1. Introduction:

After implantation of fertilized ovum the trophoblast secrets the following hormones within days:

1. Human chorionic gonadotrophin (hCG).
2. Human placental lactogen (hPL).
3. Sex hormones (Es. & Pr.)

2. HUMAN CHORIONIC GONADOTROPHIN (hCG):

• Is a glycoprotein hormone secreted by the syncytiotrophoblast.
• It can be detected within 10days after pregnancy by serum immune-assay (normal level in non pregnant woman= <3 IU/L).
• It peaks within 60-90 days of pregnancy & dropped to normal level within 7-10 days after delivery.
• 10% of hCG secreted in urine.

2.1. Functions of hCG:

1. Maintain corpus luteum (initial function).
2. Suppress maternal immunological reaction against the fetus.

3. HUMAN PLACENTAL LACTOGEN (hPL):

• After implantation, trophoblast differentiates into:
  • Syncytiotrophoblast (outer layer).
  • Cytotrophoblast (inner layer).
• hPL secreted from syncytiotrophoblast.
• It is β-glycoprotein pregnancy specific hormone.
• Half life= 20-30min.

3.1. Functions of hPL:

1. Breast growth during pregnancy.
2. Formation of colostrum.
3. Metabolic action (for energy).
4. Stimulate central secretion of insulin & inhibits it's effects at peripheral tissues, so it antagonize the cellular action of insulin & this may play role in the pathogenesis of gestational DM.
5. Retention of nitrogen which results in +ve nitrogen balance.
6. Maintain high concentration of progesterone during pregnancy.

4. PROLACTIN (PRL):

• Secreted from ant. lobe of pituitary gland.
• Released in amniotic fluid.
• Normal level in non pregnant woman <400 mU/L.

4.1. Functions of (PRL):

1. Regulates osmolarity of amniotic fluid.
2. It is involved in prostaglandins synthesis.
3. Stimulates surfactant.

5. ESTROGEN:

• Secreted initially from corpus luteum then from placenta after 12^th week which form it from certain precursors derived from fetal suprarenal cortex & liver.
• There are 3 types of estrogen:
  • Estrone.
  • Estriol (inactive form).
  • Estradiol (most active form).
• The ratio between these 3 forms is 3:2:1. During pregnancy it becomes 30:2:1.

5.1. Functions of estrogen:

1. Enhances RNA & protein synthesis.
2. Enhances growth of uterine muscles & increases size of breast & nipples.
3. Play role in water retention.
4. Stimulates synthesis of prolactin, but with progesterone it inhibits lactogenic effects of prolactin & hPL.

6. PROGESTERONE:

• Secreted from corpus luteum initially then from syncytiotrophoblast within 35days after fertilization.
• It's level reaches 150mg/ml at term.
• It is excreted in urine as metabolites called pregnandiol.

6.1. Functions of progesterone:

1. Reduces excitability of smooth muscles resulting in muscle relaxation:
   1. Uterine muscles.
   2. Urinary bladder → UTI.
   3. Esophageal sphincter → reflux of gastric juice.
2. Regulates storage of fatty acid in the body.
3. It is thermogenic hormone (increases body temp.).
4. It is precursors for fetal steroids.

7. MATERNAL BODY CHANGES DURING PREGNANCY

7.1. ENDOCRINE CHANGES:

• Pituitary gland:
  • Decrease level of FSH & LH.
  • Enlargement of ant. lobe due to increase in prolactin secreting cells.
  • Increase prolactin level up to 150mg/ml at term to ensure lactation.

• Thyroid gland:
  • Slightly enlarged (physiological goiter) due to deposition of colloid as a result of low iodine level.
  • Increase T₃ & T₄ level but TSH remains normal.
  • Increase thyroxin-binding protein level due to effect of estrogen to maintain normal activity of the gland.

• Adrenal gland:
  • Adrenal cortex hypertrophied.
  • Increase mineralocorticoids & glucocorticoids level.

• Parathyroid gland:
  • Increased in size & activity to regulate Ca⁺² metabolism.

7.2. GENITAL TRACT CHANGES:

• Ovaries:
  • Enlarged, edematous & increase in vascularity.
  • Corpus luteum degenerates after 10^th week.
  • Ovulation ceases due to pituitary inhibition by high level of Es. & Pr.

• Fallopian tubes:
  • Hypertrophied & become muscular. The epi. become flattened.

• Uterus:
  • Size: increases from 7.5x5x2.5 (in non pregnant) to 35x25x20 at term.
  • Wt.: increases from 50g (in non pregnant) to 100g at term.
  • Shape: globular (8^th week) – pyriform (16^th week).
  • Position: tilting to the Rt. (dextro-rotation) due to presence of sigmoid colon on Lt. side.
  • Consistency: become softer due to increase in vascularity & presence of amniotic fluid.
  • Contractility: from 1^st trimester uterus undergoes irregular contractions called (Braxton Hicks contractions) which are painless contractions.
  • Formation of lower uterine segment after 12^th week when the isthmus expanded. It measures 10cm in length at term.

• Cervix:
  • Hypertrophied & become soft, bluish in color.
  • Thick cervical secretions obstruct cervical canal by mucus plug.
  • Endocervical epi. proliferates forming cervical ectopy.

• Vagina:
  • Becomes soft, warm & moist.
  • Chadwick's sign is a bluish discoloration of the cervix, vagina, and labia caused by the hormone estrogen which results in venous congestion. It can be observed as early as 6-8wks after conception, and its presence is an early sign of pregnancy.

