Fertilization, Twins, Genetic Code

• Details for the processes behind forming a new life

Fertilization

• Fertilization is the process where sperm and ovum (male and female gametes or sex cells) combine
• The result is a single cell named a zygote
• A zygote is the one-called organism that results from fertilization

Multiple Births

• Dizygotic twins are twins conceived via the union of two different ova with two different sperm cells
• They're also called fraternal twins and are genetically no more similar than any other siblings
• Monozygotic twins result from the division of a single zygote after fertilization
• They're also called identical twins and are genetically similar, forming from the cleavage of on fertilized egg

Genetic Code, DNA, and Chromosomes

• Deoxyribonucleic Acid (DNA) is a chemical that carries inherited instruction for cellular development
• Genetic code refers to the sequence of bases within the DNA molecule
• It governs the formation of proteins that determine the structure and function of living cells
• Chromosomes are coils of DNA that consists of genes

Genes and Inheritance

• Genes are small segments of DNA located on particular chromosomes
• They're functional units of heredity
• The human genome refers to the complete sequence of genes found in the human body
• Mutations are permanent alterations in genes and/or chromosomes
• Results can be harmful characteristics
• Alleles are two or more alternative forms of a gene
• They occupy the same position on paired chromosomes and affect the same trait
• Autosomes are the 22 pairs of chromosomes in humans not related to sexual expression
• Sex Chromosomes are the pair of chromosomes that determines sex
• XX in the normal human female, XY in the normal human male
• Homozygous traits possess two identical alleles
• Heterozygous traits involve possessing differing alleles
• Dominant inheritance is the pattern of inheritance in which only the dominant allele is expressed when a child receives different alleles
• Recessive inheritance is the pattern of inheritance in which a child receives identical recessive alleles
• It results in the expression of a non-dominant trait
• Polygenic inheritance follows the pattern in which multiple genes at different sites on chromosomes affect a complex trait

Phenotype and Genotype

• Phenotype refers to the observable characteristics of a person
• Genotype refers to the genetic makeup of a person, containing expressed and unexpressed characteristics/ -"Your genotype is the recipe for making you. Your phenotype is how you actually turn out"
• Epigenesis is the mechanism that turns genes on or off and determines the functions of body cells

Incomplete Dominance and Sex-Linked Inheritance

• Incomplete dominance is the pattern of inheritance in which a child receives two different alleles
• This results in partial expression of a trait
• Sex-linked inheritance is the pattern of inheritance in which certain characteristics carried on the X chromosome inherited from the mother are transmitted differently to her male and female offspring

Turner and Down Syndrome

• Children with Turner Syndrome are always girls as little information is carried on the Y chromosome
• An embryo with only a Y chromosome and no X chromosome is not viable
• An embryo with an X chromosome, but no Y, often is
• Down Syndrome is a chromosomal disorder characterized by moderate-to-severe mental retardation and physical signs such as a downward-sloping skin fold at the inner corners of the eyes
• Also called trisomy-21
• Another sign includes a single palmar horizontal line

Behavioral Genetics, Heritability, Concordance, and Genetic Counseling

• Behavioral genetics are the quantitative study of relative hereditary and environmental influences on behavior
• Heritability is the statistical estimate of heredity's contribution to individual differences in a specific trait within a given population
• Concordant describes the tendency of twins to share the same trait or disorder
• Genetic counseling is a clinical service that advises prospective parents of their probable risk of having children with hereditary defects
• Note high heritability doesn't mean a trait can't be influenced by the environment
• Environmental changes can alter heritability estimates
• Reaction rate refers to potential variability in a hereditary trait's expression dependent on environmental conditions
• Canalization illustrates how heredity restricts the range of development for some traits
• Genotype-environment interaction refers to the effects of similar conditions in genetically different individuals

Genotype-Environment Correlation

• Passive correlation refers to children learning specific things that are present in their home
• Reactive correlation involves children learning specific things that were taught and presented to them
• Active correlation encompasses the children picking or having the freedom to choose their own activities

