Characteristics of the Unborn Child
Growth and Development
In Oklahoma, the definition of Unborn Child (Title 63 O.S. §1-730)
means the unborn offspring of human beings from the moment of conception,
through pregnancy and until live birth including the human conceptus,
zygote, morula, blastacyst, embryo and fetus.
Physicians often refer to the gestational age of an unborn child as measured
from the first day of the last menstrual period (referred to as "LMP").
Another way the age of the unborn child is referred to is based upon the
number of weeks since conception (fertilization). Therefore, two (2) weeks
after conception corresponds approximately to four (4) weeks gestational
age (LMP). Some women have irregular periods and other methods can be
used to determine the age of the unborn child. For example, ultrasound
can be used to measure the length of the unborn child, which then can
help estimate the gestational age of the unborn child.
Conception begins when a womans egg is fertilized by the male sperm.
The union of the male sperm and female egg form a one-celled entity called
a zygote. The zygote has 46 chromosomes, 23 from the mother and 23 from
the father. Chromosomes contain genetic material that are the blueprint
for growth and development throughout life, determining physical characteristics
such as gender, the shape of the nose and ears, and the color of the hair,
eyes, and skin, facial features, and at least to some extent, intelligence
During the first 8 weeks following fertilization, the unborn child is
known as an embryo. After that time, the unborn child is known as a fetus
(Latin for offspring). During the first ten weeks of pregnancy, the unborn
child is most likely to be affected by things like:
- Nicotine in cigarettes or other tobacco products.
- Some prescription medicines or over-the-counter drugs (Consult with
your doctor before taking drugs of any kind).
- Illegal drugs (like heroin, cocaine, methamphetamine, marijuana,
- Viruses (such as rubella or cytomegalovirus).
- X rays, radiation therapy, or accidental exposure to radiation.
- Vitamin deficiencies (such as folic acid).
The development of an unborn child depends on many factors.
This booklet will discuss only normal growth and development. The gestational
stages photos and drawings are not meant to convey precise size and/or
detail, but rather the general shape and progression of the unborn child
as he or she develops.
Ages in this website are listed as both the estimated
day when conception (fertilization) occurs and from the first day of the
last normal menstrual period (LMP).