, normal fetal heart movement pattern on transvaginal ultrasound to separate it from an inevitable miscarriage.

Strictly, synonymous with spontaneous abortion or miscarriage. Loosely, an induced abortion for early termination of pregnancy.

When implantation occurs in one or other outer angle of the triangular cavity uterus (that is, out to one side, very close to where the fallopian tubes enter the endometrial cavity). A miscarriage is common. Rupture of the uterus has been reported.

(ACA) An antibody that acts against components in the cell membranes (membranes that holds a cell together as well as surrounding some internal cell structures). Looked for in the blood (we ask for a serum anticardiolipin as a possible immune cause of recurrent miscarriages. Intriguingly, the membrane that contains most cardiolipin is the membrane surrounding the mitochondrion (malfunction of which is implicated in causing miscarriage, although how (or if) the antibody might get to the mitochondria is not known.

Synonym: antinuclear factor. An antibody directed at phosphate-containing fatty components of cell membranes, such as cardiolipin (see anticardiolipin antibody). Low levels are probably common and harmless; in higher levels they can cause disease, particularly during pregnancy, including thrombosis and miscarriage.

Remember chromosomes occur in pairs in all cells except sperm and eggs. If part of one chromosome is found connected to a completely different chromosome it's "translocated". For that person there is no net gain or loss of genetic material, so the translocation is "balanced" and there is no problem. But when that person makes eggs or sperm, some of these will have too much or too little genetic material. The same will be true for an embryo that results. The chromosomal translocation will then be "unbalanced" and the embryo will sooner or later usually result in a miscarriage. If the two particular chromosomes have swapped parts, we call it a balanced reciprocal translocation.

A somewhat insensitive term for when conception and implantation have occurred, producing a positive pregnancy test, but without sign of a gestational sac appearing on transvaginal ultrasound; in other words, a subclinical miscarriage or a menstrual miscarriage.

Stage of development of the early embryo that has undergone blastulation, in which a fluid-filled cavity forms in the formerly solid ball of cells (the morula), about 5 days after fertilisation. For the first time, a distinction can be made between a sheet of cells to one side, which will form the embryo proper, termed the inner cell mass, and the remaining, peripheral cells that constitute the trophectoderm, which -- after the blastocyst "hatches" through the zona pellucida and undergoes implantation -- will form the trophoblast. An old-fashioned term for an inevitable miscarriage, meaning that the ovum (in its classical sense for professional embryologists) has not developed normally after fertilisation, there being present just the supporting tissues and no embryo. The term is descriptive, it has no diagnostic value as to the cause of the miscarriage.

Most commonly done before an operation that could cause significant loss of blood, especially if an ectopic pregnancy is suspected, because a blood transfusion might be needed. Also done for investigation of recurrent miscarriages, when the rare but important antibody anti-TjA needs to be excluded or detected. Rh-negative women who have a Rh-positive partner who are treated for miscarriage or for ectopic pregnancy often require an injection of Rhogam or anti-D gamma globulin to avoid being sensitised (developing antibodies to) possibly Rh Positive red blood cells from the embryo or fetus.

A defect of intestinal absorption caused by abnormal sensitivity to gluten in the diet that can first manifest with recurrent miscarriage or unexplained infertility, despite an absence of diarrhea or other disturbances of bowel function. Diagnosis is suggested by serum antigliadin antibodies and serum tissue transglutaminase (or endomysial) antibodies, but requires biopsy of the lining of the small intestine via gastroscopy for confirmation. Responds to a gluten-free diet.

Weakness of the cervix of the uterus revealed during pregnancy, usually because of previous operations on it, but sometimes without prior injury, leading to miscarriage, typically in the second three months of the pregnancy. Diagnosed by examining the cervix during the pregnancy, repeatedly if necessary. Often causes no symptoms until the waters break (the pregnancy membranes from the gestational sac bulge through the opening cervix), when it's usually too late to treat. Treated before rupture of the membranes with a cervical ligature.