Characteristics Influenced by Heredity and Environment

• Obesity means there is a 2-3x higher chance of a child developing obesity with a family background
• Heredity exerts a strong influence on general intelligence
• Measured by intelligence tests with a moderate effect on specific abilities
• Temperament and personality refers to a baby's unique and characteristic ways of approaching and reacting to the environment
• Schizophrenia illustrates the interaction of heredity and genetics
• It is a neurological disorder characterized by loss of contact from reality

Prenatal Development

• Prenatal development takes place in 3 stages: germinal, embryonic, and fetal
• During these three stages a single-celled zygote grows into an embryo and then a fetus
• The cephalocaudal principle dictates that development proceeds from the head to the lower part of the trunk
• Growth and motor development occur from the top down and from the center of the body
• The germinal stage takes place from fertilization to 2 weeks
• The zygote divides, becomes more complex and implants in the wall of the uterus
• The embryonic stage occurs from 2-8 weeks
• Organs and major body systems such as the respiratory, digestive, and nervous systems develop rapidly
• This process is known as organogenesis
• The stage is a critical period where the embryo is most vulnerable to destructive influences
• Most defective embryos usually don't survive the first trimester
• The fetal stage takes place from 8 weeks to birth
• First bone cells appear around 8 weeks signaling the beginning of the fetal stage
• The fetus grows rapidly to 20x its previous length, body system complexity increases
• "Finishing touches" like fingernails, toenails, and eyelids continue to develop

Prenatal Care

• Noninvasive procedures that use of ultrasound and blood tests are progressing to detect chromosomal abnormalities
• A combination of three noninvasive tests at 11 weeks of gestation predicted Down Syndrome presence with 87% accuracy

Environmental Influences & Maternal Factors

• The environment is the mother's body
• Has influence over well-being, diet and mood
• A teratogen is an environmental agent like a virus
• Drugs or radiation can interfere with prenatal development
• Nutrition and maternal weight for pregnant needs 300-500 calories per day
• This includes extra protein
• Women with 16-40 pound gains are less likely to have birth complications or low birth weight babies
• Malnutrition is a global problem caused by poverty, conflict and climate change
• Can cause expectant mothers to suffer calorie deficit resulting in fetal growth restriction and low birth weight
• Moderate exercise during pregnancy doesn't endanger a healthy woman's fetus
• Regular exercise prevents constipation and back pain
• Everything an expectant mother takes makes its way to the uterus
• Drugs cross the placenta like oxygen, carbon dioxide and water
• Medical drugs can be harmful during pregnancy, especially antibiotics like tetracycline and certain barbiturates/opiates that are central nervous system depressants
• Opioids are associated with small babies and fetal death
• Alcohol is a common cause of intellectual disability and birth defects
• Nicotine (from maternal smoking) is identified as the most important factor in low birth weight in developed countries
• Under 300 milligrams of caffeine daily isn't associated with miscarriage
• Marijuana isn't associated with birth defects
• Methamphetamine causes preterm delivery and low birth weight
• Cocaine causes spontaneous abortion, delayed growth, premature labor, low birth weight, and birth defects

Prenatal Care Across the World

• The UN estimated about 130 million babies were born worldwide in 2018
• 830 women die each day from childbirth-related complications
• 99% of these deaths occur in low resource areas
• Hemorrhage, hypertensive disorders, and infection are responsible for over 50% of all maternal deaths
• Prevention relies on education and prenatal care

Other Influences

• Physical activity doesn't seem to endanger a healthy woman's fetus
• Exercise prevents constipation/reduces back pain and may reduce risks of gestational diabetes, preeclampsia
• Some anxiety/stress/depression during pregnancy is normal
• Doesn't increase risks like low birth weight
• Moderate maternal anxiety may spur organization in the developing brain

Birth and Physical Development During the First Three Years

Childbirth and Culture

• Customs surrounding childbirth reflect a culture's beliefs, values, and resources
• Historically childbirth was struggle with death, but hospital/medical advancement reduced mortality
• Childbirth isn't risk-free
• Developed countries see complications/developing regions have women giving birth without skilled care
• Maternal deaths have declined 44% since 1990
• A small percentage of women in developed countries are choosing home births
• Hospitals are humanizing childbirth with birthing rooms and rooming-in policies

