Physiological Changes of Pregnancy

Physiological Changes of Pregnancy

·              There are physiological biochemical and anatomical changes that occur during pregnancy. These changes may be systemic or local.

·              Most of the systemic changes return to pre pregnancy status 6 weeks after delivery.

·              These changes occur during pregnancy to maintain a healthy environment for the fetus with out compromising the mother’s health. And prepare for the process of delivery and care of the newborn.

·              Understanding of the normal changes helps to understand coincidental disease processes.

1. Gastro Intestinal Tract (GIT)

·              Nubribonal requirements including for vitamina and minerals are increased so usually mothr’s appetite increase

·              Pregnant women tend to rest more often conservig energy and there by enhancing fetal nutrition

Oarl cavity feels salivation

Gums- hypertkophic and hyperemic easily bleed (2⁰ to increased systemic estrogen)

Gastrointestinal mobility May be reduced due to increased progesterone (w/c decreased the hormone motline stimulate smooth msceles in GIt) hence gastric emptying is slowed and similarly in other part of GIT constipation (due to increased water absorption)

Stomach Production of gastrin increase increased arstric volume and decreases PH, mucous production increased PUD usually improve or disappear becuase of these changes during pregnancy,However during the pregnancy because of the enlarging uterus heart burn is common due to gastric refulex

Enlarging uterus slower emptying time, increase intragstric pressure increase acidty and increased gasric refulex

The anatomical postion of small and large intestine as well as appendix will shift because of the enlarging uterus

2. Galbladder 

Progestrone decresed motility → decreased emptiy time of bile →stasis →stone formation and infection.

3. Liver

No morphological changes but functional changes

Decreased plasma protein (albumen) an globline (synthesized by liver) increases serum alkaline phosphatese activity.

4. Urinary systems

-               Each kidney increase in length and weight

-               The renal pelvis and ureter dilate and lengthen

Thus there is an increase urinary stasis increase risk of infection and stone formation

·              Renal function

·              Chage occur due to increased maternal and placental hormones

·              (ACTH, ADH, cortisole, etc.) and increase in plamsma volume

·              Glomerular Filtration Rate increase by 50% (begins early and last up to term)

·              Renal  blood  flow  rate  increase  by  20-25%  (early  to midtrimester) after the end of 2^nd trimester remain constant.

·              Urine  volume  dose  not  increase  although  glomerular Filitration rate increase because of reabsorption.

·              Creatinine and BUN decrease because of increased clearance

·              rate

·              Glycosuria is not necessarily as normal

·              Protein uria changes little during pregnancy 

5. Bladder

Is displaced upward and anteriorly by enlarged uterus as a result it increases pressure leading to and urinary urgency and frequency

6. Hematological system:

·              Increase in blood volume – most striking change

·              The change occurs until term and the average increase in volume is 45-50%

·              The mechanism for increase the volume of blood is not well understood (aldestrone related factor during pregnancy may contribute to this effect) increase water and salt retention.

·              RBC increased by 33%

·              Iron need increases because of increase in red blood cell mass.This is why Iron suplimentation is necessary during pregnancy.

·              WBC total count usually increase

·              Platlates increase in production

·              Clotting factors - Several factors increase- F- I, F-VIII mainly

o     To lesses extent, F-VII, IX, X and XII

o     Decrease- F- XI, F-XIII

7. Cardiovascular System

Heart slightly shift in postion

Enlarging Uterus → diaphrym→ displace up ward → shift of apex beat Caradiac capcity increase by 70-80ml

Cardiac out put

i.                  increase a 49% during pregnancy reach may at 20-24 weeks of gestation the constant until term

ii.                  During early pregnancy SV increase by 25-30 % with length enig sesthtion HR increase (bttern increase by 15 b/min than non prgnancy) co=

Blood Presure

Systemic blood pressure declines slightly during pregnancy

There is little change in SBP but DBP decrease by 5-10 mmHg from 12-26 weeks, then incrase to non pregnant level by term.

Venous pressure

·              No change in the upper body

·              Increase in the lower extermities enlarged

·              Decrease venous return to the heart increases pressure and results in edema.

8. Plumunary system

Capillary dilatation occurs in the respiratory route (Nasopharynx, larynx, trachea, bronchi) → make breathing difficult through nose, elarged Uterus pushs the diaphragm and the lungs as well.

Summary of Pulmonary changes

Changes to volume

Tidal volume increase by 35-50%

Residual volume decreased by 20%

Expiratory reserve volume decrease by 20%

So increase Tidal volume and decrease Residual vloume → incrased alveolar ventilation by 65%.

Functional respiratory changes include

A slight incrase in respiratory rate

50% increase in minute ventilation

40% increase in minute tidal volume

Progressive increase in oxygen consumption (15-20% above non pregnant level by term)

9.  Changes in the Breast

Breast increases in size with enlargement of the nipple and increased vascularity and pigmentation of areola.

10. Change in Skin

Hyperpigmentaion over some part of the body

Face (forehead, cheek) - cholasma

Abdomen –subumbilical midline dark purplish pigmentation of linea alba- linea nigra Streach mainly

- Striea gravidarum

Enlarging abdomen → streach on collagen fibers of the skin and effect of ACTH

11. Change in Vagina and Uterus

Vagina – increase in capacity and length secondary to the hyperthrophy of the lining epithelium and muscle layer. Incresed glycogen content in the wall secondary to the effect of estrogen Increases vascularity and change the colour to purpleFold increases by term

·              Uterus – Upper part fundus and body change in to upper uterine segment

·              Lower part cervix and isthmus change in to lower uterine segment

·              Weight increases from 60gm to l kg at term, volume 10ml to 5 litres.