When the embryo or fetus is abnormal because of a mistake in its number of chromosomes (see aneuploid and polyploid), with too much or too little genetic material. Usually causes miscarriage. Revealed by performing a karyotype on the products of conception.

A complex set of blood and tissue components capable of a cascade of events causing blood to clot. The central event is the conversion of soluble fibrinogen to insoluble, polymerised fibrin through the action of thrombin. In a more moderate way, the coagulation system (and these molecules) lay down the scaffolding for normal development of the placenta, so that abnormalities of blood coagulation may contribute to recurrent miscarriages.

The percentage of months or treatment cycles that result in conception, including biochemical pregnancies, ectopic pregnancies, miscarriages and all potentially viable pregnancies (twins are not counted twice); less important for most purposes than the implantation rate, pregnancy rate, viable pregnancy rate and the take-home-baby rate.

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).

Literally, pathology of the embryo (or fetus). Can underlie a miscarriage or, if it reflects are more or less permanent state, can cause unexplained infertility.

Elective single embryo transfer. Choosing to have just one embryo transferred after in vitro fertilisation even though there is more than one embryo that is suitable; the other suitable embryos are frozen and stored. A strategy to increase the chance of taking home a baby by minimising the risk of multiple pregnancy, which carries a higher risk of miscarriage and stillbirths.

A controversial and emotionally hazardous way of dealing with a higher-order multiple pregnancy (such as quadruplets, quintuplets, or higher) in which, all the embryos or fetuses are at risk of being lost before viability. The technique involves carrying out transvaginal ultrasound and injecting a lethal substance (such as air or a solution of potassium) into the visibly beating heart of one or more of the embryos, so reducing the number of surviving embryos to three, two or one. Generally regarded as a more stressful procedure than even an induced abortion, both for the person undergoing the operation and for the ultrasound doctor asked to do it. Few people regard the availability of fetal reduction to mean that the greatest care does not need to be taken to avoid higher-order multiple pregnancies in assisted conception programs. There's a hazard: loss of the remaining fetuses from miscarriage; but the risk of this, with an experienced ultrasound doctor or fetal medicine specialist, is low.

A polymer that is formed from the circulating protein fibrinogen when blood clots (see coagulation system). Also important in the formation of the placenta, so abnormalities of fibrinogen can cause recurrent miscarriage.

A benign "tumor" of the muscular wall of the uterus (the myometrium). More common with increasing age, but can occur in women in their twenties. Can be single or multiple, and can be located on the outside of the uterus (a subserous fibroid), within the wall of the uterus (an intramural fibroid), or protruding into the cavity of the uterus (a submucous fibroid. The closer it is (or they are) to the endometrial cavity, the more likely it is that a fibroid will disturb reproduction (either as miscarriages or sometimes as infertility) and disturb menstrual bleeding. Surgery for removal of a fibroid, or myoma, is called a myomectomy.

A rather insensitive way of referring to recurrent miscarriages.

A naturally occurring 'anticoagulant', or substance that stops blood from clotting. Used in medicine generally to prevent or to treat thrombosis, and sometimes in pregnancy to reduce the risk of miscarriage in someone who has had recurrent miscarriages by improving blood flow in the placenta. Administered by injection under the skin.

Proteins present on the surface of cells that are needed for cells stick to each other with the help of adhesion molecules. Important in implantation and in the proper construction of the placenta, so that abnormalities or mutations can result in infertility or recurrent miscarriage.

A signalling molecule that inhibits the immune system, so preventing rejection of the fetus during pregnancy. It is thought that insufficient interleukin 10 is a cause of miscarriage.

Adhesions inside the endometrial cavity caused by prior infection (endometritis), especially if there has been a curettage during the period of infection, or if curettage is performed in conditions of low estrogen. The circumstances in which this combination is most common are treatment for a missed abortion and treatment of a postpartum hemorrhage (bleeding a few weeks after the birth of a baby). A cause of absent periods amenorrhea, light periods (hypomenorrhea) or recurrent miscarriages.

