Biological and Environmental Foundations and Prenatal Development

amniocentesis.

A prenatal diagnostic procedure in which a small sample of the amniotic fluid is extracted from the mother’s uterus and subject to genetic analysis.

amnion.

A membrane that holds amniotic fluid.

anencephaly.

A neural tube defect that results in the failure of all or part of the brain to develop, resulting in death prior to or shortly after birth.

Apgar scale.

A quick overall assessment of a baby’s immediate health at birth, including appearance, pulse, grimace, activity, and respiration.c

behavioral genetics.

The field of study that examines how genes and environment combine to influence the diversity of human traits, abilities, and behaviors.

blastocyst.

A thin-walled, fluid-filled sphere containing an inner mass of cells from which the embryo will develop; it is implanted into the uterine wall during the germinal period.

Cesarean section.

Also known as a C-section; a surgical procedure that removes the fetus from the uterus through the abdomen.

chorionic villus sampling (CVS).

Prenatal diagnostic test that is conducted on cells sampled from the chorion to detect chromosomal abnormalities.

chromosome.

One of 46 rod-like molecules that contain 23 pairs of DNA found in every body cell; they collectively contain all of the genes.

deoxyribonucleic acid (DNA).

The chemical structure, shaped like a twisted ladder, that contains all of the genes.

dominant-recessive inheritance.

A form of genetic inheritance in which the phenotype reflects only the dominant allele of a heterozygous pair.

doula.

A caregiver who provides support to an expectant mother and her partner throughout the birth process.

Down syndrome.

A condition in which a third, extra chromosome appears at the 21st site; also known as trisomy 21. This condition is associated with distinctive physical characteristics accompanied by developmental disability.

embryo.

Prenatal organism between about 2 and 8 weeks after conception; a period of major structural development.

embryonic period.

Occurs from about 2 to 8 weeks after pregnancy, in which rapid structural development takes place.

epidural.

A method of pain management often used during labor in which a regional anesthetic drug is administered to a small space between the vertebrae of the lower spine to numb the woman’s lower body.

epigenetics.

A perspective that development results from dynamic interactions between genetics and the environment such that the expression of genetic inheritance is influenced by environmental forces.

extremely low birthweight.

Refers to a birthweight of less than 750 grams (1 lb., 10 oz.); poses serious risks for survival, developmental challenges, and handicaps.

fetal alcohol spectrum disorders.

The continuum of physical, mental, and behavioral outcomes caused by prenatal exposure to alcohol.

fetal alcohol syndrome (FAS).

The most severe form of fetal alcohol spectrum disorder accompanying heavy prenatal exposure to alcohol, including a distinct pattern of facial characteristics, growth deficiencies, and deficits in intellectual development.

fetal MRI.

Applies MRI technology to image the fetus’s body and diagnose malformations.

fetal period.

Occurs during the ninth week of prenatal development to birth, in which the fetus grows rapidly, and its organs become more complex and begin to function.

fetus.

The prenatal organism from about the ninth week of pregnancy to delivery; a period of rapid growth and maturation of body structures.

fragile X syndrome.

An example of a dominant–recessive disorder carried on the X chromosome characterized by intellectual disability, cardiac defects, and behavioral mannerisms common in individuals with autistic spectrum disorders; occurs in both males and females but is more severe in males.

gamete.

A reproductive cell; sperm in males and ovum in females.

gene.

The basic unit of heredity; a small section of a chromosome that contains the string of chemicals (DNA) that provide instructions for the cell to manufacture proteins.

gene-environment correlation.

The idea that many of an individual’s traits are supported by his or her genes and environment; there are three types of correlations: passive, reactive, and active

gene-environment interactions.

Refer to the dynamic interplay between genes and our environment in determining characteristics, behavior, physical, cognitive, and social development as well as health.

genotype.

An individual’s collection of genes that contain instructions for all physical and psychological characteristics, including hair, eye color, personality, health, and behavior.

germinal period.

