1. FETAL CIRCULATION

2. CHARACTERISTICS OF FETAL CIRCULATION
Placenta is the source of oxygen for the fetus.
Lungs do not exchange gas.
Right atrium of fetal heart is the chamber with the highest oxygen concentration.

3. STRUCTURES OF FETAL CIRCULATION
Umbilical vein.
Ductus venosus (from vein to a vein).
Foramen ovale (oval opening).
Ductus arteriosus (from an artery to an artery).
Two umbilical arteries.
Hypogastric arteries. ]

10. CHANGES AT BIRTH Closure of the foramen ovale.
Closure of ductus arteriosus.
Closure of umbilical vein.
Closure of umbilical arteries.

12. FETAL DEVELOPMENT

13. CONCEPTION - 4 WEEKS Rapid growth. Formation of embryonic plate.
Development and beating of the heart.
Formation of limb buds.

14. 4 – 8 WEEKS. Rapid cell division. Head and face develops.
All major organs are present in primitive form.
External genitalia is present but not distinguishable .
Early fetal movement present in USG

15. 8-12 WEEKS
Eye lids fused .
Kidney begins to function, urine formation occur by 10 weeks.
Fetal circulation well established.
Sucking and swallowing established.
Sex apparent .
Moves freely.
some primitive reflex present.

16. 12-16 weeks Rapid development of skeleton visible on x-ray.
Presence of meconium in the gut .
Appearance of lanugo hair.
Nasal septum and palate fuse.

17. 16-20 weeks Quickening . Fetal heart sound audible on auscultation.
Appearance of vernix caseosa .
Finger nails seen.
Renewal of shed skin cells.

18. 20-24 weeks Most organ capable of independent functioning.
Alternate period of sleep and activity.
Fetus responds to sound - startle response.
Skin brick red and wrinkled.

19. 24-28 weeks Survival expected if born. Eye lids reopen.
Respiratory movements present.

20. 28-32 weeks Begins to store fat and iron.
Testes descend into the scrotum.
Lanuguo begin to disappear from the face.
Skin becomes paler, and wrinkles to diminish .

21. 32-36 weeks Increased fat deposition. Lanugo disappear from the body.
Scalp hair lengthen .
Nails reach tip of fingers.
Ear cartilage soft.
Plantar creases visible .

22. 36-40 weeks
Term reach ,
skull firm , labour due.