Heredity, Pre-natal Development, and Childbirth

• Study notes on heredity, pre-natal development, and childbirth

Definition of Terms

• Fertilization, also known as conception, is the process where sperm and ovum combine to form a zygote, which divides repeatedly
• Ovulation is the rupture of a mature follicle in an ovary, expelling an ovum, which occurs monthly until menopause
• Dizygotic twins, or fraternal twins, result from two separate eggs fertilized by two different sperm and can be different sexes, with a possible genetic basis
• Monozygotic twins result from the cleaving of one fertilized egg and are generally genetically identical
• Heredity refers to the genetic transmission of heritable characteristics from parents to offspring
• DNA is a spiraling ladder with steps made of pairs of chemical bases: adenine, thymine, cytosine, and guanine
• Chromosomes are coils of DNA that contain genes

Cell Division and Genetic Code

• Mitosis is cell division in non-sex cells
• Meiosis is cell division in sex cells
• Mutation is a mistake in copying genetic code, causing a permanent alteration
• Autosomes are not related to sexual expression
• Sex chromosomes are the 23rd pair, determining sex (XX for female, XY for male)
• Alleles produce alternative expressions of characteristics
• Homozygous means two alleles are the same
• Heterozygous means two alleles are different

Genetic Traits and Makeup

• A dominant allele is always expressed as a trait
• A recessive allele is usually not expressed unless paired with another recessive allele
• Polygenetic inheritance involves the interaction of several genes
• Phenotype refers to observable characteristics
• Genotype is the underlying genetic makeup
• Epigenesis is when the environment influences when genes turn on and off, where chemical molecules attached to a gene alter how a cell "reads" the gene's DNA, and cells are susceptible to epigenetic modification during puberty and pregnancy

Chromosomal Abnormalities

• Down Syndrome: extra copy of chromosome 21, treated with surgery and SPED
• Klinefelter Syndrome: extra X chromosome (XXY), treated with hormone therapy
• Fragile X Syndrome: abnormality in the X chromosome, causes intellectual disability, treated with SPED and speech therapy
• Turner Syndrome: missing X chromosome for females, treated with hormone therapy
• XXY Syndrome: extra Y chromosome, no treatment

Gene-Linked Abnormalities

• Cystic Fibrosis: Overproduction of mucus in the lungs and digestive tract, treated with physical therapy
• Diabetes: body doesn't produce enough insulin, treated with insulin
• Hemophilia: delayed blood clotting, treated with blood transfusions
• Huntington's: CNS disorder

Genetic and Environmental Factors

• Carriers carry one bad copy of a recessive gene and one good copy
• Genotype-environment interaction describes how similar environmental conditions affect genetically different individuals
• Genotype-environment correlation describes how the environment often reinforces genetic differences
  • Passive correlations in which parents tend to provide environments that encourage the development of that trait
  • Reactive or evocative correlations: children with differing genetic makeups evoke different reactions from others
  • Active correlations: actively selects or creates experiences consistent with their genetic tendencies
• Niche-picking is a tendency to seek out environments compatible with one's genotype
• Nonshared environmental effects occur due to the unique environment in which each child grows up
• Infertility is the inability to conceive a child
• In Vitro Fertilization is when eggs and sperm are combined in a laboratory dish

Prenatal Diagnostic Tests

• Ultrasound high-frequency sound waves directed into the pregnant woman's abdomen
  • No risk to woman/fetus
  • Detect abnormalities, number of fetuses, and sex
• Fetal MRI uses powerful magnet and radio images to generate detailed images of the body's organs and structures
• Chorionic Villus Sampling is when a small sample of the placenta is removed which has a small risk of limb deformity
• Amniocentesis is when a sample of amniotic fluid is withdrawn and tested for chromosomal and metabolic disorders
• Maternal Blood Screening identifies pregnancies that have an elevated risk for birth defects

Prenatal Development

• Gestation is the period between conception and birth
  • Between 37 and 41 weeks
  • Gestational Age is dated from the first day of an expectant mother’s last menstrual cycle

Stages of Prenatal Development

• Cephalocaudal principle says development proceeds from head to the lower extremities
• Proximodistal development proceeds from the center to outer parts of the body

Early Pregnancy Signs

• Tender, swollen breasts or nipples
• Fatigue
• Slight bleeding or cramping
• Food cravings
• Nausea with or without vomiting
• Frequent urination
• Frequent, mild headaches
• Constipation
• Mood swings
• Faintness and Dizziness
• Raised basal body temperature

Germinal Stage

• From fertilization to about 2 weeks of gestational age
• Zygote enters into cell division (mitosis) while traveling to the fallopian tube
• Differentiation specializes cells for various tasks
• Blastocyst is a fluid-filled sphere that floats in the uterus until the 6th day, then implants itself in the uterine wall
• Trophoblast is the outer layer of cells that later provides nutrition and support for the embryo
• Ectoderm is the outer layer that becomes the outer layers of the skin, nails, hair, teeth, sensory organs, and the nervous system
• Endoderm: inner layer that becomes digestive system
• Mesoderm is the middle layer that becomes inner layers of skin, muscles, skeleton, and excretory and circulatory systems

