The document discusses fetal development from 6 weeks to 38 weeks of pregnancy. It describes the key physical changes that occur in the embryo and fetus each week. During the first trimester (6-12 weeks), major organs begin to form and external features develop. In the second trimester (13-28 weeks), the fetus grows rapidly and all systems continue to mature. By the third trimester (29-38 weeks), the fetus prepares for birth by gaining weight and fat and increasing lung and brain development.

1. FOETAL DEVELOPMENT
LINTU THOMAS
LECTURER,
GANGA INSTITUTE OF
HEALTH SCIENCES
COIMBATORE

4. INTRODUCTION

7. THE FOETAL PERIOD
 Beginning of the third month up to the termination of
pregnancy.

9. 6 week
 The formation of the lungs, jaw, nose, and palate begin now.
 The hand and feet buds have webbed structures that will become
the fingers and toes.
 The brain is continuing to form into its complex parts.
 A vaginal ultrasound could possibly detect an audible heartbeat at
this time.
 The embryo is about a ½ inch in length.

10. 8WEEKS
 13 mm in length (1/2inch).
 Lungs begin to form.
 Brain continue to develop.
 Arms & legs are lengthen, foot and hand
areas are distinguishable.
 Lymphatic system begins to develop.
 Development of external genitalia
started.

11. 9WEEK
 The embryo measures 18 mm (3/4 inch) in length.
 Fetal heart tone (the sound of the heart beat) can be heard using
Doppler.
 Nipples and hair follicles begin to form.
 Location of the elbows and toes are visible.
 Spontaneous limb movements may be detected by ultrasound.
 The vitelline duct normally closes

12. 10 -12 WEEK
 Embryo measures 30–80 mm (1.2–3.2 inches) in length.
 Ventral and dorsal pancreatic buds fuse during the 8th week
 Intestines rotate.
 Facial features continue to develop.
 The eyelids are more developed.
 The external features of the ear begin to take their final shape.
 The head comprises nearly half of the fetus' size.
 The face is well formed

13. 10-12 WEEK
 Tooth buds, which will form the baby teeth, appear.
 The fetus can make a fist with its fingers.
 Genitals appear well differentiated.
 Red blood cells are produced in the liver.

14. 9-12 WEEK
.
 End of 12th week crown rump length almost doubles.
 During 9th week ,the face is broad, eyes get widely separated,
ears are low set and eye lids get fused.
 By 11th week intestine return to abdomen.

15. 13 -16 WEEK
 14th week –lower limb lengthen and limb movement
co-ordinated.
 Active ossification in fetal skull.
 Slow eye movement.
 End of 16th week eye placed anteriorly and ears get close to
definitive position.

17. 13-16 WEEK
 The fetus reaches a length of about 15 cm (6 inches).
 A fine hair called lanugo develops on the head.
 The fetus makes active movements.
 Sucking motions are made with the mouth.
 Meconium is made in the intestinal tract.
 The liver and pancreas produce fluid secretions.
 From week 13, sex prediction by obstetric ultrasonography
is almost 100% accurate.

18. 17 -20 WEEK
 Limbs reached their final relative proportion & mother feels
quickening.
 By 20th week eye brows & hair
Appears & also lanugo developed.
 By 18th week uterus is formed & canalization of vagina has
begun.
 By 20th week testis begin to descend
& reach posterior abdominal wall.
 Nails appeared in the finger toe.
 Heart beat can be heard using stethoscope.

19. 23RD WEEK
 The fetus reaches a length of 28 cm (11.2 inches).
 The fetus weighs about 925g.
 Eyebrows and eyelashes are well formed.
 All the of eye components are developed.
 The fetus has a hand and startle reflex.
 Footprints and fingerprints continue forming.
 Alveoli (air sacs) are forming in lungs.

20. UPTO 25 WEEK
 Weight gaining continuous.
 21th week rapid eye movement begin.
 By 24th week type 2 pneumocytes begin to secret surfactant
that maintains patency of developing alveoli of lungs.

21. 27 WEEK
 The fetus reaches a length of 38 cm (15 inches).
 The fetus weighs about 1.2 kg (2 lb 11 oz).
 The brain develops rapidly.
 The nervous system develops enough to control some body
functions.
 The eyelids open and close.
 The respiratory system, while immature, has developed to
the point where gas exchange is possible.

22. 26-29 WEEK
 Lungs &pulmonary vasculature develops.
 Central nervous system matures &control temperature.
 Eye lid opens in 26th week.
 Toe nails visible.
 The cochleae are now developed,
Though the myelin sheaths in neural
Portion of the auditory system will
Continue to develop until 18 months after birth.

23. 31 WEEK
 The fetus reaches a length of about 38–43 cm (15–17 inches).
 The fetus weighs about 1.5 kg (3 lb 0 oz).
 The amount of body fat rapidly increases.
 Rhythmic breathing movements occur, but lungs are not fully
mature.
 Thalamic brain connections, which mediate sensory input, form.
 Bones are fully developed, but are still soft and pliable.
 The fetus begins storing a lot of iron, calcium and phosphorus.

24. 30-34 WEEK
 At 30th week pupillary light reflex can be elicited.
 Skin pink & smooth.
 Limb appears chubby

25. 35 week
 The fetus reaches a length of about 40–48 cm (16–19 inches).
 The fetus weighs about 2.5 to 3 kg .
 Lanugo begins to disappear.
 Body fat increases.
 Fingernails reach the end of the fingertips.
 A baby born at 36 weeks has a high chance of survival, but may
require medical interventions.

26. 35-38 WEEK
 Spontaneous orientation to light.
 By 36 week head &abdominal circumference are equal.
 Chest is prominent & breast protrude in both sexes.
 Testes are usually in the scrotum in full term male baby.

27. RESEARCH