Webster's New World Medical Dictionary

pregnancy, ectopic
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prenatal care
Health care that a pregnant
woman receives from an obstetrician or a midwife.
Services needed include dietary and lifestyle advice,
weighing to ensure proper weight gain, and exami-
nation for problems of pregnancy such as edema
and preeclampsia. 
prenatal development
The process of growth
and development within the womb, in which a sin-
gle-cell zygote (the cell formed by the combination
of a sperm and an egg) becomes an embryo, a fetus,
and then a baby. The first 2 weeks of development
involve simple cell multiplication. This tiny mass of
cells then adheres to the inside wall of the uterus.
The next 3 weeks see intense cell differentiation, as
the cell mass divides into separate primitive sys-
tems. At the end of 8 weeks, the embryo takes on a
roughly human shape and is called a fetus. For the
next 20 weeks the fetus’s primitive circulatory, nerv-
ous, pulmonary, and other systems become more
mature, and the fetus begins to move its limbs. At 28
weeks, fat begins to accumulate under the skin, toe-
nails and fingernails appear, and downy hair sprouts
on the body and scalp. The fetus may open its eyes
periodically. For the remaining weeks of develop-
ment, the fetus continues to gain weight, and its
internal systems reach full development.
prenatal diagnosis
Diagnosis before birth.
Methods for prenatal diagnosis include ultrasound
of the uterus, placenta, and/or developing fetus;
chorionic villus sampling (CVS) to obtain tissue for
chromosome or biochemical analysis; and amnio-
centesis to obtain amniotic fluid for the analysis of
chromosomes, enzymes, or DNA. A growing number
of birth defects and diseases can be diagnosed pre-
natally and in some cases treated before birth. Also
known as antenatal diagnosis.