Embryonic Period

• Amniotic sacs enclose the developing embryo, protecting it and giving it room to grow
• Placenta allows passage of oxygen, nourishment, and wastes between mother and embryo
• Umbilical cord connects the embryo to the placenta
• Weeks 2-8 (first 2 months) of development
• Major body systems (respiratory, digestive, and nervous system) develop, or organogenesis
• Critical period is when one's most vulnerable to destructive influences
• Spontaneous abortion (miscarriage) is expulsion from the uterus of an embryo that is unable to survive outside the womb
• Stillbirth is miscarriage that occurred after ≈20 weeks gestation
• Males are more likely to be spontaneously aborted or to be stillborn

Fetal Period

• From 8 weeks to birth
• Appearance of the first bone cells
• Final gestation stage
• Rapid growth, around 20x its previous length
• Finishing touches
• Breathe, kick, and turn
• Facial expressions of pain at 36 weeks
• Responds to mother’s voice
• Fetuses know when they approach the near end of the pregnancy
• Grasping reflex
• At 6+ months, fetuses can survive outside the matrix
• 24-37 month babies need help in breathing

Environmental Influences

• Teratogen is an environmental agent that can interfere with normal prenatal development
• Caffeine has slightly increased risk for miscarriage, stillbirth, and low birth weight babies
• Rubella is almost certain to cause deafness and heart defects
• Toxoplasmosis is caused by a parasite that is in cattle, sheep, pigs and can cause fetal brain damage, severely impaired eyesight, seizures, miscarriage, etc.
• Diabetic mothers are likely at risk of having babies that have heart and neural tube defects
• Stress and anxiety has been associated with more irritable and active temperament in newborns
• Chronic stress can result in preterm delivery
• Depression may cause premature birth or developmental delays
• Chance of miscarriage or stillbirth rises with maternal age
• Adolescent Mothers tend to have premature or underweight babies
  • Air pollution, radiation, chemicals increase the risk of it happening
• Fetal exposure to low levels of environmental toxins may result to asthma, allergies, lupus
• X-rays could triple the risk of having full-term, low-birth weight babies

Paternal Factors

• Exposure to lead, marijuana, tobacco, radiation, pesticides, etc. may result in abnormal or poor quality sperm
• Exposure to diagnostic x-rays within the year prior to conception or high lead exposure at work tends to result in low birth weight and slowed fetal growth
• Older fathers may be a significant source of birth defects due to damaged sperm
• Results in deteriorated sperm as well- dwarfism, schizophrenia, bipolar disorder, ASD

Prenatal Care

• Prenatal cell-free DNA scans are given by extracting DNA from the mother's blood to detect problems early

Birth Process

• Labor is the process of giving birth
• Paturition is the series of changes that begins 2 weeks before delivery
• Braxton-hicks is false contractions
• Real labor has more frequent, rhythmic, and painful contractions which intensify

Stages of Birth

• Longest stage, contractions 15-20min, cervix opens 10 cm

Stage 2 of Birth

• Baby coming out
• Baby’s head starts to move through the cervix
• Averages around 45min

Stage 3 of Birth

• Afterbirth
• Shortest stage

Midwifery/Doula

• Midwifery helps with healthcare during the mother's pregnancy
• Doula provides emotional support from before until after the birth

Electronic Fetal Monitoring

• Used to track the fetus heartbeat and also how the heart responds during labor
• Can also provide valuable information during high risk delievers
• Potential to have false positives

Analgesia/Anesthesia and Natural Childbirth

• Uses three kinds of drugs- analgesia, anesthesia and oxytocin
• Natural childbirth aims to reduce mother's pain
• Bradley method husband's act as relation coaches
• Prepared childbirth teaches special techniques to push

Types of Delivery

• Vaginal- normal birth is the safest
• Cesarean delivery is an abdominal incision to remove the baby

Post Birth

• It's not recommended to deliver before 39 weeks because the baby would have immature lung defects
• Breech positon is when the baby is delivered out buttocks first, which can cause injury to the lungs

APGAR Scale

• Assesses how healthy the birth
• A score of 7-10 is good
• And everything under there are certain problems associated with it

Brazelton Neonatal Behavioral Assessment Scale

• Assesses neurological development
• Assess reflexes and reactions

Factors relating to babies

• Boys tend to be slightly longer and heavier
• First born weigh less than later ones
• Lanugo- fuzz pre natal hair
• Vernix caseosa- oily protection
• Preterm and low weight

Various Birth Conditions

• Low birth weight is below 5 pounds
• Extreme low birth weight is under 2 pounds
• Preborn are three weeks early

The Bonding System

• Bonding is the form of connection that happens after the birth
• The mother does have to come into constant with the baby to develop fully
• There are dramatic changes from the hormones
• Baby can expereince post partum and could affect the mother/child relationship

Explore heredity, pre-natal development, and childbirth, focusing on fertilization, ovulation, and twins. Understand cell division and genetic code transmission. Learn how mitosis and meiosis affect genetic diversity.