Lecture 03

FOETAL PERIOD-II

07th Month – Full Term

By:

A. Prof. Dr Farooq A. Khan

PMC

12th Dec. 2017

Nägele's rule

THE FOETAL PERIOD-II

Development during the fetal period is primarily concerned with rapid body growth, and differentiation of tissues, organs, and systems.

A notable change occurring during the fetal period is the relative slowdown in the growth of the head compared with the rest of the body.

Growth in length is particularly striking in the 3rd, 4th and 5th months.

While increase in weight is most striking during the last 2 months of gestation.

ERYTHROPOEISIS Erythropoiesis is the process of erythrocyte -

red blood cell - production.

All erythrocytes are derived from the division

and differentiation of a common stem cell

precursor.

The site of erythropoiesis varies with

developmental stage:

Embryo (2.5mm): Blood islands of yolk sac

Embryo (5-7mm): Liver and spleen

Fetus (20 weeks): Bone marrow takes over

Prepuberty: Medullary marrow of all bones

Postpuberty: Fatty yellow marrow replaces red marrow

from the peripheries of bones

Adult: Erythropoiesis only in ribs, sternum, vertebrae,

shoulder girdle, proximal femur and tibia

7th MONTH ( 25-28 weeks )

VERNIX: Covers the skin

HAIR: Lanugo and scalp hair well developed

EYES: Reopen at 26 weeks

NAILS: Become visible

SUBCUTANEOUS FAT:

Considerable amount is now present under the skin, smoothing out many of the wrinkles.

HAEMATOPOEISIS:

The fetal spleen is now an important site of hematopoiesis.

Erythropoiesis in the spleen ends by 28 weeks, and by this time bone marrow takes over this function.

25 week

7th MONTH ( 25-28 weeks ) cont’ d

PREMATURE BIRTH:

A foetus born towards the end of 7th month, often survives if given intensive care because its lungs are now capable of breathing air.

The lungs and pulmonary vasculature have developed sufficiently to provide adequate gas exchange.

In addition, the central nervous system has matured to the stage where it can direct rhythmic breathing movements and control body temperature.

28 week

8th MONTH

SUBCUTANEOUS FAT: is depositing (8%)

LANUGO LOSS:

Progressive loss of lanugo except for the hair on the eyebrows, eyelashes and scalp.

EYES: Pupillary light reflex +

SKIN: Pink and smooth

Fetuses 32 weeks and older usually survive if born prematurely. “Premature by date, not weight“.

9th MONTH

SKIN: Redness of skin fades and wrinkles smooth out

LANUGO: Further loss of lanugo

TESTES: Testes approaching scrotum

POSITION OF UMBILICUS:

Infraumbilical area relatively increases and so the umbilicus gradually becomes more centrally situated

By 36 weeks the circumferences of the head and abdomen are approximately equal.

After this, the circumference of the abdomen may be greater than that of the head.

In order to make this clear, the Health organization developed

these new labels for the last weeks of pregnancy:

Early term:

37 weeks, 0 days to 38 weeks, 6 days

Full term:

39 weeks, 0 days to 40 weeks, 6 days

Late term:

41 weeks, 0 days to 41 weeks, 6 days

Post term:

After 42 weeks, 0 days

FULL TERM (39 WEEK)

BODY: Plump

LANUGO: Disappeared

VERNIX: Present

UMBILICUS: Central

TESTIS: In the scrotum

OVARIES: Still above the pelvic brim

fULL TeRM (39 week) cONT’ d

By full term, most fetuses usually reach a

CRL: 360 mm and

WEIGHT: about 3400 gm.

WHITE FAT: 16 % (80% of which is underneath the skin, the other 20% around the organs)

In general, male fetuses are longer and weigh more at birth than females.

Although the head is smaller at full term in relation to the rest of the body than it was earlier in fetal life, it still is one of the largest regions of the fetus.

This is an important consideration related to its passage through the birth canal.

DIRECTIONS: Each of the following questions or incomplete statements below is followed

by five suggested answers or completions. Select the one that is correct in each case

MCQs

1. The CRL of embryo/foetus indicates

the:

A. Standing height

B. Greatest length of the embryo/foetus

C. Sitting height of the embryo/foetus

D. None of the above

E. All of the above

2. The length of pregnancy is:

A. 280 days or 40 weeks after the LNMP

B. 266 days or 38 weeks after the LNMP

C. 266 days or 40 weeks after the LNMP

D. None of the above

3. Ultrasonographic examination and measurement of

CRL is the method of choice in the:

A. 3rd trimester

B. 2nd trimester

C. 1st trimester

D. All of the above

Ans. B

4. In the 5th month of development, the head size of the foetus constitutes

approximately:

A. 1/3 of the CRL

B. 1/4 of the CRL

C. 1/3 of the CHL

D. 1/4 of the CHL

Ans. C

Ans. E

DIRECTIONS: Each of the following questions or incomplete statements below is followed

by five suggested answers or completions. Select the one that is correct in each case

MCQs

1. In the 4th month of development:

A. Eyes reopen

B. Vernix covers the skin

C. Spleen is actively forming the blood cells

D. Appearance of the foetus is truly human

E. All of the above

2. In the 5th month of development:

A. Mother feels the foetal mevements for the first time

B. Eyelids have widely opened

C. White fat is abundant under the skin

D. Testis are approaching the scrotum

E. None of the above

Ans. E

Ans. A

4. From 7th to 9th month of development:

A. Bone marrow is going to take over the function of hematopoiesis

B. Redness of the skin fades out

C. Progressive loss of lanugo takes place from 8th month onwards

D. Wrinkles of the skin smooth out

E. All of the above

3. In the 6th month of development:

A. Body of the foetus is plump

B. Skin of the foetus is smooth and rounded

C. Colour of foetal skin is pink and red

D. There is progressive loss of lanugo

E. If born prematurely, can survive with intensive treatment

Ans. E