An antibody first noted in the disease systemic lupus erythematosus or 'lupus', that has the ability to stop blood clotting. A cause of recurrent miscarriages. Closely related to a family of anti-phospholipid antibodies, especially anticardiolipin antibody. Also called the lupus inhibitor.

(LPD) A luteal phase that is shorter than optimal for a fertilised egg to undergo implantation. Very likely if the luteal phase is shorter than normal (11 to 16 days), but not all luteal phases within this range are innocent. Often caused by a prior defect of the follicular phase or of the development of the ovulating tertiary follicle (the preovulatory follicle) and hence there can be a defect of the egg itself (if ovulation has actually occurred) or there can be a luteinised unruptured follicle -- any of which will either increase the risk of miscarriage or will prevent pregnancy altogether for that cycle. Synonymous with luteal phase insufficiency.

A plastic operation on the uterus to change the shape of its cavity, usually for a uterine septum or for a bicornuate uterus, if there have been a number of miscarriages.

A miscarriage that should have happened but hasn't. As a result, the pregnancy tissue in the uterus gets tougher and more difficult to get out with a uterine curettage -- which is the only treatment for it, but risks producing intrauterine adhesions. The pregnancy test can stay positive for many weeks or even months.

Repeated loss of pregnancies at different stages of development of the embryo or fetus, i.e. at different stages of pregnancy. Related to recurrent miscarriages.

Mitochondrial DNA. The small amount of DNA found in the mitochondria. mtDNA is the genetic code for 13 proteins involved in metabolism. Because mtDNA is much less stable than the DNA in the chromosomes (where the huge bulk of genetic code is stored), mutations accumulate with time at a greater rate than that for chromosomal DNA -- and eventually limit how well a particular cell or tissue can function with increasing age. Because all of the mtDNA you have you inherited from your mother (you derive your mitochondria from the egg you came from), we could have an explanation: (1) why all eggs are formed before birth (so the mitochondria don't have to keep on dividing too often and risking genetic errors); and (2) why miscarriages and infertility get commoner with age (as the egg's several thousand mitochondria begin to succumb to genetic errors).

A polymorphism affecting the metabolism of folic acid with a number of possible consequences avoidable by increasing dietary supplements to mega-doses (5 mg to 10 mg per day), including promotion of blood coagulation, or thrombophilia, abnormalities of the fetus (birth defects, especially neural tube defects such as spina bifida and anencephaly), recurrent miscarriage, an increased chance of heart disease and coronary thrombosis, and in men, possibly contributes to oligospermia and infertility.

The muscular wall of the uterus, surrounding the endometrium. The myometrium contracts (1) during menstruation perhaps causing dysmenorrhea, and (2) during miscarriage or labor to deliver the conceptus.

A new term for the normal cessation of female fertility up to 10 years before the menopause, being apparent in some women after the age of 33 and most women by 45. Different from the perimenopause, which occurs as egg numbers fall far enough to cause shortening of the menstrual cycle, particularly the follicular phase, and accompanied by elevation of serum FSH when measured during menstruation. If pregnancies are attempted through the oopausal transition, a woman who has had no prior reproductive disturbance will typically experience recurrent miscarriages before developing otherwise unexplained infertility, manifesting in the IVF lab sequentially with unexplained implantation failure of apparently satisfactory embryos, then, in turn, a decreased rate of forming blastocysts, defective cleavage, and then failure of fertilisation. There is no known method of overcoming its effects short of egg donation, except for some hope that the procedure of cytoplasmic transfer might be helpful.

A measurement of sugar (glucose) in the blood plasma to detect diabetes, an occasional cause of recurrent miscarriages. Usually checked a few hours after a meal or, more formally, with a glucose tolerance test that involves a standard drink of glucose (after prior fasting) followed by serial measurements of plasma glucose over 3 hours.

