MRCOG Part 1 Subject Guide

MRCOG Part 1: Physiology

~139 questionsHigh priority

Physiology is one of the highest-yield subjects in MRCOG Part 1, with approximately 139 questions. The majority focus on reproductive physiology and the hormonal control of the menstrual cycle, pregnancy and labour — making this the most clinically relevant basic science subject in the paper.

Topics Covered

Reproductive Physiology

  • Menstrual cycle and hormonal regulation (FSH, LH, oestrogen, progesterone)
  • Ovarian cycle — folliculogenesis, ovulation, corpus luteum
  • Hypothalamic-pituitary-ovarian axis and feedback mechanisms
  • Fertilisation, implantation and early pregnancy physiology
  • Placental physiology and fetoplacental unit
  • Physiology of labour and parturition — myometrial function, oxytocin
  • Lactation and prolactin physiology

Cardiovascular Physiology

  • Cardiac output, stroke volume, heart rate regulation
  • Physiological changes in pregnancy — increased blood volume, CO, decreased SVR
  • Blood pressure regulation and renin-angiotensin-aldosterone system
  • Haemostasis and coagulation — relevant to obstetric haemorrhage

Renal Physiology

  • GFR changes in pregnancy
  • Fluid and electrolyte balance
  • Acid-base physiology

Other Physiology Topics

  • Respiratory physiology in pregnancy — increased tidal volume, hyperventilation
  • Thyroid physiology — TBG changes, free vs total T3/T4 in pregnancy
  • Fetal physiology — circulation, haemoglobin, oxygen delivery
  • Neonatal transition and physiological changes at birth

Exam Tips for Physiology

1

The menstrual cycle and HPO axis are tested every sitting — know the hormone curves precisely.

2

Pregnancy physiological changes are extremely high-yield: know which parameters increase and by how much.

3

Fetal vs adult haemoglobin differences (oxygen affinity, P50) are a recurring question type.

4

Understand positive vs negative feedback — LH surge vs oestrogen negative feedback is a classic SBA trap.

5

Placental transfer mechanisms (simple diffusion, facilitated, active transport) are regularly tested.

Recommended Book

Essential Reproduction by Martin H. Johnson (8th Edition) — the best book for this subject.

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