Third Trimester Discomforts: What to Expect and How to Actually Find Relief

The third trimester - weeks 27 through 40 - is the homestretch of pregnancy and the most physically demanding. The baby is growing rapidly (gaining approximately 200g per week in the final months), the uterus is at its largest, and many of the discomforts that make late pregnancy memorable converge simultaneously. Understanding why each discomfort is happening - and what evidence-based approaches actually relieve it - makes the final stretch significantly more manageable.

Back and Pelvic Pain

Lower back pain affects up to 70% of pregnant women and typically worsens in the third trimester as the baby's weight increases and the hormone relaxin loosens pelvic ligaments in preparation for labour. Pelvic girdle pain (formerly called symphysis pubis dysfunction) - pain around the front and sides of the pelvis - is a related condition affecting 20-30% of pregnant women.

Relief strategies:

• A pregnancy support belt provides external support to the heavy uterus, significantly reducing lower back strain
• Prenatal yoga specifically targeting the hip flexors and glutes (see our prenatal yoga guide) addresses the muscular imbalances driving much of the pain
• Swimming or water aerobics - buoyancy relieves gravitational load on the spine and pelvis
• Side-lying sleep with a pillow between the knees maintains pelvic alignment during the 7-8 hours of horizontal pressure each night
• Physiotherapy or osteopathy is genuinely effective for severe pelvic girdle pain

Heartburn and Acid Reflux

Up to 80% of women experience heartburn in the third trimester. The uterus pushes the stomach upward and the progesterone-relaxed lower oesophageal sphincter allows stomach acid to reflux into the oesophagus more easily. The burning sensation can range from mild to severe enough to disrupt sleep.

Relief strategies:

• Eat five to six small meals rather than three large ones - a full stomach presses upward more intensely
• Avoid lying down for 2-3 hours after eating
• Elevate the head of the bed 15-20cm (using a wedge pillow) to use gravity to keep acid in the stomach overnight
• Avoid known heartburn triggers: spicy foods, citrus, fatty or fried foods, carbonated drinks, chocolate, caffeine
• Calcium carbonate antacids (Gelusil, Digene) are safe in pregnancy; check with your doctor before using ranitidine or omeprazole

Swollen Feet and Ankles (Oedema)

Mild swelling of the feet, ankles, and legs affects 75% of pregnant women in the third trimester and worsens with heat and prolonged standing. It is caused by increased blood volume pressing fluid into the tissue spaces and the growing uterus compressing the vena cava, reducing venous return from the legs.

Relief strategies:

• Elevate the legs above heart level for 30-60 minutes daily - lying on the left side with legs propped is the ideal position (left lateral reduces vena cava compression)
• Walk regularly - the calf muscle pump actively returns venous blood upward
• Compression stockings significantly reduce oedema and are safe in pregnancy
• Reduce sodium intake (excess sodium promotes fluid retention)
• Stay well hydrated - counter-intuitively, dehydration promotes oedema as the body retains fluid to compensate
• Sudden or severe swelling of the face, hands, or one leg warrants immediate medical evaluation (pre-eclampsia risk)

Sleep Difficulties

By the third trimester, sleep becomes one of the most elusive comforts. Physical discomforts (back pain, heartburn, frequent urination from the baby pressing on the bladder), leg cramps, and anxiety about the impending birth all contribute. Research shows that third trimester sleep quality is a predictor of labour duration - poor sleep is associated with longer labours.

Relief strategies:

• A full-length pregnancy pillow (C-shaped or U-shaped) provides simultaneous support to the head, belly, and between the knees
• Left-lateral sleep position improves blood flow to the placenta and reduces vena cava compression
• Limit fluids in the two hours before bed to reduce nocturnal urination frequency
• The sleep hygiene practices for wind-down routine and bedroom environment are all applicable and beneficial in pregnancy

Shortness of Breath

The uterus pushes the diaphragm upward by approximately 4cm in the third trimester, reducing lung capacity. Shortness of breath with mild activity is common and normal. It typically improves in the final weeks before delivery as the baby's head engages into the pelvis ("lightening"), releasing pressure on the diaphragm.

Relief strategies:

• Sleep and rest in a propped-up position rather than flat
• Practice pranayama breathing techniques - particularly the ribcage-expanding breathing that maximises the reduced lung capacity
• Slow down and avoid rushing - shortness of breath worsens with exertion
• Sudden, severe, or worsening breathlessness warrants medical evaluation

Key Takeaway

Third trimester discomforts are physiologically predictable and largely manageable with targeted strategies. Back pain responds to support belts, targeted exercise, and positional adjustments. Heartburn responds to meal frequency and elevation. Oedema responds to elevation, compression, and hydration. Sleep responds to positional support and wind-down routines. None of these strategies eliminates the discomfort entirely, but each makes the final weeks significantly more comfortable - and allows you to arrive at labour better rested and physically prepared.