The Birth Process

• Labor brings on a series of uterine, cervical, and other changes called "parturition"
• Parturition is giving birth, typically begins about 2 weeks before delivery
• Uterine contractions expel the fetus about 266 days after conception
• Labor contractions are rhythmic and painful
• Increase in frequency and intensity compared to relatively mild, irregular Braxton-Hicks contractions

Stages of Childbirth

• During Stage 1 (dilation of the cervix) the process lasts 12-14 hours for first-time mothers
• Contractions widen the cervix to 10cm
• During Stage 2 (descent and emergence of the baby) lasts up to 2 hours ending when the baby is born by is still attached to the placenta
• During Stage 3 expulsion of the placenta lasts 10 minutes to 1 hour
• The placenta and umbilical cord are expelled

Monitoring

• Electronic Fetal Monitoring can track a fetus' heartbeat during labor and indicate how the fetal heart is responding to contraction stress
• EFM restricts movement and is costly/high false-positive rate

Vaginal Verses Cesarean Delivery

• Vaginal delivery is typical, cesarean delivery is used with complications
• US cesarean rates peaked in 2009 carry risks/deprive babies birth benefits
• VBAC (vaginal birth after cesarean) is a 60-80% success rate

Labor Pain

• Pain was once considered unavoidable in childbirth
• Sedation became common in the mid-19th century
• Techniques in Natural Childbirth/Prepared Childbirth were developed to minimize drugs/involve both parents

Pain Reduction

• Many mothers choose local anesthesia, analgesics, or epidurals to block pain
• May slow labor and pose risks to baby
• 71% women receive epidurals/spinal anesthesia
• Doulas provide emotional support
• Improve birth outcomes and reduce costs
• Costs aren't always covered by insurance

New Born Baby

• The neonatal period is the first 4 weeks of life, transition from uterus (where a fetus is supported) to independent existence
• Average neonate is 20 inches/7.5 pounds (boys are slightly longer/heavier) in the US
• Lose 10% weight initially, regain it by days 10-14
• Large head, receding chin, fontanels for skull flexibility
• Thin/pinkish skin, lanugo/vernix caseosa for protection
• Swollen genitals or temporary, hormone-related breast swelling

Body System

• Mother's body handles circulation, respiration, nourishment, waste elimination, and temperature regulation before birth
• Functions are taken over by the baby with most adjustments occurring in 4-6 hours
• Neonate starts breathing at birth, Anoxia (lack of oxygen) can cause brain damage
• Excrete meconium and digest milk instinctively
• Regulate temperature through body fat/activity
• 50% babies develop Neonatal Jaundice (liver immaturity), usually harmless or potentially serious if untreated

Assessment

• Crucial to detect problems in the first minutes, days, and weeks

The Apgar Scale

• 0-10 points assessed 1 and 5 minutes on appearance/pulse/grimace/activity/respiration
• 7-10 indicates good health
• <4 needs immediate lifesaving

Assessment Tools

• Brazelton Scale : evaluates a newborn's motor function/reflexes/irritability/alertness/nervous system stability within 30 minutes to predict future development
• Neonatal Screening - tests for rare conditions like PKU, congenital hypothyroidism, and galactosemia

State of Arousal

• The babies have internal biological clocks regulate states of arousal - wakefulness, sleep, and activity
• Inborn/individual, linked to newborn health
• 0-2 months= 14.5 hours sleep a day/ 1..7 waking times per night/ 3 hours of daytime naps.
• 2 months - longest nightly sleep (5.7 hrs) to (8.3 hours) at 6 to 24 months.
• 1 year- Sleep 12.6 hours a night/ 0.7 waking
• 2 years- Sleep 13 hrs, including naps.
• REM sleep - 50% newborn sleep
• 3yrs= Decline less than 30%

Sleep Schedules

• Vary by culture
• Micronesian Truk=no set patterns
• Australia/New Zealand bedtimes= 7:43 PM
• India 10:26 PM
• Rural Kenya= four-hour stretches
• Predominantly Asian countries= later bedtimes, total sleep is shorter than in predominantly Caucasian countries.

Children Sleep Problems

• Young children get similar total sleep over 24 hours by adjusting naps.
• Sleep problems are common that insufficient infant sleep is linked to later attention and behavioral issues.

