Maternal changes during pregnancy

Trimester Structural Endocrine Systemic
First (1/52 – 12/52) Reduced lordosis

Posterior rotation of pelvis

Breast growth

Larger areolae

Uterus growth

Weight gain


Myometrium thickening

Blood vessel growth

Milk duct development

Ligament laxity

Progesterone (Corpus luteum)

Decidualisation of endometrium

Mature endometrium to secretory

Myomterial contraction inhibition

Breast tissue preparation

Relaxin (Corpus luteum & decidua)

Decidualisation of endometrium

Ligament laxity

Human chorionic gonadotropin (hCG)


Maintains corpus luteum, peaks 10/52

Increased cardiac output (50%)

Reduced peristalsis (progesterone)

Constipation (uterus growth, reduced peristalsis)

Polyuria (uterus growth)

Morning sickness.

Second (13/52 – 28/52) Expanding waistline

Mild anterior rotation of pelvis

Increased lordosis

Weight gain (back ache, see above)

Ligaments stretch to support the uterus (pelvic/abdominal ache)

Uterus to the height of naval

Visible bump at end of trimester.

HCG levels out

Progesterone and oestrogen gradually increase

Constipation (uterus growth)

Polyuria (uterus growth)

Bladder/kidney infection (uterus growth)


Gum bleeding (increased blood to mucous membranes)

Nasal congestion and nosebleeds (increased blood to mucous membranes)

Dizziness (vasodilation, lower blood pressure)

Third (29/52 – 40/52) Umbilicus protrudes

Weight gain

Back ache (hyperlordosis)

Ligament laxity (relaxin, weight)

Symphysis pubis dysfunction (SPD)

Progesterone and oestrogen at highest level Constipation (uterus growth)

Polyuria (uterus growth)

Kidney/bladder infection (uterus growth)

Braxton hicks (contractions)


Oedema (poor venous return)

Blood pressure increase – 140/90 (pre-eclampsia)

Heart rate increase (80-90 bpm)

Gestational Diabetes

Heartburn (cavity pressure)

Dyspnoea (cavity pressure)


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