Fluid During Pregnancy

Fluid During Pregnancy: Fluid during pregnancy is a faint alkaline watery content of the amniotic sac in which embryo-fetus grow. It is primarily of foetal origin with maternal contribution V12 extraplacental membranes.

Physical Characteristics

(a) Early pregnancy: It is clear.

(b) Mid-pregnancy: More bile pigments make it yellow.

(c) Late-Pregnancy: Colourless as bilirubin becomes negligible, particulate matters= vernix caseosa and desquamated epidermis appear as white flocules.


At eight weeks of pregnancy, amniotic fluid is discovered.

10 Weeks30 ml.
20 Weeks300ml.
30 Weeks600 ml.
38 Weeks1000ml.
40 Weeks800 ml.
43 Weeks200 ml.


Early pregnancy-Same as Maternal Plasma with lowered proteins.

Late Pregnancy

Amniotic fluid is mixed with fetal urine and desquamation from fetal skin.


Composition of Amniotic Fluid During Pregnancy

(a) Water-98 to 99%

(b) Solid (Organic, Inorganic, (cells) 1-2%


(a) Protein including (a fetoprotein) 0.25gm%

(b) Uric acid 4 mg%

(c) Creatinine 1.8 mg.

(d) Glucose 20mg%

(e) Lipids

(f) Phospholipids

(g) Bilirubin (trace)

(h) Hormones (Prolactin)

(i) Vitamins

(j) Prostoglandins



(a) Electrolytes (Na, K,CI)

(b) pH = 7.2

(c) Specific Gravity = 1008



(a) Nucleated

(b) Anucleated derived from fetal skin, buccal & respiratory mucosa, bladder, umbilical cord, amnion.

(c) During mid pregnancy large eosinophillic nucleated cells

(d) During late pregnancy large anucleated cells. & nucleated cells from fetal skin are found.



It is colourless in the early stages of pregnancy, but near term it turns pale straw coloured because exfoliated lanugo and epidermal cells from the foetal skin are present. Due to the presence of vernix caseosa, it might appear turbid. Abnormal colour

(a) Meconium stained green-Present in fetal distress. Flake-filled and thick, this signals ongoing foetal distress.

(b) Golden Colour-Rh incompatibility.

(c) Greenish Yellow- Post Maturity.

(d) Dark Colored- Concealed accidental haemorrhage

(e) Dark brown (tobacco juice)-I.U.D (Intra Uterine Death)


Functions of Amniotic Fluid During Pregnancy

During Pregnancy

(a) Its main function is protective to the fetus.

(b) In pregnancy it acts as a shock absorber, protecting the fetus from possible extraneous injury.

(e) In pregnancy it maintains an even temperature.

(d) In pregnancy the fluid distends the amniotic sac and thereby allow for growth and free movement of the fetus and prevents adhesion between fetal parts and amniotic sac.

(e) It keeps fetus well by supplying mainly drinking water and helps in its growth.

(f) Serves Immunologic, (antibacterial) bio-chemical and hormonal functions.


During Labour

(a) Helps in dilatation of soft tissue of birth passage by fluid wedge of bag of membranes.

(b) Protects fetus and placenta from pressure contracting uterus.

(c) Washes the Vagina before birth of baby prevents infection of baby and uterine cavity.


Importance of studying liquor Amnii


  1. It helps in determination of adequate liquid volume.
  2. Foetal Maturity is determined by fetal lung surfactants (phospholipids) lecithin and sphingomyelin obtained in liquor amnii by Amniocentesis.
  3. Helps in determination of fetal distress as excess bilirubin in liquor amnii can detect affected fetal by rhesus (Rh) blood group Isoimmunization.
  4. Helps in determination of fetal malformation I.e. during 16-18 weeks cell culture of amniotic fluid obtained by amniocentesis can identify chromosomally defective babies e.g. Down’s syndrome.

Enzyme deficiency is cultured amniotic cells & amniotic fluid can identify metabolic error is fetus.

  1. Amniotic fluid excess alphafetoptotein (AFP) can identify fetus with open neural tube defects (Anencephaly).
  2. Rupture of the membranes with drainage of liquor is helpful method in induction of labour.

FAQs of Fluid During Pregnancy

Q.1. From where does placenta develop?

Ans. It develops from fetal chorionic tissue and maternal decidua during pregnancy.

Q.2. Where does it get implanted?

Ans. It is implanted on the uterine wall.

Q.3. With which structure is it connected to the fetus?

Ans. It is connected with fetus through umbilical cord in the amniotic cavity.

Q.4. What is the purpose of placenta?

Ans. It maintains pregnancy and carries vital fetal functions.

Q.5. At which week is placental site located by ultra sound?

Ans. By 8th week, placental site can be located by ultrasound.

Q.6. Name the types of Placental Villi

Ans. There are 2 types of placental villi:

(a) Anchoring Villi.

(b) Nutritive Villi.

Q.7. Give an example of acceptance of Immunological Acceptance of the fetal graft by the mother.

Ans. The fact that maternal and fetal tissue come in direct contact without rejection suggests immunological acceptance of the fetal graft by the mother.

Q.8. When is the interstitial implantation completed?

Ans. Interstitial implantation is completed on 11th day.

Q.9. When do the Stem Villi develop?

Ans. Stem villi develop on the 13th day.

Q.10. What is the purpose of the Stem Villi?

Ans. It connects the chorionic plate with the basal plate.

Q.11. From where do the Primary, Secondary Tertiary Villi develop?

Ans. These develop from Stem Villi.

Q.12. What is the system called which make connection with the intraembryonic vascula system?

Ans. It is called Arterio-Capillary-Venous System.

Q.13. Through what is Intraembryonic vacula system connected with Aeterio-capillary-venou system.

Ans. Body Stalk.

Q.14. At last which 2 parts form the discret Placenta?

Ans. These two, chorion frondosum and decidua basalis form the discrete placenta. get

Q.15. When does placenta formation start and completed?

Ans. It begins at 6th week and is completed by 12th week.

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