Chapter 3: Prenatal Development, Birth, and the Newborn

cephalocaudal

"head to tail" growth and development of the brain/head and then growing downward

Fetal Alcohol Spectrum Disorder (Fetal Alcohol Syndrome)

(FASD) facial deformities and mental disabilities. Level of effects depend on dose and timing. *leading cause of mental retardation in Western Hemisphere

Three stages of prenatal development

(conception) germinal period, embryonic period, fetal period

germinal period

(conception)-first two weeks -fertilized egg/zygote divides -blastocyst forms -secretion of hormones that prevent menstruation ends at implantation to the uterine lining and establishment of early placenta and circulation supply -approx 2 weeks gestation -pregnancy is established

Rubella

(german measles) a viral disease with mild effects in older children and adults but can be devistating to developing fetus. *woman infected in first trimester have 50% change of having baby with defects (deafness, cataracts, heart, urinary, intestinal, and bone)

HIV

(human immunodeficiency virus) causes AIDS (acquired immunodeficiency syndrome) symptoms include pneumonia or meningitis.

prematurity survival rates

-2 pounds or less (10% in 70s, 45% today) (24 weeks 56% survive, 25 weeks 70% survive) *leading cause of neonatal death

problems and complicaitons

-failure to progress (relates to birth-something slows down in process) -breech (5%) -prematurity (before 37th week) -postdate (past 40 weeks) -twins/multiples (born 3 weeks early) -low birth weight

cesarean section

-high birth weight -not in correct position -baby or mom in medical distress -multiple babies -difficult labor

Possible consequences of prematurity

-infections -respiratory distress (immature lungs) -brain hemorrhages -feeding/sucking immaturity -developmental delays -neurological impairments -cognitive delays, ADHD

how to monitor health of baby

-mothers weight -ultrasound -triple screen test (blood test between 15th and 20th week)

causes of premature birth

-multiple births -young maternal age -maternal infection -many births close together -SES (malnourishment, exposure to toxins)

benefit to vaginal delivery

-stress hormones thought to prepare fetus for life outside the womb-helps produce surfactin - allows lungs to function well -c-section babies often have breathing difficulties -hormonal surge puts newborn in state of alertness; increase metabolic rate, increases blood flow

assessing the newborn

-suction nose and mouth -clean up (vernix caseosa) -measure weight length

two major changes in the first two weeks of embyronic period

1. formation of the neural tube 2. development of the primitive cardiovascular system.

three stages of labor

1. longest stage (about 20 hours) -uterine contractions (cervix dilates to 10cm) three sub stages: early (latent) to active to transition contractions getting longer, stronger, closer together 2. pushing and birth (15 min to 3 hours) -pushing baby through the birth canal 3. afterbirth (5-20 min) -placenta delivered

two ways mothers can pass diseases to their babies:

1. through the placenta 2. during the birth process

3 where and four who of birth

1.hospital 2.home 3.birth center 1.physicians 2.certified nurse midwives 3.doulas 4.lay midwives

movement during fetal period

14-20 weeks there is a lot of room to move around. Later on, it gets less roomy but they still move their faces and flutter around. *Rat injection test showed that fetal movement is crucial for healthy development.

when teratogens will most likely result in spontaneous abortion

2-8 weeks

% of miscarriages

20-30%

Weight and Length during Fetal Period

3 months: 3oz 3in (facial features) 4 months: 6oz 6in (kicking, heart beats) 5 months: 1lb 12in (finishing touches) 6-8: (sex differentiation) 7 months: 3lb 16in (all organs functioning)

embryonic period

3-8 weeks after fertilization. begins with implantation; blastocyst now referred to as embryo -placenta develops -very critical stage of development

what percent of zygotes successfully implant?

30%

fetus "practicing" sensory abilities

3rd month: swallow amniotic fluid and has primitive taste buds (get used to mothers milk) breathe amniotic fluid in and out of lungs, and crying when disturbed. touch one of first senses to develop

characteristics of 6th and 7th month

5th: vestibular system of middle ear functional 6th: can hear and see 7th: have sleep cycles

what percentage of birth defects are thought to be primarily caused by environmental factors.

7-10%

fetal period

9 weeks until birth -more rapid brain development -begin to see organs of motor, sensory and learning behavior

APGAR

A(ppearance (skin color) P(ulse) G(rimace) (reflexes) A(ctivity) (muscle activity) R(espiration) (breathing) on a scale from 0-2 and add them up *good range from 7-10 (concerning at below 6)

when do twins come about?

During the germinal period (end of the first week) twins develop own amniotic sac but share single chorion and placenta. However, less commonly twins divide during the two to eight cell phase where they have their own of everything.

Trimesters of pregnancy

First Trimester: conception-3 months germinal/embriotic Second Trimester: 3-6 months (cell differentiation) Third Trimester: 6-9 months baby gaining weight Birth around 38-40 weeks (266 days)

classic example of teratogen (Thalidomide)

Thalidomide given to mothers for morning sickness- later realized that it caused problems in limb formation when taken during specific time in gestation

First organ system to develop and when

The circulatory system. Day 21-22 when heart starts beating. Baby needs nutrition and oxygen

resilience

ability to resist negative outcomes from risk factors. researchers often discuss "resilience factors" and try to quantify risk and resilience factors and try to quantify risk and resilience. Take person first approach

programmed death of neurons

about 50% of all neurons in development die to set up an efficient information processing system

Implantation of embryo

after blastocyst makes contact with uterus, it buries deep into uterine wall and becomes attached

B-complex vitamin folic acid

aids in developing neural tube correctly- supplemented in diet

what occurs during embryonic period?

all major organs and body parts are established in rudimentary form and cells differentiate *most fragile period of development because everything is getting made and moms might not be aware they are pregnant and engage in risky activity.

teratogen

an environmental agent that disrupts the normal process of prenatal development

cephalocaudal

areas near the head develop at a more rapid pace than those farther away

preterm birth

before 37 weeks (more common with teenage mothers or moms over 35, low income, African american, and women who have had preterm births before)

neuronal migration

beginning at six weeks-6 months. neurons move from the center of the neural tube outward to form the brain, either sliding up long fibers extended from the glial cells or moving laterally on their own (completed by 7th month)

blastocyst

bundle of cells formed four days after fertilization. Outer cells form structures that sustain embryo, inner cells form embryo.

