Prenatal Development, Pregnancy, and Birth Chapter 2 Prenatal Development, Pregnancy, and Birth

Female reproductive system Uterus Fallopian tubes Ovaries Ova are in the ovaries and contain mother’s chromosomes

Male reproductive system Testes continually manufacture sperm Penis

Fertilization Ovulation ovum ejected from Ovary and moves into fallopian tube Millions of sperm travel up fallopian tube to the ovum (they live 7 days) Fertilization Only one sperm penetrates ovum Genetic material of male and female combine

Genetics 23 chromosome pairs (contain DNA) 23 each from mother and father Sex chromosomes join in only one pair (XX for female child, XY male) Genes are on chromosomes, act like blueprint of the developing individual

Prenatal Development Proximodistal Cephalocaudal Mass to specific Growth from mid-inside out Cephalocaudal Growth from head to foot (tail) Mass to specific Large structures, then fine features Large movement, then fine movement

Prenatal Stages Germinal (zygote) Embryonic Fetal First 14 days 3rd to 8th week Fetal 9th week to birth

Embryonic Stage Proximodistal and cephalocaudal

Fetal Stage Age of viability 22 weeks, earliest date for survival outside the placenta Birth weight is important Baby needs as much time in the womb as possible – in last two months the fetus gains 5 pounds

Teratogens Substances that cross the placenta and harm the embryo or fetus: Medication (thalidomide) Disease (Rubella) Social drugs (alcohol, nicotine, marihuana, cocaine) Environmental (pesticides, radiation) Stress (effects of hormones)

Effects of teratogens Most damage during sensitive periods Structural damage in embryonic period Can affect brain throughout pregnancy Developmental disorder risk highest in 2nd to 3rd trimester Dose-response effect (threshold level) May act long after exposure

Effects of nicotine and alcohol Constricts blood vessels Increases risk of smaller less healthy babies Alcoholism Risks Fetal Alcohol Syndrome (FAS). Know the symptoms!

Chromosomal Disorders 46 chromosomes interact in 23 pairs If a chromosome is missing or extra the embryo may miscarry An extra chromosome 21 causes Down syndrome (trisomy 21). Was called “Mongolism!“ and “Mongoloid idiot”

Single-gene disorders Genes are on chromosomes and determine specific traits Most traits depend on many genes but single gene disorders occur when there is a defect in only one gene. Three heritability modes: Dominant or recessive gene Sex-linked gene

Genetic Counseling Genetic Counselors Genetic Testing Counsel couples about their own or child’s risk of genetic disorders Give advice about available treatments Help couples make a decision Genetic Testing Blood test determines whether a person carries a gene for a genetic disorder

Prenatal Tests Ultrasound Dates pregnancy and charts fetus growth but can reveal structural abnormalities. Chorionic Villus Sampling During 1st trimester, piece of developing placenta tested for genetic conditions. Amniocentesis 2nd trimester, tests amniotic fluid for genetic conditions. Has some miscarriage risk.

Birthing Stage 1: Dilation and effacement (crowning) Stage 2: Birth Stage 3: Expulsion of placenta Threats: breech position, cervix not fully dilating, difficult position of umbilical cord

Birth Options Natural childbirth Cesarean No medication, help of midwife or doula Bradley, natural, no medication Lamaze pain management Sometimes medical intervention is needed. Cesarean More common in some countries Used if there are complications

The neonate (newborn) Apgar Scale: first test after birth, scored 0, 1, 2 in five categories, at one and five minutes after birth. Over 7 is healthy. Skin color Muscle Tone Respiration Heart Rate Reflex Response

Threats to Development Low Birth Weight Body weight less than 5½ lbs. Arrived too early or delayed growth Very low birth weight Weighs less than 3¼ lbs. If very premature, treated in neonatal intensive care unit

Infant Mortality Measure of a nation’s overall health care U.S. ranks 41st. Some reasons are poverty and inadequate access to prenatal care Socioeconomic status (SES) affects healthcare across the life span.