back pain.
last revised · reviewed 2026-07-05
Lower back pain affects up to two thirds of pregnant women, usually from mid-pregnancy onwards, as the growing bump shifts your centre of gravity and the hormone relaxin loosens supporting ligaments. Movement, posture care, and support usually manage it well.
what it feels like
A dull ache or stiffness across the lower back, often worse at the end of the day, after standing or sitting for long stretches, or when rolling over at night. It may spread into the buttocks and thighs, and can flare with lifting or bending.
why it happens
The bump moves your centre of gravity forwards, so the lower back arches more and its muscles work overtime. Meanwhile relaxin loosens the ligaments of the spine and pelvis in preparation for birth, giving the back less passive support exactly when it needs more. Weight gain and abdominal muscles stretching add to the load.
what helps
- Keep moving — regular walking, swimming, or aquanatal classes beat prolonged rest
- Mind your posture: stand tall, avoid locking your knees, and don't stand on one hip
- Bend at the knees to lift, keeping the load close; avoid heavy lifting where possible
- Sleep on your side with a pillow between your knees and one under the bump
- A warm bath or covered heat pack relaxes aching muscles
- A maternity support belt can help in later pregnancy, especially on long days upright
- Ask about pregnancy physiotherapy if pain limits daily life — it works, and you don't need to soldier on
when to call your midwife or doctor
- Back pain with rhythmic tightening, pelvic pressure, or cramping before 37 weeks — could be preterm labour; call your midwife or maternity unit
- Pain with fever, or burning when passing urine — possible kidney infection
- Numbness in the saddle area, leg weakness, or loss of bladder or bowel control — emergency, seek help immediately
- Severe pain that doesn't ease with rest or paracetamol — call your midwife or doctor
This page is general information, not a diagnosis. When in doubt, call — no midwife has ever minded a careful question.
common questions
When does back pain usually start in pregnancy?
Most women first notice it between weeks 20 and 28, once the bump is heavy enough to change posture — though relaxin means it can start earlier. It tends to build gradually through the third trimester without proper posture care and movement.
Can I use heat or a TENS machine for pregnancy back pain?
A warm (not scalding) bath or a covered heat pack on the back is fine and effective. Maternity TENS machines are considered safe for back pain from the second trimester and are widely used in labour — check with your midwife about using one earlier or for other areas.
Is back pain ever a sign of labour?
It can be — labour sometimes announces itself as rhythmic lower-back pain that comes in waves, with or without tummy tightening. Constant ache is usually muscular; pain that comes and goes in a pattern, especially before 37 weeks, warrants a call to your midwife or maternity unit.
read it in context
Back pain tends to show up around these weeks of pregnancy:
related symptoms
- Mucus plug
The mucus plug is a thick seal of jelly-like mucus that blocks the cervix throughout pregnancy, and losing it — the 'show' — means the cervix is beginning to soften and open.
- Pelvic girdle pain
Pelvic girdle pain (PGP) is pain around the pelvic joints — the pubic bone at the front, or the sacroiliac joints at the back — affecting around 1 in 5 pregnant women.
- Carpal tunnel syndrome
Carpal tunnel syndrome — tingling, numbness, and aching in the fingers and hand — affects up to a third of pregnant women, usually in the third trimester.
know what's normal, week by week
elara tracks your symptoms alongside your weeks.
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