Glossary for the Public

AMNION: The tissue membrane that expands to enclose the fetus and form the AMNIOTIC SAC, protecting and cushioning the fetus during pregnancy, within which is the AMNIOTIC FLUID (bag of water).

ANENCEPHALY: Absence of development of the brain and related structures which leads to stillbirth or death soon after birth.

AUTOPSY (Postmortem): Examination of the internal organs after death.

CHORIOAMNIONITIS: Inflammation of the membranes that surround the fetus.

CHORION: Outer membrane surrounding the fetus inside of which is the amnion, amniotic fluid and developing fetus.

CHROMOSOMES: Thread-like structures found in the body's cells that carry the genetic material. The normal human chromosome number is 46, made up of 23 pairs.

CHROMOSOME ANALYSIS (KARYOTYPE): A picture of the chromosomes of an individual arranged in a standard manner so that abnormalities of chromosome number or form can be identified.

CYTOGENETICS: The branch of genetics concerned mainly with the study of chromosomes and their relationship to physical features.

DOMINANT INHERITANCE: The situation in which the inheritance of one copy of a poorly functional or abnormal gene from one parent results in the expression of a syndrome or disease in the offspring. (That is, the one poorly functional or abnormal gene dominates over the normal copy of the gene in the pair, and the syndrome or disease is expressed.)

DOWN SYNDROME: See Trisomy 21.

DYSMORPHOLOGY: The medical specialty concerned with the identification of and delineation of syndromes or congenital abnormalities based on understanding their physical features.

ECTOPIC PREGNANCY: (EXTRA-UTERINE PREGNANCY) Development of a fetus at a site other than the uterus. The most common type of ectopic pregnancy is a TUBAL PREGNANCY, in which the fertilized egg remains in the fallopian tube which leads from the ovary to the uterus.

FETOMATERNAL HEMORRHAGE: Loss of fetal blood through leakage into the mother's circulation. Large volumes of fetal blood loss can cause stillbirth.

GENETICS COUNSELING: Genetics counseling is a communication process which deals with the human problems associated with the occurrence, or the risk of an occurrence, of a genetic disorder in a family. This process involves an attempt by appropriately trained persons to help the individual or family to (1) comprehend the medical facts, including the diagnosis, probable course of the disorder, and the available management; (2) appreciate the way heredity contributes to the disorder, and the risk of recurrence in specified relatives; (3) understand the alternatives for dealing with the risk of occurrence; (4) choose the course of action which seems to them appropriate in view of their risk, their family goals, and their ethical and religious standards, to act in accordance with that decision; and (5) to make the best possible adjustment to the disorder in an affected family member and/or to the risk of recurrence of that disorder.

GENOTYPE: The overall genetic makeup of an individual.

INTRAUTERINE DEATH: Death of an embryo or fetus within the uterus; can refer to a miscarriage or a stillbirth, depending on number of weeks gestation at time of death.

KARYOTYPE: See chromosome analysis.

KLEIHAUER-BETKE: A blood test performed on the mother's blood to identify whether substantial bleeding has occurred from the fetus into the mother's circulation.

MISCARRIAGE: (SPONTANEOUS ABORTION) Death of an embryo or fetus prior to 20 weeks gestation.

MONOSOMY X: See Turner Syndrome.

MULTIFACTORIAL INHERITANCE: Inheritance of traits that are determined by a combination of the effects of many genes and environmental factors.

NEONATAL DEATH: Death of a liveborn infant between birth and 4 weeks of age.

NEURAL TUBE: Embryological structure which gives rise to the brain and spinal cord.

NEURAL TUBE DEFECT: Failure of part of the neural tube to close, which can result in a number of birth defects, such as spina bifida (opening in the spine) or anencephaly (failure of brain development)

NUCHAL CORD: A common condition in which the umbilical cord is wrapped around the neck of the fetus in utero or of the baby as it is being born.

PATHOGENETIC: Causing disease.

PERINATAL DEATH: All stillbirths plus all neonatal deaths.

PHENOTYPE: The observed biochemical, physiological, and physical characteristics of an individual, as determined by his or her genotype and the environment in which it is expressed.

PLACENTA: Organ within the uterus that allows passage of substances between mother and fetus, such as food and oxygen.

PLACENTAL ABRUPTION: Premature separation of the placenta from its attachment to the uterine wall that may cause stillbirth.

PLACENTAL INFARCTION: Death of part of the placenta which, if extensive enough, can cause stillbirth.

RECESSIVE INHERITANCE: The situation in which inheritance of the same poorly functional or abnormal gene from both parents results in the expression of a syndrome or disease in the offspring. (That is, two copies of the poorly functional or abnormal recessive gene are required for the syndrome or disease to be expressed.)

SPINA BIFIDA: A birth defect of variable severity and prognosis that may allow outpouching of the meninges, spinal cord, spinal muscles and associated nerves resulting from the failure of the neural tube to close properly during very early embryonic development (by 28 days gestation) resulting in abnormalities of the spinal cord.

STILLBIRTH (INTRAUTERINE DEATH, FETAL DEMISE, FETAL DEATH): The death prior to delivery of a baby with a gestation of at least 20 weeks or a birth weight of greater than 350 grams.

SYNDROME: A characteristic pattern of anomalies resulting from one underlying cause.

TRIPLOIDY: Having three copies of each chromosome, for a total of 69 chromosomes, rather than the normal two copies of each.

TRISOMY 18: A severe chromosomal disorder caused by the presence of an extra #18 chromosome. If liveborn, death usually occurs by 6 months, although some children may survive for years.

TRISOMY 13: A severe chromosomal disorder caused by the presence of an extra #13 chromosome. If liveborn, death usually occurs by 6 months, although a rare child may survive for years.

TRISOMY 21: Also known as Down syndrome, trisomy 21 is the most common chromosomal disorder. This syndrome is caused by the presence of an extra #21 chromosome and is highly variable clinically. Some infants with trisomy 21 are stillborn. In liveborn children mental retardation may range from mild to severe/profound.

TURNER SYNDROME: Also known as Monosomy X, Turner syndrome is the result of a missing X chromosome in a female. Although the rate of miscarriage and stillbirth is very high, those who are liveborn generally good health, a normal life span and normal intelligence.

TWIN-TWIN TRANSFUSION: A transfer of blood through an accidental communication between blood vessels of identical twins.

UMBILICAL CORD: The connection between the fetus at its abdomen and the placenta, giving passage to the umbilical blood vessels.