1. Embryo to Fetus to Birth 1-3 Trimesters
Development
Embryo to Fetus to Birth
1-3 Trimesters

2. Neurula
Day 28
2-3.5 mm

4. Amniotic Sac Originally forms around the embryo
Eventually fills with liquid provided by the mother’s cells
Later, formed by the fetal kidneys
Circulates when the baby drinks the liquid and excretes it out

5. Amniotic Sac Some babies are born inside the amniotic sac
1 in 80,000 births

6. Umbilical cord Placenta
Umbilical cord: holds baby to the mother at the site of the placenta.
Placenta: on the surface of the uterus and is where diffusion of food, oxygen, carbon dioxide and waste takes place

7. The umbilical cord contains two arteries and a vein
The vein carries blood to the baby
The arteries carry blood away from the baby

8. 4 weeks
Brain is formed
Heart is beating
Eye, legs,arms begin
1/6 inch

9. 6 weeks
½ inch
Circulation begins
Toes and fingers forming

10. 8 Weeks Eyes, nose, lips, tongue, ears and teeth are forming
Gonad formation begins
Functioning heart
Now considered FETUS
1.2 inches

11. Sex of the baby can be determined Nails and earlobes develop
12 Weeks 2.5 – 3 inches and .5 – 1 oz.
Sex of the baby can be determined
Nails and earlobes develop
Eyes almost fully developed
All parts present, now major GROWTH and DEVELOPMENT

12. 2nd Trimester Placenta fully developed Fetus can hear mother
Week 13 to Week 27
Placenta fully developed
Fetus can hear mother
Vernix forms – creamy white substance that protects thin skin

13. 2nd Trimester Skin is reddish and forms lanugo (downy hair)
Reflexes: swallow, suckling, jumping

14. end of 2nd trimester: 15 inches long 2.5 pounds
Sleep – wakefulness cycles
Fat forms
lungs are beginning to exhale amniotic fluid
(practice for breathing)
circulatory system working

15. 3rd Trimester Fetus has sight and hearing Soft skeleton
Week 28 to Week 40
Fetus has sight and hearing
Soft skeleton
Laguno disappears – skin begins pigmentation
Circulatory and Respiratory systems mature

16. Mother’s antibodies pass to fetus
Digestive organs expel wastes- meconium
Baby moves downward towards birth canal

17. Parturition (Birth) Expel fetus from uterus = LABOR
Last few weeks of pregnancy, estrogen levels peak:
myometrium forms oxytocin receptors
Interrupts progesterone, allows small uterine contractions (false labor, Braxton Hicks)
Oxytocin production causes placenta to release prostaglandins = more powerful contractions

18. Positive Feedback Loop
Hypothalamus activated by increasing pressure levels on the cervix
Activates pituitary to release more OXYTOCIN…

19. Three Stages of Labor: DIALATION
True contractions dilates cervix 1 to 10 cm
Contractions
Increase from weak to vigorous
Regular
Upper uterus downwards to birth canal
Soften cervix: effaces
6-12 hours

20. Three Stages of Labor: EXPULSION
Delivery of infant out of vagina
Mother’s response is to push
Infant is facing downwards: vertex, if butt down: breech
Mucus is suctioned before full delivery – baby begins to breathe
Complications (dropping oxygen levels or heart rate in infant) overcome by forceps, vacuum or Cesarean section

21. Three Stages of Labor: PLACENTAL
Uterine contractions compresses blood vessels
Placenta detaches
Afterbirth = placenta, fetal membranes and umbilical cord
Need to remove all tissues – could cause excess bleeding