Download Three main periods of prenatal development

Chapter 2 – Genes and Prenatal Development
From Zygote to Newborn
Three main periods of prenatal development
1.
2.
3.
Germinal Period (first two weeks after conception): rapid cell
division and beginning of cell differentiation
Embryonic Period (3rd through 8th week): basic forms of all body
structures develop
Fetal Period (9th week until birth): fetus grows in size and matures in
functioning
Birth
 Fetal brain signals the release of hormones to trigger the
female’s uterine muscles
 Labor begins
 Apgar scale
Traditional and Modern Birthing
Practices
 Home births
 Hospital births
 Doula
Cesarean Section (C-Section)
Surgical birth
Fetus can be removed quickly
Rates and reasons for c-sections vary greatly
Less trauma for the newborn but slower recovery for the
mother
 Subsequent cesarean deliveries may be necessary
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Siblings and Twins
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Sibling Similarities

Monozygotic (identical) twins:
Siblings and Twins
 Dizygotic (fraternal) twins
Causes of Low Birthweight
 Genetic factors
 Maternal illness
 Exhaustion
 Infection
 Malnutrition
 Drug use
 Multiple births
Prenatal Teratogens
 Substances and conditions that can impair prenatal
development and result in birth defects or even death
 Not all teratogens can be avoided
 Structural abnormalities are obvious at birth
 Behavioral teratogens
Significant Factors
1.
2.
3.
Genetic Vulnerability
Timing of Exposure
Amount of Exposure
Resolving Uncertainties
 Pregnancy does not have to be an anxious time
 Good prenatal care can
 teach women what they can do to have healthy babies
 save lives
 reassure parents that all is well