Pregnancy Physiology & Nutritional Needs: NCLEX Guide

Pregnancy physiology and nutritional needs cheat sheet for nursing students studying maternity and NCLEX prep

Table of Contents

During pregnancy, a woman’s body undergoes massive physiological changes to support fetal development. For the NCLEX, you must be able to differentiate between normal expected findings (like mild respiratory alkalosis or dependent edema) and abnormal findings that require immediate intervention.

Use our comprehensive cheat sheet below to review maternal body system changes, essential hormones, and strict nutritional requirements during pregnancy!

1. Physiological Body System Changes

Almost every body system is impacted by the growing uterus and the dramatic shift in hormones.

Body System Expected Physiological Changes
Respiratory
  • Increased oxygen needs (lungs oxygenating more blood)
  • Uterus size increases, causing shortness of breath (SOB) in late trimester
  • Increased tidal volume and respiratory rate
  • May experience mild respiratory alkalosis/acidosis shifts
Circulatory
  • Increased cardiac output and blood volume
  • Uterus compresses pelvic blood vessels (leads to varicose veins)
Hematological
  • Increased fibrinogen, WBCs, and overall blood volume
  • Safety Alert: Causes a hypercoagulable state (Increased risk for blood clots/DVT)
Musculoskeletal
  • Relaxin hormone: Makes ligaments & joints more flexible (Risk for injury!)
  • Lordosis: Center of gravity shifts forward causing an arch in the lower back
  • Frequent lower back pain & calf cramping
Skin
  • Striae: Stretch marks
  • Linea nigra: Dark line running down the center of the belly
  • Melasma: Brown patches on the cheeks, forehead, or nose (“mask of pregnancy”)
Gastrointestinal
  • Increased progesterone causes GI muscles to relax
  • Leads to heartburn and constipation (decreased motility)
  • Nausea/vomiting driven by increased HCG levels
Renal / Urinary
  • Glomerular Filtration Rate (GFR) increases up to 50% from extra plasma volume
  • Smooth muscle of bladder relaxes (Increased risk of UTIs)
  • Increased protein excretion in urine
  • Uterus presses on bladder causing frequency and urgency

2. Key Pregnancy Hormones

Progesterone and estrogen rise dramatically during pregnancy, supported by hormones produced directly by the placenta.

Hormone Function / Effect on the Body
Progesterone Thickens the uterine lining, aids in milk duct development, and inhibits oxytocin to prevent premature labor.
Estrogen Aids in fetal development and helps maintain the uterine lining.
HCG
(Produced by Placenta)		 Stimulates the corpus luteum to produce estrogen & progesterone to maintain the pregnancy.
hPL
(Produced by Placenta)		 Gives nutrition to the fetus and regulates maternal metabolism.
Prolactin Prepares breasts for milk production.
Oxytocin Stimulates uterine contractions during the start of active labor.

3. Nutritional Needs & Weight Gain

Maternal nutrition directly impacts fetal growth, birth weight, and the prevention of congenital anomalies.

Folic Acid Rule: Highly recommended when trying to conceive (2-3 months prior) and until 12 weeks pregnant to help prevent neural tube defects.
Category Guidelines & Requirements
Calories & Weight Gain
  • 1st Trimester: Gain 2–4 lbs total.
  • 2nd & 3rd Trimester: Gain 1 lb per week.
  • Need an extra 300–500 calories/day. Do NOT restrict calories!
Protein
  • Minimum 60g/day for the entire pregnancy.
  • Include complete proteins (meat, poultry, eggs, dairy).
  • Note for Vegans/Vegetarians: B12 is found in animal protein. Decreased intake requires a B12 supplement!
Vitamins & Caffeine
  • Vitamin D: Essential for calcium absorption.
  • Vitamin A: Too much causes birth defects; too little causes poor night vision.
  • Caffeine: Limit to <200 mg/day (too much decreases blood supply and inhibits fetal growth).
Recognizing Pica: Pica is a craving for unusual, non-food related items like salt, ice, clay, or dirt. This is usually triggered by an underlying vitamin deficiency (like iron) and increases the risk of preterm delivery and low birth weight.

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