Neurons

cells in the brain that send and retrieve information *start being produced in 5th week in the embryonic period in a process called neurogenesis

inner cell mass

cells inside the blastocyst that form the embryo

developmental programming

changes in the physiology of the fetus from environmental stimuli during sensitive periods of prenatal development that result in long-term changes in health.

Cigarettes as Teratogen

contribues to: -low birth rate -decreased placental blood vessel size (decreased nutrient transfer between mother and fetus) -13% of pregnant women smoke (2008)

chemical process for how birth initiates

cortisol released which cuases mother's pituitary gland to release oxytocin (initiates uterine contractions)

proximodistal

developing from the center outward

heterochrony

different cells undergo mitosis at different rates

four things that affect impact of teratogen

dose-higher concentrations are worse genes- can respond better or worse cumulative effects- more than one kind timing of exposure- when in development are they exposed sleeper effects- effects that aren't seen right away

lanugo

downy hair on baby at 5 months

three primary germ layers (start to form third week after conception)

ectoderm (nervous system, sensory organs, skin, nails, hair, teeth) mesoderm (circulatory and excretory systems, muscle, bones) endoderm (respiratory and digestive systems)

How sexual differentiation occurs

either the SRY gene on the Y chromosome turns on and instructs one set of structures to form the testes, which produce testosterone and kill the female structures, or the lack of testosterone in females causes the male structures to die and female structures to develop.

in vitro fertilization (IVF)

fertilization occurs outside mother and inserted.

exposure to teratogen during germinal, embryonic, and fetal stages

germinal: probably die off embryonic: affect development of major organs and body parts fetal: fewer structural and physiological defects but still damage

three germ layers

indoderm, mesoderm, exoderm (layers of the blastula)

benefit to using midwives

less likely to use fetal monitoring or induce labor

Neural Tube Formation

lines baby's back and head. Closes to form brain on top end. Can result in Neural tube defect (anencephaly: tube doesn't close so brain doesn't develop or spina bifida: tube doesn't close in middle or lower regions and spinal cord protrudes through the vertebrate)

effects of Illegal drugs (teratogens)

minimal evidence on fetal development (hard to test illegal drugs) -illegal drug use tends to be co-morbid with other risk factors -marijuana- some evidence of premature and low birth weight

four main processes in brain development

neurogenesis, neural migration, neural differentiation, and formation of neural connections.

Neural differentiation

occurs parallel to migration. The transformation of neural stem cells into differentiated types of neurons which take on a role and stay put.

kangaroo care

practices involving skin to skin contact between infant and parent for an extended period every day.

respiratory distress syndrome

preterm infants lungs do not produce enough surfactin (coats lining of lungs and helps absorb oxygen and dispose of carbon dioxide), leading to respiratory problems

effect of lack of calories as fetus

programmed to have slow metabolism to sustain low calorie diet when born (easier to gain weight when lots of food is available)

glial cells

provide support and nourishment to neurons and remove waste products.

affects of smoking on baby

raises carbon monoxide and lowers oxygen levels

cesarean section (rats, pros, cons)

rates increased dramatically (2008 approx 1/3 of all births) pretty unnecessary: more costly, increased risk of infections, avoid malpractice suits pros: avoid forceps/vacuum extraction, episiotomy (cutting)

angelogens

researchers are finding that many nutritional supplements can prevent and improve problems. Best shot at negating effects of teratogens

proximodistal

starts in center areas (internal organs) and proceeds to more distal areas

Overall birth info

stress hormones prepare baby for birth process and life outside womb. evidence that 'negative' and 'positive' experiences are context-dependent

done-response relationship

the amount and length of exposure to a teratogen. Important in figuring out the effects of exposure.

neurogenesis

the formation of new neurons within the brain. Usually complete by 5th month.

cleavage

the process of mitosis that turns the zygote into hundreds of cells for implantation

when does development of a fetus begin?

the second the sperm enters the ovum in the woman's fallopian tube to form a zygote. (conception)

how much of newborn behavior is already present in the final three months of fetal development?

they can recognize voices, see light, and recognize their native language.

synapses

tiny gaps across which an electrochemical signal can pass between two neurons allowing them to connect to each other.

low birth weight

under 5.5 pounds

what childbirth practices tell us about culture

value of women and children religious connection to children how a child should be raised the child's subsequent life experience

prenatal over nutrition

when mothers are overweight during pregnancy- overfeed baby and is predisposition to be overweight in childhood

vernix

white cheesy substance that covers the baby at 5 months to protect it from movement and amniotic fluid.

how the embryo is created

zygote reaches uterus and after a few days begins to divide continually via mitosis. Four days after fertilization, zygote have become a ball of cells with a hollow core, called a blastocyst. The cluster of cells inside the blastocyst develops into the embryo. The outer cells form supporting structures that sustain the embryo.