This document outlines the key stages of fetal development from conception to birth. It describes the processes of conception, fertilization and implantation that occur in the first 4 weeks. The major developmental changes that happen in each trimester are then outlined, including the formation of major organs in the first trimester, rapid growth and development in the second trimester, and further physical maturation in the third trimester as the fetus prepares for birth. Factors that can influence normal fetal growth rates are also briefly discussed.

1. FOETAL DEVELOPMENT
IN UTERO – OUTLINE
DR. MAHESWARI JAIKUMAR
maheswarijaikumar2103@gmail.com

2. PRIMER ON CONCEPTION
• Each month a group of eggs
(called oocytes) is recruited from
the ovary for ovulation (release
of the egg)
• The eggs develop in small fluid-
filled cysts called follicles

3. • Normally, one follicle in the
group is selected to complete
maturation
• This dominant follicle suppresses
all the other follicles in the
group, which stop growing and
degenerate

4. • The mature follicle opens and
releases the egg from the ovary
(ovulation)
• Ovulation generally occurs about
two weeks before a woman's
next menstrual period begins

5. After ovulation, the ruptured
follicle develops into a structure
called the corpus luteum, which
secretes progesterone and
estrogen

6. • The progesterone helps prepare
the endometrium (lining of the
uterus) for the embryo to
implant

7. • On average, fertilization occurs
about two weeks after your last
menstrual period
• When the sperm penetrates the
egg, changes occur in the protein
coating around it to prevent
other sperm from entering

8. FERTILIZATION

9. • At the moment of fertilization,
your baby's genetic make-up is
complete, including its gender
• If a Y sperm fertilizes the egg,
your baby will be a boy; if an X
sperm fertilizes the egg, your
baby will be a girl

10. • Human chorionic gonadotrophin
(hCG) is a hormone present in
your blood from the time of
conception
• It is produced by cells that form
the placenta and is the hormone
detected in a pregnancy test

11. • However, it usually takes three
to four weeks from the first day
of your last period for the hCG to
increase enough to be detected
by pregnancy tests

12. • Within 24 hours after
fertilization, the egg begins
dividing rapidly into many cells
• It remains in the fallopian tube
for about three days

13. • The fertilized egg (called a
blastocyte) continues to divide
as it passes slowly through the
fallopian tube to the uterus
where its next job is to attach to
the endometrium (a process
called implantation)

14. • Before this happens, the
blastocyte breaks out of its
protective covering
• When the blastocyte establishes
contact with the endometrium,
an exchange of hormones helps
the blastocyte attach

15. • Some women notice spotting (or
slight bleeding) for one or two
days around the time of
implantation
• The endometrium becomes
thicker and the cervix is sealed
by a plug of mucus

16. • Within three weeks, the
blastocyte cells ultimately form a
little ball, or an embryo, and the
baby's first nerve cells have
already formed

17. • The developing baby is called an
embryo from the moment of
conception to the eighth week of
pregnancy

18. • After the eighth week and until
the moment of birth, the
developing baby is called a fetus
• The development stages of
pregnancy are called trimesters,
or three-month periods, because
of the distinct changes that occur
in each stage

19. 8 WEEK FOETUS

20. • Foetal growth and maturation
from the 9th week foetal growth
is rapid
• Tissues grow by cell
proliferation, cell enlargement
and accretion of extracellular
material

21. • An adequate supply of nutrients
and oxygen from the placenta to
the foetus is crucial for growth
• As foetal is an indicator of foetal
health and wellbeing,
monitoring of growth is crucial

22. • This is done by visual
observation of the uterus for
size, fundal height measurement
and ultrasonograpy

23. 0-4 WEEKS
• Primitive streak appears
• Somebody systems laid down in
primitive form
• Primitive central nervous system
forms

25. • Heart develops and begins to
beat
• Covered with a layer of skin
• Limb buds form gender
determined

26. 4-8 WEEKS
•Rapid cell division
•More body systems laid
down in primitive form
•Blood is pumped around the
vessels

28. •Lower respiratory system begins
•Head and facial features develop
•Early movements
•Visible on ultrasound from
6weeks.

29. 8 WEEK FOETUS

30. 8-12 WEEKS
•Rapid weight gain
•Eyelids fuse
•External genitalia present but
gender not distinguishable

31. 9 WEEKS

32. •Finger nails develop
•Lanugo appears
•Some primitive reflexes
present

33. 12-16 WEEKS
•Rapid skeletal development –
visible on x-ray
•Meconium present in gut

34. •Nasal septum and palate
fuse
•Gender distinguishable

35. 16-20 WEEKS
•Constant weight gain
•Quickening mother feels
foetal movements

36. •Foetal heart sound heard
on auscultation
•Skin covered with lanugo
vermin caseosa is present

37. 20-24 WEEKS
• Legally viable and survival
may be expected is born
• Eyelids open

38. 17-20 WEEKS

39. •Most organs functioning
well
•Eyes complete
•Periods of sleep and
activity

40. •Ear apparatus developing
•Responds to sound
•Skin red and wrinkled

41. 24-28 WEEKS
• Legally visible and survival may
be expected if born
• Eyelids open
• Respiratory movements

42. 24 WEEKS

43. 28-32 WEEKS
• Begins to store fat and iron
• Tests descend into scrotum
• Lanugo disappears from face skin
and is less wrinkled

44. 32-36 WEEKS
•Testicle usually descend into
the scrotum
•One Lanugo tends to
disappear
• Head hair lengthens

45. 32 WEEKS

46. 36-40 WEEKS
•Both the testicle descends into
the scrotum
•Shape rounded
•Skull formed but soft and
palpable

47. 40 WEEKS

48. GROWTH OF THE FOETUS
• Normal foetal growth is
characterised by cellular
hyperplasia followed by
hyperplasia and hypertrophy and
lastly by hypertrophy alone

49. • The foetal growth increases
linearly until 37th week
• It is controlled by genetic factor
in the first half and by
environmental factors in the
second half of pregnancy

50. IMPORTANT
PHYSIOLOGICAL FACTORS
•RACE : European babies are
heavier than Indians

51. GENDER
• Male baby weighs greater
Female baby

52. PARENTAL HEIGHT AND
WEIGHT
• Tall and Heavier mother have
heavier babies

53. BIRTH ORDER
• Weight rises from first to
second pregnancy

54. SOCIOECONOMIC FACTORS
• Heavier babies in higher socio
economic class

55. THANK YOU