An abnormality of the embryo (or fetus) that arises after implantation of the embryo in the endometrium (the lining of the uterus). Might, sooner or later, cause a miscarriage or birth abnormality.

The percentage of months or treatment cycles that result in clinical pregnancy, excluding biochemical pregnancy, but including ectopic pregnancy, miscarriage and all potentially viable pregnancies (twins are not counted twice; stillbirths and all live births are included). Less important for most patients' purposes than the take-home-baby rate. Less useful for embryologists intent on quality control in the laboratory than the implantation rate.

Nowadays a measurement of human chorionic gonadotropin in serum or urine, usually as a simple 'yes' or 'no' test. In principle a single test cannot distinguish a normal pregnancy from an ectopic pregnancy or one destined to miscarry (a miscarriage).

An abnormality of the embryo (or fetus) that arises before the embryo undergoes implantation in the endometrium (the lining of the uterus). Usually causes miscarriage.

Trouble getting pregnant (infertility) in someone who has never had a successful pregnancy. Although the exact definition can vary among gynecologists, the differentiation between primary infertility and secondary infertility is most useful if a prior ectopic pregnancy or a prior miscarriage is consistent with the state of primary infertility, whereas a prior induced abortion (which, the odds are, would otherwise have developed normally) means the state is secondary infertility.

(RTF) A protein produced by the trophoblast that reduces the tendency of the mother's immune system to reject the pregnancy, apparently by increasing levels of interleukin 10, and thus reducing the tendency for miscarriage.

Trouble getting pregnant (infertility) in someone who has previously had a successful or potentially successful pregnancy. Although the exact definition of secondary infertility can vary among gynecologists, for me the distinction between secondary infertility and primary infertility is most useful if the term secondary infertility is restricted to when there has been a prior induced abortion (which, the odds are, would otherwise have developed normally) or a successful pregnancy; a prior ectopic pregnancy or a prior miscarriage is, in my view, still the state of primary infertility.

One of a number of tests to detect previous or untreated syphilis, an important (though nowadays rare) cause of birth defects and recurrent miscarriages. The chance of detecting unsuspected syphilis might be very low, but the penalty for missing it is very high, so it's still a routine test in early pregnancy. Tests are done on serum and include the Venereal Disease Research Laboratory (VDRL) test and the Wasserman reaction (WR) test. Often tested as part of a screen for infectious disease before assisted conception, although there is no evidence that syphilis is transmitted through eggs or sperm (it is caught from contact between the lining of the vagina and the surface of the penis).

A test done to investigate recurrent miscarriages.

Done to screen for Wilson's disease, in which there is abnormal retention of copper in the body -- a rare cause of recurrent miscarriages.

Measurement of human chorionic gonadotropin in serum: essentially a pregnancy test, but carried out more precisely (quantitatively) than is the case with a yes or no test (which is qualitative). Often carried out serially, to determine if a pregnancy is: thriving (hCG levels double every two or three days in normal early pregnancy; languishing (levels rise more slowly, seen with an ectopic pregnancy and with an inevitable miscarriage); or resolving naturally (levels that are falling). Very high levels are seen with hydatidiform mole. Part of the triple screen used to screen for Down syndrome in early pregnancy.

A test of kidney function. Sometimes measured when screening for a kidney (renal) cause of recurrent miscarriages.

(SCSA) A measurement of the proportion of sperm cells that have damaged DNA. Fewer than 15% is consistent with normal fertility; 15%-30% can result in subfertility; and more than 30% may cause sterility or recurrent miscarriage.

A fibroid (or myoma) that grows from the wall of the uterus inwards to distort the endometrial cavity. Can be a cause of menorrhagia (heavy periods), intermenstrual bleeding, premenstrual spotting, infertility and miscarriage.

