Prenatal Development

Chapter 2 (second half)

Phase 1 of prenatal development

germinal (zygote) - conception to 2 weeks

rapid cell division and cell differentiation

from single cell to morula (3-4 days) to blastocysts (4-5 days)

ends with implantation of cells on the uterine wall

embryo

inner cell mass

placenta

Exchange point between mom and the developing organism

provides nutrition, oxygen, and allows for waste

outer layer

Phase 2 - Embryonic

3-8 weeks - organ development: specialized tissues (ectoderm, endoderm, and mesoderm)

critical period to have a stable foundation for these organs to develop

Folds in half and forms the neural tube (beginning of nervous system) (CNS and heart) (mesoderm)

sex differentiation begins - if contains the y chromosome it will take on a masculine role

Phase 3 - fetal (longest phase)

9 weeks to birth

ossification (bone development ) as the start

continued organ development and coordination (move-in different ways, wont be felt until 17 to 20 weeks)

fine-tuning: feature development and added protection (lanugo and vernix caseosa)

dramatic gains (weight, length, and brain)

Teratogens

environmental factor that causes damage or delay

types: drugs, illness, and environmental hazards

exposure is common

varied effects

timing - critical periods

dose, nature-nurture interaction (increased susceptibility), comorbidity, and immediate vs sleeper effects

RIsk factors

maternal nutrition - calories and nutritional content and critical periods

maternal distress - prolonged and severe and alters responsiveness of infant in post-natal environment

maternal age - over 35 at increased risks

paternal characteristics - context and age

prenatal care - barriers and interaction with culture

Prenatal Risk Conditons

gestational age - full term 38 weeks pre-term < 35 weeks

birth weight - pre-term or small for date, low <5.5 lbs at birth

consequences - can be offset

health screenings

APGARS - appearance, pulse, grimace, activity, respiration, and scoring

Interventions

sensitive parenting and kangaroo care (touch)

ectoderm

give way to form the skin, the nails, hair, and sensory organs. also the nervous tissue - CNS and PNS

endoderm

form the digestive system and the respiratory system

mesoderm

include the development of tissue that will become muscle, bone, connective tissue, and eventually the heart

languo

fine, downy like hair the coats the entire body of the fetus

purpose is to provide clutch or grip for Vernix caseosa

Vernix Caseosa

waxy type of covering that essentially protects delicate fetal skin