Divided into three different stages: germinal, embryonic, and fetus.
(0-2 weeks) 60% of zygotes do not grow/successfully implant in uterus
(3-8 weeks) Approx. 20% aborted spontaneously (early miscarriage). Major organs develop and the organism is less than 2 inches long.
(9 weeks-birth) Approx. 5% aborted spontaneously before 22 weeks (age of viability) or are stillborn (born dead after 22 weeks). The sex organs develop and brain development is significant.
Only 31% of all conceptions result in live births.
When cells take on distinct characteristics and gravitate toward particular positions: shell (becomes placenta) and nucleus (becomes the embryo); still very fragile and tiny.
This organ (attached to wall of uterus) is the life-support system for the developing embryo and fetus, sustaining life via the umbilical cord.
The process, beginning about 10 days after conception, in which the developing organism burrows into the placenta that lines the uterus, where the organism can be nourished and protected as it continues to develop.
The third month
The fetus has all of its body parts. Weighs approximately 3 ounces and is 3 inches long. Fetus is too small/underdeveloped to live outside of the womb.
Fourth, fifth, and sixth months
The heartbeat becomes stronger. The cardiovascular system is more active, and the brain increases about six times its size.
Age of viability
Life outside of the womb is possible. If the child is born in the seventh month, it will require intensive hospital care and life-support systems.
Preterm vs. Newborn
Depends on the maturation of neurological, respiratory, and cardiovascular systems.
Agents and conditions, including viruses, drugs (medicinal and psychoactive), and pollutants/chemicals, that can impair prenatal development and result in birth defects or even death.
Agents and conditions that do not produce obvious physical defects but harm the prenatal brain, impairing the future child’s behavioral, intellectual, and emotional functioning (e.g., hyperactive, antisocial, learning-disabled).
The science of weighting the potential effects of a particular event, substance, or experience to determine the likelihood of harm.
In prenatal development, the time when a particular organ or other body part of the embryo or fetus is most susceptible to damage by teratogens.
A situation in which a certain teratogen is relatively harmless in small doses but becomes harmful once exposure reaches a certain level (the threshold).
The result of a combination of teratogens. Sometimes risk is greatly magnified when an embryo or fetus is exposed to more than one teratogen at the same time.