04-PRENATAL DEVELOPMENT AND BIRTH

Prenatal development

Pregnancy confirmation Can not be confirmed by blood or urine tests until the zygote implants in the uterus (about 10 days after conception).

Prenatal Development Germinal - 1 st 2 weeks Embryo – Week 3 to 8 (2 months) Fetus – Week 9 to birth

Germinal period First 2 weeks Conception Zygote Implantation

Embryo Week 3 – 8 (2 months) First - “Primitive streak” develops = neural tube = brain & spinal column 4 th. Week Head takes shape Early heart begins to pulsate 5 th. Week Arm & leg buds develop Webbed fingers and toes develop 8 th. Week 1 inch long Has all basic body parts and organs (except sex organs)

Embryo – 4 weeks

Embryo – 5 Weeks

Embryo – 7 weeks

Embryo – 8 Weeks

Fetus (9 weeks – Birth)

9 th. Week Male gene triggers development of male organs If not, female organs develop

Fourth, fifth, sixth months Heartbeat becomes stronger Digestive and excretory systems develop New neurons & synapses develop Up to one 500,000 brain cells per minute are created Age of viability Can possibly survive outside the mother (with intensive medical care) 22 weeks

Fetus (9 weeks - birth) Final three months Lungs begin to expand and contract (fetal respiration) Breathe using amniotic fluid as a substitute for air Fetus Grows and moves more Startles and kicks at a loud noise Becomes used to mother’s heartbeat and voice Responds if mother is fearful or anxious

Birth Labor 12 hrs. – first child Stages of labor 1 st. = Cervical dilation 2 nd. = Crowning About 31% of zygotes survive to be born

Birth in U.S.

Birth in Peru

Birthing chair - Egypt

Apgar Scale Color Heart Reflex Muscle Breathing (Respiration) Done twice – 1 & 5 minutes after birth to determine if immediate medical care is needed Score = 0,1,2 for each item Total of 7 or above is desired

Problems and Solutions

Teratogens: (Items increasing prenatal abnormalities) Types Substances (drugs, pollution) Conditions (Stress or malnutrition) Teratogens = Physical defects Cleft palate Thalidomide babies (deformed limbs)

Behavioral teratogens = Behavioral defects Hyperactivity Antisocial Learning-disabled

Teratogens: Critical factors Timing Some only cause damage during critical periods When organ or body part is most vulnerable Before pregnancy Avoid drugs (e.g. alcohol) Fetal alcohol syndrome Better diet Immunizations Problem – Half of births are unplanned Threshold effect Some are harmless until they “cross the threshold” and become harmful Alcohol, tobacco, and marijuana do more harm in combination This lowers the threshold for each Genes – May increase birth defects

Low birth weight Causes Born preterm Born small for gestational age (SGA) Maternal or fetal illness Drug use Every psychoactive drug Tobacco (Most prevalent cause) Malnutrition Consequences Infant death Thinking (cognitive) problems Seeing and hearing problems In adulthood - higher rates of: Obesity Heart disease Diabetes

Newborn reflexes Reflex = involuntary response to a stimulus Reflexes that aid survival Breathing – Maintains oxygen Shivering – Maintains temperature Sucking – Manages feeding Rooting – Searching for a nipple Reflexes that show the state of brain and body functions Babinski reflex – Toes fan upward when feet are stroked Stepping reflex Swimming reflex Palmer grasping reflex Moro reflex - Being startled

Sucking reflex

Grasping reflex

Stepping reflex