Also referred to as the period of the zygote; refers to the first 2 weeks after conception.

hemophilia.

An X-linked chromosomal disorder involving abnormal blood clotting.

implantation.

The process by which the blastocyst becomes attached to the uterine wall, completed by about 10 days after fertilization.

incomplete dominance.

A genetic inheritance pattern in which both genes are expressed in the phenotype.

indifferent gonad.

A gonad in an embryo that has not yet differentiated into testes or ovaries.

Jacob’s syndrome.

A sex chromosome abnormality experienced by men in which they produce high levels of testosterone; also known as XYY syndrome.

kangaroo care.

An intervention for low-birthweight babies in which the infant is placed vertically against the parent’s chest, under the shirt, providing skin-to-skin contact.

Klinefelter syndrome.

Sex chromosome abnormality in which a male has an extra X chromosome (XXY).

labor.

Occurs at about 40 weeks of pregnancy, or 38 weeks after conception; also known as childbirth.

low birthweight.

Classifies infants who weigh less than 2,500 grams (5.5 pounds) at birth.

meiosis.

The process by which a gamete is formed, containing one half of the cell’s chromosomes, producing ova and sperm with 23 single, unpaired chromosomes.

midwife.

A health care professional, usually a nurse, who specializes in childbirth;midwives provide health care throughout pregnancy and supervise home births.

mitosis.

The process of cell duplication in which DNA is replicated and the resulting cell is genetically identical to the original.

mutation.

A sudden permanent change in the structure of genes.

natural childbirth.

An approach to birth that reduces pain through the use of breathing and relaxation exercises.

neonate.

A newborn human.

neural tube.

Forms during the third week after conception and will develop into the central nervous system (brain and spinal cord).

niche picking.

An active gene-environment correlation in which individuals seek out experiences and environments that complement their genetic tendencies.

noninvasive prenatal testing (NIPT).

A prenatal diagnostic that samples cell- free fetal DNA from the mother’s blood for chromosomal abnormalities.

phenotype.

A person's observable physical traits, such as eye color, hair color, or height.

phenylketonuria (PKU).

A recessive disorder that prevents the body from producing an enzyme that breaks down phenylalanine (an amino acid) from proteins that, without treatment, leads to buildup that damages the central nervous system.

placenta.

The principal organ of exchange between the mother and the developing organism, enabling the exchange of nutrients, oxygen, and wastes via the umbilical cord.

polygenic inheritance.

Occurs when a trait is a function of the interaction of many genes, such as with height, intelligence, and temperament.

prenatal care.

A set of services provided to improve pregnancy outcomes and engage the expectant mother, family members, and friends in pregnancy-related health care decisions.

prenatal development

The process by which a single cell develops into a newborn.

preterm.

A birth that occurs 35 or fewer weeks after conception.

sickle cell trait.

A recessive trait, most often affecting African Americans, that causes red blood cells to becomecrescent or sickle shaped, resulting in difficulty distributing oxygen throughout the circulatory system.

small for date.

Describes an infant who is full term but who has significantly lower weight than expected for the gestational age.

spina bifida.

A neural tube that results in spinal nerves growing outside of the vertebrae, often resulting in paralysis and developmental disability.

teratogen.

An environmental factor that causes damage to prenatal development.

triple X syndrome.

Chromosomal disorder in which an individual is born with three X chromosomes. Often unnoticed.

Turner syndrome.

Sex chromosome abnormality in which a female is born with only one X chromosome; girls with this syndrome show abnormal growth patterns, abnormalities in primary and secondary sex characteristics, and other disorders.

ultrasound.

Prenatal diagnostic procedure in which high-frequency sound waves are directed at the mother’s abdomen to provide clear images of the womb projected onto a video monitor.

very low birthweight.

Refers to a birthweight less than 1,500 grams (3.5 lbs.); poses risks for developmental disabilities and handicaps.

zygote.

A fertilized ovum.