Developmental Complications

• Although great majority of births results in normal/healthy babies, problems can occur
  • Babies can be prematurely/very small/ remain in the womb too long, or are born dead/die soon after birth

Low Birth Weight

• Low birth weight babies (LBW) are neonates born under 2.500 grams (5pounds) at birth.
• Two types of LBW babies - those born early or are small .
• Gestation is 40 weeks
• <37th week gestation = preterm/premature infants

Risk Factors for Low Birth Weight

• Factors increase risk of underweight baby include being African/ American under age 17 or over 40
• Poor, unmarried/under educated, and certain regions/states

Immediate Treatment and Outcomes for LBW

• Premature babies have not fully developed the immune system
  • Particularly vulnerable to infection/nervous system may be too immature for survival needs
• Most pressing fear is early death
• May potentially be subjected to invasive medical procedures

Long-Term Outcomes for LBW

• Trials may not be over, even if live dangerous early days
• Great risk for adverse health outcomes when compared to adult, who were born full term

Post Maturity

• Postmature babies tend to be long/thin because they have kept growing in the womb
• Babies lack sufficient blood supply toward gestation end
• Birth complication issues stem primarily related to being born early or too small, however, babies can be also negatively affected by staying too long in the womb.
• Incidence of post term pregnancy in US =5.5

Still Birth

• Fetal death after>20-week gestation
• Diagnosed prenatally or during labor/delivery

Survival and Health

• Infancy and toddler are risky for survival
• Many babies dying during the first year can be contributed by a lack of health

Infant Mortality

• Declined but remains uneven

Leading Causes of Infant Mortality

• Leading causes involve preterm birth complications (35%), childbirth complications (24%), and sepsis (15%), often due to poverty, poor maternal health, infection, and inadequate medical care.
• Maternal mortality remains high, with 303,000 deaths per year, mostly from hemorrhage (27%), preexisting conditions, and unsafe abortions.
• About two-thirds occur during the immediate postnatal period increasing infant mortality risk in the United States.
• Infant mortality rate fell from 100 per 1,000 in the twentieth century to 5.87 in 2017, but remains higher than in 44 other countries, mainly due to preterm births and low birth weight

Racial and Ethnic Disparities

• Infant Mortality Rate fell from 47 percent in 1940 to 5.87 percent in 2017.
• Black babies (11.76 percent) face 2x white/Hispanic rates.
• Native American and Alaska Native infants higher rates due to SIDS/alcohol syndrome.
• Obesity and cardiovascular disease vary across racial and ethnic groups contributing to disparities
• Smoking and alcohol consumption in Native Americans and Alaska Natives
  • Health care access/insurance disparities further increase risks, particularly for Hispanic/Latino adults.

Sudden Infant Death Syndrome

• Cause of infant death unexplained where the cause remains
  • SIDS accounts for 6.5 percent of infant mortality rates/peaks 2 and 4 months
• Common among African Americans/low-birth-weight/preterm babies/twins or triplets
• Babies with young mothers/previously had three or more children/have high blood pressure/late/no prenatal care
• Smoke exposure (either during pregnancy/birth) is key risk factor
  • Triple Risk model suggests: a vulnerable infant, a critical period, and an exogenous stressor
  • Genetic mutations affecting heart involved 14%
• Some infants have brain stem defects affecting breathing/heartbeat/body temperature/arousal/waking up when breathing stale air
• Reduced serotonin levels may also increase risk
• The potential environmental trigger in SIDS is often sleeping on stomach
• SIDS rates declined >50 after "Back to Sleep" campaign
• Recommendation is separated surface in parent's room/avoid soft bedding/smoke/pacifiers
• Potentially breastfeeding/immunizations may also offer protection

Causes of Infant Death

• Fifth leading cause of death in infancy in the United States are Injuries
• Second highest rate from unintentional injuries with 2/3 of injury deaths the 1st year involving suffocation
• Non-fatal injuries major cause of falls in infancy and toddlerhood with boys are more likely to be injured
• Those dying from accidental injuries often comes from African American, American Indian, and Alaskan Native ethnicities
• 90% of injury deaths are suffocation/MVA/drowning/residential fires/burns
• Often happens at home, caused by caregivers
• Baby-proofing helps prevent avoidable accidents

Immunizations for Better Health

• Measles, pertussis and polio are largely preventable worldwide 85% of children million routinely vaccinated
  • Prevents million deaths annually
  • But >20 million children under age 1 did not get vaccinations, due to conflict countries where health disrupted.

