Physical and Physiological Changes in Pregnancy

Flashcards reviewing maternal anatomical, physiological, and biochemical adaptations during pregnancy based on lecture slides.

What is the primary source of progesterone during weeks 1 to 9 of pregnancy, and when does the placenta become the sole source?

The corpus luteum is the primary source during weeks 1 to 9, and the placenta becomes the sole source by week 12.

What are Goodell's sign and Chadwick's sign in relation to cervical changes during pregnancy?

Goodell's sign is the softening of the cervix, while Chadwick's sign is the congestion and bluish discoloration of the cervix and vagina due to increased vascularity.

By what percentage does cardiac output increase during normal pregnancy, and at what gestational age does it peak?

Cardiac output increases by 30-50% above non-pregnant levels and peaks at 28-32 weeks gestation.

How much blood is auto-transfused back into the systemic circulation with each uterine contraction during labor?

Each contraction auto-transfuses 300-500 mL of blood back into the circulation.

What causes physiological anemia of pregnancy, and what is the WHO threshold for diagnosing pathological anemia?

Physiological anemia is caused by a greater expansion of plasma volume (40-50%) relative to red cell mass expansion (25%). The WHO threshold for pathological anemia in pregnancy is Hb < 10.5 g/dL.

Why is pregnancy classified as a pro-coagulant state regarding clotting factors and fibrinolysis?

Fibrinogen increases by ~50% along with increases in Factors V, VII, VIII, IX, X, and XII, while Factor XI, Factor XIII, and Protein S decrease and fibrinolytic activity is depressed.

What arterial blood gas (ABG) findings characterize the normal compensated respiratory alkalosis of pregnancy?

A pH of 7.40-7.47, pCO2 of 3.7-4.2 kPa (28 mmHg), and compensatory HCO3 of 18-22 mmol/L.

How do tidal volume and functional residual capacity (FRC) change during pregnancy?

Tidal volume increases by approximately 40% (~700 mL), while functional residual capacity (FRC) decreases by approximately 20% (~1800 mL).

How does glomerular filtration rate (GFR) change in pregnancy, and what is the normal range for serum creatinine as a result?

GFR increases by ~50% (140-170 mL/min), which lowers normal serum creatinine to 35-75 µmol/L (a level > 90 µmol/L is pathological).

What two main mechanisms cause physiological hydronephrosis in up to 80% of pregnant women, and which side is more commonly affected?

Progesterone-induced smooth muscle relaxation of the ureters and mechanical compression by the dextrorotated uterus, affecting the right side more than the left.

Why is an elevated alkaline phosphatase (ALP) level normal in pregnancy, and which liver enzyme parameter confirms it is not cholestatic liver disease?

Elevated ALP (60-250 U/L) is normal due to placental isoenzyme production. A normal gamma-glutamyl transferase (GGT) level confirms the origin is placental rather than cholestatic.

How do serum ALT and AST levels change during a normal pregnancy?

Serum ALT (7-56 U/L) and AST (10-40 U/L) levels remain unchanged during normal pregnancy; any elevation is considered pathological.

What facial skin manifestation of pregnancy is shown in this image, characterized by hyperpigmentation across the cheeks and nose?

Chloasma (also known as the 'mask of pregnancy'), caused by increased production of melanocyte-stimulating hormone (MSH).

What vascular skin changes commonly appear during pregnancy as a result of elevated oestrogen levels?

Palmar erythema, telangiectasia, and spider nevi (telangiectasia with a central reddish spot).

Which hormones act as insulin counter-regulatory factors to create the pro-diabetogenic state of pregnancy?

Human placental lactogen (hPL), cortisol, oestrogen, progesterone, and prolactin.

According to IOM guidelines, what is the recommended total weight gain range during pregnancy for a woman with a normal pre-pregnancy BMI (18.5–24.9)?

11.5 to 16 kg.

Why does serum TSH decrease during the first trimester of pregnancy?

Human chorionic gonadotropin (hCG) cross-reacts with and stimulates the TSH receptor, causing transient suppression of TSH.

How do uterine weight and uterine blood flow change from pre-pregnancy to full term?

Uterine weight increases 20-fold (from 50 g to 1000 g) and blood flow increases 10-fold (from 50 mL/min to 500 mL/min).

Why are lower doses of spinal anaesthetics required in pregnant women?

Engorgement of the epidural venous plexus reduces epidural and subarachnoid space volume, leading to reduced CSF volume and greater spread of spinal anaesthetics.

What is the upper limit of normal for 24-hour urinary protein excretion in pregnancy, above which pre-eclampsia or renal disease is suspected?

Normal 24-hour urinary protein loss is < 300 mg/24 hours; excretion ≥ 300 mg/24 hours is pathological.