Back Pain in Pregnancy: Using Heat Safely

Back and pelvic pain affects a large share of pregnancies, usually from the second trimester onwards. It’s common, and it’s not something you have to simply put up with.

Why it happens

Three things stack up.

• Your bump shifts your centre of gravity forward, so the muscles along your spine work harder to keep you upright.
• Hormonal changes increase ligament laxity, so the pelvic joints move more than they’re used to.
• And the abdominal muscles stretch, which reduces the support they usually give your lower back.

Two patterns are common.

• Lumbar pain sits in the lower back, much like ordinary back pain.
• Pelvic girdle pain sits over the back of the pelvis, the pubic bone, or both, and is typically worse when standing on one leg, climbing stairs, rolling over in bed or getting out of a car. Pain further out on the side of the hip is usually something else: outer hip pain. Pain right at the tailbone: coccyx pain.

If pain or tingling runs down the back of one leg, see sciatica and heat.

Using heat safely

A heat pad on the lower back or the back of the pelvis is generally fine: lowest setting, cover on, 15 minutes. Keep it off your bump entirely, and off any caesarean scar that hasn’t fully healed (see heat after surgery).

Side-lying on your left with a pillow between your knees and one under the bump works well from the second trimester. A warm shower does much the same job if you’d rather not use a pad; on that difference, see moist heat vs dry heat.

The fuller safety picture, including why hot tubs and saunas are different from a heat pad, is in heat during pregnancy: what’s safe.

What helps day to day

• Keep your knees together when getting in and out of bed or a car. Roll onto your side first, then push up with your arms.
• Sit down to dress. Standing on one leg to put on trousers is a classic aggravator of pelvic pain.
• Take stairs one at a time, leading with the less painful leg.
• Shorter, more frequent walks rather than one long outing.
• Balance the load. Split shopping between two bags, or use a backpack.
• A pregnancy support belt helps many people with pelvic girdle pain. A physio can fit one properly.
• Swimming, if you’re comfortable in the water, takes load off the joints.

Sleeping

Side-lying with a pillow between the knees keeps the pelvis more level. A long body pillow or a folded blanket under the bump helps. Rolling over is often the painful moment: keep your knees together and move as one unit rather than twisting.

Heat before bed can settle things, but switch the pad off and unplug it before you sleep. See is it safe to sleep with a heating pad on?

See a women’s health physio

This is one of the clearest cases for getting proper help rather than managing alone. A physiotherapist who works in women’s health can tell lumbar from pelvic girdle pain, fit a support belt, give you exercises suited to your stage, and advise on positions for labour. Ask them exactly how they want the heat used.

Ask your doctor or midwife for a referral, or book directly.

Contact your doctor or midwife if…

• You have tummy pain, cramping or regular tightening. That’s not back pain and needs assessing.
• You have vaginal bleeding or fluid loss
• Back pain comes with fever, or burning when you pass urine, which can mean a kidney infection
• One calf is swollen, warm or tender. Get seen the same day.
• You have numbness around the groin, or trouble controlling your bladder or bowels. Go to A&E.
• You notice reduced movements from your baby

After the birth, two more: warm compresses for blocked ducts and mastitis, and new parent neck and shoulder pain.

Clinically reviewed by: Nigel Chua (Hand Occupational Therapist) & Louise Yow (Physiotherapist). This article is general information, not a diagnosis. electricheatpad.com sells electric heat pads.