Early Childhood Vaccinations

• Over 90% of 19-35 month-olds receive US childhood vaccinations
  • But lower income/African American children can miss out and concerns exist about connection autism, studies show no link
  • Vaccine refusals/ international travel results 1,200 measles cases across 30 states 2019

Early Physical Development: Growth Factors

• Early childhood involves growing up healthy
• Principles include typical growth patterns
  • Involves sensory and motor abilities develop

General Development

• Development principles follow cephalocaudal/proximodistal:
• The brain grows quickly before birth so newborn baby is disproportionately large - the lower body develops more, and sensory- and motor- development follows.
• Infant physical development happens in stages such as arm grasping, head control, sitting, and walking.
• Internal trunk develops before arms/legs/hands/feet/toes - during infancy/early childhood the hands/feet grow faster.
• Babies learn bodies close to the center before the outermost parts. They learn their arm controls for reaching with hands for scooping/pincer grips.

Growth Patterns

• During child development grows fast in 1st 3 years particularly 1st few months
• By 5 months - Baby boy 16 pounds
• By 1 year- has more than tripled to have 25 pounds
• Rapid tapers off during the second/3rd years
• By B2 - Gain 5 1⁄2 b-day and 3 more pounds with 34 pounds
• A boy's height increases 10 inches 1st year, then 5 inches during 2nd year and increases 2 1⁄2 inches in the 3 years.
• Genes infant inherits that influence height/body type while nutrition and living conditions are genetics
• Children larger/maturing earlier >1 century earlier likely better nutrition, sanitation, sanitation

Growth Teeth Stages

• Teething usually begins around 3-4 mos, infants begin grabbing objects for mouth/5-9 mos 1st tooth appearance
• 1-year-old babies have 6-8 teeth
• Two-and-a-half-year-olds babies around teeth

Child Nutrition

• Proper nutrition is essential to grow healthier
• The recommendation is breastfeeding is always best and should continue for < year. AAP- exclusive breastfeeding is 6 mos or more - > that means fewer infant deaths, saving billion annually Social factors- most use formula, the only acceptable alternative Breastfeeding is inadvisable for Moms who test positive for (AIDS, TB, has safe-drugs or exposure Babies should consume only milk/non-or fortified formula (6 mos) while Iron-enriched solid foods-introduce gradually

Other Child Nutrition and Brain Development

• Not consuming recommendations- 17% babies receiving solid good months, drinks juice months, cow's milk months
• Most lack vegetables
• Infants and Babies-weight above the height. Obese from months to
  • Indians /Latinos Risk =high, weight gains, higher birth weights exposure
• Preventing by eating early
• More infants/communities lack

Brain and Reflex

The newborn-respond nipple. Fluid intake, nervous system, brain back bones Sensory=brain/body - and motor

Building the Brain

• Lifelong to emotional/cognitive. Brain at birth is almost adults Continues fit sizes 3 week= Conception, from tubes with spherical/birth is cord

• Cerebellum grows in 1 year.

• Cerebum is divided/hemisphere functions = lateralization

• Corpus=share messages function

• Cerebral=4

• Neurons cells/neurons brain=information

• Glia (protect neurons

• 2 months gestation =produced

• Neurons are formed brain 100

Memory and Function

• Neurons connections structures that producing/removing
• Glia pathways with enabling signals/ begins
• Half of adolescence
• Sensory pathways= motor pathways
• About year
• Auto =automatic. About major
• Primitive= survival
• Postural= voluntary 6-12
• Early function, remain functions
• The connection, environmental influences/ adaption

Plasticity Connections

• Learning abilities /
• Harmful, neural damage/aids

Early Experiences

• Can aid/mitigate some cognitive

Sensory Capacities

• Regions that controlling that grow enabling
• Well during, that- touch -feel

Touch and Pain

• Is 32 weeks . parts-touch.more solution'

Taste Smells

• Transfer to/exposures
• Likely tastes/toxins