Development in Fetus

1. Development in Fetus

2. Birth • Sudden, dramatic changes in hormone levels = starting of birth process • High levels of progesterone have maintained pregnancy – sharp drop in levels and estrogen – cause muscles of uterus to contract • Mother’s pituitary gland secretes oxytocin which stimulates the uterus to contract and open up birth canal = labour • Problems – mother’s pelvis is too small for baby to pass through, baby is in wrong position for birth • Sometimes – delivered by Cesarean section – remove baby through incision in mother’s abdomen and uterus

3. Labour • Dilation stage – uterine contractions, oxytocin levels = cervix opens • Amnion sac breaks – fluid is released through vagina • Lasts 2-20hrs • Expulsion stage – contractions of uterus become forceful, baby is pushed through cervix to birth canal • Takes .5-2 hrs

4. Labour (cont’d) • Placental Stage – placenta and umbilical cord are expelled from uterus • Within 10-15ms after baby is born • Expelled placenta = afterbirth

5. After birth • Baby’s umbilical cord is usually clamped, cut, tied • First time – baby must breath air, ingest food, eliminate wastes on its own • Accustom to light, sounds, cooler temperatures • Proportions of legs compared to rest of body changes with age