Which of the following are true statements regarding renal system changes in pregnancy? Select all that apply.

Urinary frequency in early pregnancyis due to uterine enlargementexerting pressure on the bladder, combined with hormonal effects of progesteroneand estrogen. Normal glomerular filtration rate (GFR) in non-pregnant adults is 90–120 mL/min, but in pregnancy, GFR actually increases by about 50% starting early in the first trimester. Plasma volume rises by 40–50%, and renal plasma flow increases by 50–80%, both enhancing urinary output. However, in the first trimester, the uterus remains a pelvic organ, directly compressing the bladder, leading to urinary frequency.

Rationale for correct answer

2.The enlarging uterus in the first trimester sits in the pelvis and presses on the bladder, reducing bladder capacity and causing urinary frequency. This mechanical pressure is the primary cause in early pregnancy before the uterus ascends into the abdominal cavity.

Rationale for incorrect answers

1.GFR does not decrease in pregnancy; instead, it increases significantly due to renal vasodilation and increased plasma volume. A decreased GFR would lower urine output, not increase urinary frequency.

3.Maternal blood volume does not reduce in pregnancy; it progressively increases by 40–50% to meet fetal and maternal needs. A reduced blood volume would impair renal perfusion, leading to oliguria, not urinary frequency.

4.Increased tubular reabsorption of fluid conserves body water and would reduce urine production. In pregnancy, although sodium and water retention occur, they do not directly cause urinary frequency in the first trimester.

Take home points

• First-trimester urinary frequency results from uterine pressure on the bladder.

• GFR increases in pregnancy, leading to greater renal clearance, not reduction.

• Maternal blood volume expands, not decreases, in pregnancy.

• Fluid reabsorption increases to maintain volume but does not cause frequency.

Heartburn in pregnancyis caused by progesterone-induced relaxationof the lower esophageal sphincterand increased intra-abdominal pressurefrom the enlarging uterus. Gastric acid reflux produces a burning retrosternal sensation. Normal gastric pH is 1.5–3.5, and when acid refluxes into the esophagus, mucosal irritation occurs. Risk factors include recumbency after meals, consumption of fatty or spicy foods, and delayed gastric emptying. Non-pharmacological interventions are first-line, with emphasis on dietary modifications and positional therapy to reduce acid exposure to the esophagus.

Rationale for correct answer

3.Consuming small, frequent meals reduces gastric volume, minimizing reflux into the esophagus. Smaller meals decrease gastric distension, lowering the pressure gradient across the lower esophageal sphincter and reducing the likelihood of acid regurgitation.

Rationale for incorrect answers

1.Increasing consumption of spicy foods exacerbates gastric acid secretion and directly irritates the esophageal mucosa, worsening heartburn symptoms. It increases mucosal sensitivity and reflux episodes rather than preventing them.

2.Eating large, infrequent meals distends the stomach, raising intragastric pressure and facilitating reflux through the weakened sphincter. This directly opposes recommended management.

4.Lying flat after eating increases the likelihood of acid reflux due to gravitational loss of barrier protection. The horizontal position facilitates acid movement from the stomach into the esophagus, worsening symptoms.

Take home points

• Heartburn in pregnancy results from progesterone-induced lower esophageal sphincter relaxation.

• Small, frequent meals are the best dietary modification to reduce reflux symptoms.

• Large meals, spicy foods, and lying flat exacerbate gastric reflux.

• Lifestyle changes precede pharmacologic interventions in management.