A computer enhanced transvaginal ultrasound or a multi-probe abdominal ultrasound that produces a composite, constructed three-dimensional image of the uterus, which can then be viewed from any perspective. Excellent for displaying the form of the uterus in the investigation of uterine anomalies and recurrent miscarriages.

An increase in the tendency of the blood to clot, as in 'thrombosis'. In primitive, evolutionary times, a survival advantage for women giving birth, when loss of blood would on average be less, but exacting a price in terms of increased risk of stroke or venous thrombosis. The thrombophilias are implicated in disturbances of pregnancy, including recurrent miscarriage and stillbirth.

Abbreviation for threatened miscarriage.

Literally, a three-month period of time; so the nine months of pregnancy are divided into the first, second and third trimesters. Most miscarriages take place in the first trimester (up to 12 or 13 weeks). Pregnancies that reach the third trimester (beyond 27 weeks) have an increasingly good chance of being viable (though nowadays, with intensive care, survival has occurred from about 24 weeks).

A uterine anomaly that comes about when the uterus forms (in the embryo) from just one Mullerian duct; the uterus will be a little smaller than normal (making a miscarriage or premature labor more likely), and will be connected by a fallopian tube to just one ovary, contributing slightly to infertility (since, on average, only half of ovulations have a chance of resulting in pregnancy). Reproduction, however, can be normal, and a woman might go through life with a unicornuate uterus and not know it. Diagnosed by hysteroscopy and laparoscopy, by hysterosalpingogram or -- particularly effectively -- by three-dimensional ultrasound. Often there is a simultaneous abnormality of the kidneys, such as one kidney instead of two, diagnosable by abdominal ultrasound or, more specifically, by a special kidney x-ray study called an intravenous pyelogram.

Abnormality of the shape of the uterus a woman is born with (it is congenital); some uterine anomalies tend to cause recurrent miscarriages, premature labor or breech births.

A septum or wall separating the cavity of the uterus into two halves; a cause of recurrent miscarriages.

The womb, in which pregnancy is gestated from the time of implantation of the embryo until delivery or miscarriage; formed from the joining of the two Mullerian ducts (in the absence of anti-Mullerian hormone); composed of the main, upper part (the uterine fundus) and a lower neck, or cervix, which connects it to the upper part of the vagina; most of its wall is made of muscle tissue (the myometrium), but with an inner lining of glands (the endometrium) and, on the outer surface, a thin covering of uterine serosa. Best seen on transvaginal ultrasound, especially a three-dimensional ultrasound; its cavity is best displayed with a hysterosalpingogram (or, strictly, a hysterogram).

Curettage in which the contents of the early pregnant uterus are sucked out using a soft plastic catheter. Used in the treatment of miscarriage, in the treatment of hydatidiform mole, and to induce abortion.

(VEGF) A growth factor (or local hormone) needed for new blood vessels to form in, for example, the corpus luteum, as it turns into an efficient hormone-producing gland making and releasing progesterone about a week after ovulation. Because such new blood vessels are rather leaky, excess VEGF from multiple corpora lutea during ovulation induction or superovulation using gonadotropins can be associated with new blood vessels trying to form in the general peritoneal cavity, leakage of fluid from which causes fluid to build up in the abdomen, a potentially dangerous condition known as the ovarian hyperstimulation syndrome. VEGF is also important in the formation of the placenta, so mutations of VEGF or its target proteins can cause recurrent miscarriage.

A sac-like structure attached to the under-surface of the developing embryo. The first part of the embryo to become visible on transvaginal ultrasound after the gestational sac, but not by itself as reassuring as seeing a beating fetal heart that the pregnancy will most likely avoid miscarriage. Not as important for a human embryo's nutrition as it is for a fertilised egg incubated by a hen, and in mammals contains no yolk, but the yolk sac's lumen is continuous with the lumen of the embryo's developing gut, or intestine, and shares an absorptive function. Cells from the yolk sac become incorporated into the fetus in many ways, including forming the primitive germ cells.