Chapter 2 – Genes and Prenatal Development

From Zygote to Newborn Three main periods of prenatal development 1. Germinal Period (first two weeks after conception): rapid cell division and beginning of cell differentiation 2. Embryonic Period (3 rd through 8 th week): basic forms of all body structures develop 3. Fetal Period (9 th 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

Siblings and Twins 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. Genetic Vulnerability 2. Timing of Exposure 3. 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