Maternal Adaptations for Pregnancy

Hormones & Endocrine

100

This placental hormone rises rapidly after implantation, peaks at approximately 8–10 weeks, and maintains the corpus luteum early in pregnancy.

What is human chorionic gonadotrophin (hCG)?

200

This hormone helps maintain pregnancy by relaxing smooth muscle and suppressing uterine contractions, but also contributes to constipation and reflux.

What is progesterone?

300

This placental hormone promotes maternal insulin resistance and lipolysis, allowing the mother to use more fatty acids while sparing glucose for the foetus.

What is human placental lactogen (hPL), or human chorionic somatomammotropin?

400

Pregnancy activates this hormonal system despite the mother being relatively vasodilated. Its end result is increased sodium and water retention.

What is the RAAS system?

500

Name TWO major endocrine/hormonal adaptations of pregnancy and give one major effect of each.

Any TWO of:

• hCG ↑ → maintains corpus luteum early in pregnancy.
• Oestrogen ↑ → uterine/breast growth + increased vascularity.
• Progesterone ↑ → maintains pregnancy and relaxes smooth muscle.
• hPL ↑ → insulin resistance/lipolysis → glucose spared for foetus.
• Prolactin ↑ → prepares breast for lactation.
• FSH/LH ↓ → ovulation suppressed.
• CRH/ACTH/cortisol ↑ → metabolic adaptation + foetal maturation.
• RAAS/aldosterone ↑ → Na⁺ and water retention.
• Thyroid activity ↑ → accommodates increased metabolic demand.
• Active vitamin D/intestinal Ca²⁺ absorption ↑ → supplies foetal skeletal mineralisation.
• Relaxin ↑ → pelvic-ligament laxity + cervical softening. 

Body Systems & Anatomy

100

During pregnancy, both renal plasma flow and this measure of renal filtration increase by approximately 40–50%.

What is glomerular filtration rate (GFR)?

(Consequences:

• ↓ serum creatinine
• possible mild glycosuria
• increased urine production. )

 

200

Maternal plasma volume increases by approximately this percentage during pregnancy.

What is 40–50%?

300

In any body systems, state one physiological adaptation AND one clinical consequence of that adaptation.

Any of:

• Cardiovascular
  • ↑ Plasma volume by ~40–50%
  • ↑ Heart rate, stroke volume and cardiac output
  • ↓ Systemic vascular resistance → BP may fall mid-pregnancy
  • ↑ Blood flow to uterus/placenta, kidneys, skin and breasts

• Haematological
  • Plasma volume increases more than RBC mass → physiological dilutional anaemia
  • ↑ Clotting tendency / hypercoagulability
  • → ↑ risk of venous thromboembolism (VTE)

• Renal / urinary
  • ↑ Renal plasma flow and GFR by ~40–50%
  • ↑ Na⁺ and water retention via RAAS/aldosterone
  • Ureters dilate + uterus compresses bladder
  • → urinary frequency/urgency, ↓ serum creatinine, ↑ UTI risk

• Respiratory
  • Progesterone ↑ sensitivity of respiratory centre to CO₂
  • ↑ Tidal volume and minute ventilation; respiratory rate changes little
  • ↓ PaCO₂ → mild compensated respiratory alkalosis
  • Diaphragm rises → mild dyspnoea may occur

• Gastrointestinal
  • Progesterone ↓ GI motility
  • ↓ Lower oesophageal sphincter tone
  • Growing uterus displaces GI organs upwards
  • → constipation, reflux/heartburn, bloating and haemorrhoids

• Immune
  • Maternal immune responses are dynamically regulated
  • Allows tolerance of the semi-allogeneic foetus while maintaining antimicrobial defence
  • Inflammatory patterns change throughout pregnancy

400

List FOUR common anatomical or visible changes of pregnancy.

Any FOUR of:

• Enlarged uterus
• Increased lumbar lordosis
• Pelvic ligament/pubis symphysis laxity
• Chadwick sign
• Breast enlargement
• Darkening/enlargement of areolae
• Linea nigra
• Striae gravidarum
• Spider angiomas
• Increased pigmentation
• Diastasis recti
• Rib flaring/increased thoracic width
• Hair changes. 

500

A heavily pregnant patient becomes dizzy and hypotensive while lying flat. Explain the mechanism and the simplest positional treatment.

What is supine hypotensive syndrome due to uterine compression of the inferior vena cava?

Pregnancy and Lactation

100

This anterior pituitary hormone increases markedly during pregnancy and is principally responsible for milk synthesis after delivery.

What is prolactin?

200

These two hormones stimulate breast development during pregnancy but simultaneously inhibit copious milk secretion until after delivery.

What are oestrogen and progesterone? 

( Oestrogen → ductal development

Progesterone → lobulo-alveolar development

High levels inhibit full prolactin-mediated milk secretion before birth. )

300

Name the hormone responsible for milk production and the hormone responsible for milk ejection/let-down.

Prolactin = milk production
Oxytocin = milk ejection 

(Memory trick: PROlactin → PROduction, Oxytocin → OUT)

400

Explain why copious milk production begins shortly after the placenta is delivered even though prolactin was already high during pregnancy.

During pregnancy: ↑ oestrogen + ↑ progesterone
→ inhibit prolactin's full milk-secreting effect.

After placental delivery: ↓↓ oestrogen + progesterone
→ removes inhibition
→ prolactin can act effectively on mammary alveolar cells
→ lactogenesis begins. 

500

A baby suckles at the breast. Describe the complete hormonal pathway leading to continued milk production, milk ejection and temporary suppression of fertility.

1. Suckling → 2. Hypothalamus → 3. Anterior pituitary 

4. Anterior pituitary → Prolactin → mammary alveolar epithelial cells produce milk (helps prepare milk for subsequent feeds)

5. Posterior pituitary → Oxytocin → myoepithelial cells surrounding alveoli contract → milk ejection / let-down.

5. Suppression of fertility (Reproductive axis):

Suckling/prolactin
→ ↓ hypothalamic GnRH
→ ↓ LH + FSH
→ ↓ ovulation
→ lactational amenorrhoea.

However, fertility can return before the first menstrual period, so breastfeeding does not automatically guarantee contraception.