Prenatal Development

1. Prenatal Development Germination Stages of Prenatal Development Neonates

2. Germination Humans start off as a single cell organism: • Gametes: The male/female reproductive cells • Zygote: Formed an hour after the sperm enters the ovum when the two gametes fuse • Genes: Blueprints for creating a person • 25,000 of them • Composed of DNA molecules _______________________________________________________________ Deoxyribonucleic Acid: (DNA) • Located along 46 chromosomes which are organized in 23 pairs. • Each parent provides 23 chromosomes. • Possible combinations are limitless. • Nearly all of the cells of the body will contain the same 46 chromosomes as the zygote.

3. Prenatal Development Typically divided into Trimesters: • First: Conception to 3 months • Second: 3 to 6 months • Third: 6 to 9 months

4. Prenatal Development Conception • Occurs the moment a sperm cell fertilizes the ovum (egg cell), forming a single-celled zygote.

5. Prenatal Development Three Stages of Prenatal Development: • Germinal (2 weeks) • Begins with conception. • Takes place in one of the fallopian tubes. • Zygote travels to the uterus and attaches itself to the uterine wall. • Rapid cell division occurs • Once the zygote is successfully attached the germinal stage is over.

6. Prenatal Development • Embryonic (6 weeks) • Developing embryo forms all the major body systems, organs, and structures. • Lasts from the beginning of week 3 through week 8. • Begins when the zygote attaches itself to the uterine wall. • Ends when the first bone cells form. • 1 inch long and weighs 1/7 of an ounce. • Embryo already resembles a human being.

7. Prenatal Development • Fetal (38 weeks) • Lasts from week 9 (when first bone cells form) until birth. • Experiences rapid growth and further development of body structures, organs, and systems.

8. Prenatal Development • Teratogen (any agent that causes birth defects): • Drugs (prescription, nonprescription) • Alcohol, tobacco • Environmental pollutants • Infectious diseases • Nutritional deficiencies • Maternal stress • Advanced age of a parent • Severity of damage to the unborn depends on: • Dose • Time of exposure • Genetic susceptibility

9. Teratogens and Timing of Their Effects on Prenatal Development Zygote Embryonic period (wks) Fetal Period (wks) Central nervous system Heart Arms Most serious damage from teratogens in first 2-8 wks Eyes Legs Ears Teeth Palate Period of susceptibility to structural defects External genitalia Period of susceptibility to functional defects

11. Multiple Births Less than 3% of all cases result in twins • Any more is far less Two types of twins: • Monozygotic (Maternal twins): Identical • Dizygotic (Fraternal): Completely different individuals Mothers carrying multiple children run a higher risk of premature delivery and birth complications.

12. Neonates Labor: The Process of Birth Begins • Oxytocin: • Released by the mother’s pituitary gland. • When the concentration of oxytocin is high enough, mother’s uterus begins periodic contractions. • Braxton-Hicks Contractions: (After 4th month) • False labor • Contractions will eventually get strong enough to force the fetus down the birth canal until the baby enters the world.

13. Neonates:The Stages of Labor Most labors take 16-24 hours for firstborn children. • Duration of labor can vary depending on mother’s: • Age • Race • Ethnicity • Number of prior pregnancies

14. Neonates:The Stages of Labor Stage 1: (Longest stage) Labor • Uterine contractions every 8-10 minutes • Last 30 seconds • Toward the end contractions occur every 2 minutes • Last 2 minutes • As the contractions increase the cervix (separates uterus from the vagina) becomes wider • Eventually expanding to allow the baby’s head to pass through • Transition: Final part of the first stage • Fully opened cervix is usually around 10cm

15. Neonates:The Stages of Labor Stage 2: (Approx. 90 min) Delivery • Episiotomy: Incision made to increase the size of the vagina to help in stretching • Baby’s head emerges from the mother • Stage ends when the baby has completely left the mother • The placenta is still inside the mother at the end of this stage

16. Neonates:The Stages of Labor Stage 3: (Quickest stage) Afterbirth • Expelling of the umbilical cord and placenta (afterbirth) • Lasts just a few minutes • In most cases once a baby makes it outside they spontaneously cry, which helps them to clear their lungs of fluid • If they don’t the child may need to be stimulated or startled to make it cry • If it still does not: • Immediate life saving attention may be necessary

17. Neonates:Apgar Scale Rhythm: • Repetitive, cyclical pattern of behavior. • Important way that behavior can become integrated in the neuronal system and aide in the learning • Circadian Rhythm State: • Degree of awareness that an infant displays to both internal and external stimulation. • Alertness, fussing, crying, and different levels of sleep. • How much stimulation is necessary for a reaction

18. Neonates:Apgar Scale Apgar Scale Defined: A standard measurement system that looks for a variety of indications of good health in newborns. • Evaluates 5 basic qualities: • Appearance (color) • Pulse (heart rate) • Grimace (reflex irritability) • Activity(muscle tone) • Respiration (respiratory effort) Scoring: • From 0-2 on each of the five qualities • Score total ranges from 0-10 • Prognosis: • Score from 10 down to 8 means that the child is fine • Score from 7 down to 4 will most probably need help to start breathing • Score less than 4 means that the child needs immediate life-saving attention

19. The Apgar Scale