• Vulva:
  • Becomes soft & violet in color.
  • Edema & varicose veins may developed.

7.3. BREAST CHANGES:

• There is tingling & tenderness in early weeks.
• After 2^nd month, the breasts increase in size & become nodular due to hypertrophy of mammary alveoli. Veins become visible.
• Primary areola: it is well demarcated hyper-pigmented area around the nipple which becomes deeply pigmented during pregnancy.
• The nipples become larger, deeply pigmented & more erectile.
• Montgomery's tubercles: are hypertrophied sebaceous gland, appear as a non-pigmented elevations in the primary areola.
• Colostrum: is a thick yellowish fluid expressed from nipples after 3^rd month.
• Secondary areola: is an ill-demarcated pigmented area appears around the primary areola during 5^th month.

7.4. SKIN CHANGES:

• Pigmentation: due to increase production of melanocytes stimulating hormone (MSH)
  • Chloasma gravidarum (pregnancy mask): is a butterfly pigmentation appear on the cheeks & nose. It disappears few months after delivery.
  • Linea nigra: is a dark line extending from the umbilicus to symphysis pubis.

• Striae gravidarum:
  • Reddish slightly depressed streaks appear in the later months of pregnancy in the abdomen. Sometimes appear  on breasts & thighs.
  • It occurs due to mechanical stretching which result in rupture of elastic fibers in dermis & exposure of vascular subcutaneous tissues.
  • It becomes white in color after deliver but do not disappear & called (striae albicans).

• Vascular changes:
  • There is increase in blood flow & skin temp.

• Secretions:
  • There is increase in sweat & sebaceous glands activity.

7.5. CARDIOVASCULAR CHANGES:

• Heart:
  • Position: apex beat displaced upwards & to the Lt. (in 4^th intercostals space lateral to midclavicular line).
  • Rate: pulse increases by 10-15 beats/min.
  • Cardiac output: increases by increased stroke volume (30-50%).

• Blood vessels:
  • Arterial blood pressure decreases during 2^nd trimester lead to peripheral vasodilatation caused by Es. & Pr.
  • Blood pressure is affected by the posture of pregnant woman (highest in sitting position- lowest in lying position- intermediate in supine position).
  • Supine hypotensive syndrome: may develop in some pregnant in supine position due to compression on IVC by large pregnant uterus resulting in:
    • Decrease venous return.
    • Decrease cardiac output.
    • Low blood pressure.
  • Varicosities in the lower limbs & vulva may develop due to:
    • Back pressure from compressed IVC.
    • Relaxation of smooth muscles in the wall of veins due to effect of progesterone.

• Blood:
  • Plasma volume increased by 10^th week reaching maximum level at 32-34 weeks reaching 50% (1.2-1.5 Liter) due to increase stroke volume.
  • RBCs increase in mass.
  • Iron removed from site of storage & mobilized to be utilized by the pregnant woman (serum ferritin becomes low).
  • ESR becomes high (12-50 mm/hour).
  • WBCs & platelets become high.
  • Serum prolactin: low in 1^st trimester then increase.
  • β-globulin & fibrin become high. Hematocrit becomes low

7.6. RESPIRATORY CHANGES:

• Respiration:
  • Ventilation rate is increased.
  • Dysponea may occur due to:
    • Increase sensitivity of respiratory center to CO₂ due to high progesterone level.
    • Elevation of diaphragm by the pregnant uterus.

• Lung volumes:
  • Tidal volume increased.
  • Arterial Pco₂ decreased.

7.7. GASTROINTESTINAL CHANGES:

• Nausea (morning sickness) & vomiting (emesis gravidarum): occur in early months.
• Indigestion & flatulence: due to:
  • Decrease gastric acidity caused by regurgitation of alkaline secretion from intestine.
  • Decrease gastric motility.

• Hurt burn: occurs due to reflux of gastric content to the esophagus.
• Constipation: occurs due to:
  • Reduced motility in large intestine due to progesterone effect.
  • Increased water reabsorption from large intestine due to aldosterone effect.
  • Pressure on the pelvic colon by the pregnant uterus.
  • Sedentary life during pregnancy.

• Hemorrhoids: occur due to:
  • Mechanical pressure on the pelvic veins.
  • Laxity of the vein wall by progesterone.
  • Constipation.

7.8. URINARY CHANGES:

• Kidneys:
  • Renal blood flow & plasma flow increased.
  • GFR increased by (60%).
  • Increase excretion of urea, uric acid & nitrogenous products.
  • Progesterone causes loss of Na⁺ which compensated by rennin-angiotensin-aldosterone system.

• Ureters: dilation of ureters &  renal pelvis occurs due to:
  • Relaxation of the ureters due to progesterone effect which may cause UTI.
  • Pressure against the pelvic brim by the uterus.

• Bladder:
  • Frequency increased due to pressure of enlarged uterus & congestion of bladder mucosa.
  • Urinary stress incontinence may develop for the 1^st time & spontaneous relived.

7.9. IMMUNOLOGICAL CHANGES:

• Immune system suppressed.
• From 10^thwk IgG & IgM level decreased & peaks at 30^thwk. The reduction is due to hemodilutional effect.

7.10. Metabolic changes:

• Wt. gain (12.5 kg).
• Water retention.
• Nitrogen retention due to protein metabolism for fetal & maternal tissues formation.
• CHO metabolism: (pregnant woman is diabetogenic & glucosuric).
• Increased plasma lipid due to fat metabolism.
• Increased mineral demand (iron, Ca⁺², phosphate & magnesium).