The back that aches by afternoon is still worth reading about.

Most of this desk is about a crash. This page is about the other thing, the ordinary thing, the back that is fine at breakfast and aching by three in the afternoon for no reason anyone will take seriously. It deserves careful reading on its own terms. It also happens to be the baseline against which a crash gets measured, and you cannot describe what is new if nobody ever helped you describe what was normal.

Why a pregnant back aches

Several things at once, none of them mysterious. Weight is added in front of the spine rather than around it, so the center of gravity moves forward and the curve of the low back deepens to keep you upright. The muscles along the spine work all day to hold that curve. The abdominal muscles, which normally share the job of bracing the trunk, are stretched as the belly grows and brace less. The hormones of pregnancy loosen the ligaments of the pelvis so it can open later, and looser ligaments mean the joints of the low back and pelvis move a little more than they used to and complain about it. Add the fact that every ordinary task, from a car seat to a grocery bag, is now done with a different lever arm, and afternoon soreness is not a surprise. It is arithmetic.

The neck nobody mentions

The back gets the attention, but the neck is doing its own second job. Side-lying sleep, which becomes the only comfortable option for many people by the third trimester, holds the neck at angles it did not choose for hours at a time. More of the day is spent looking down: at a phone, at a book, later at a baby. A neck that is stiff in the morning and eases by noon is common. A neck that is stiff and stays stiff, or that brings a headache with it, is worth mentioning to your OB, and if there has been any crash in the picture at all, worth its own page.

What ordinary looks like, and what does not

Ordinary is a dull ache across the low back or into one side of the pelvis that builds with standing or sitting and eases with a change of position, a walk, or lying down. Ordinary is worse at the end of the day and better in the morning. Ordinary responds to the boring things: moving more often, sitting with support, sleeping side-lying with a pillow between the knees, and not carrying the toddler on one hip for the whole trip through the store.

Not ordinary, and a call to your OB the same day: back pain with fever, with burning on urination, with bleeding or fluid, with contractions or a rhythm to it, with numbness or weakness in a leg, with any change in bladder or bowel control, or after a fall or a crash. Several of those are on this desk's emergency list as well. Your OB would rather take the call than have you decide it was probably nothing.

Sleep, and the pillow

The long body pillow is not a luxury. Side-lying with the top knee supported keeps the pelvis level and stops the low back twisting through the night; a second pillow under the belly takes the drag off the abdominal wall. Which side is a question for your OB, not for us. What we will say is that a neck pillow that actually fills the gap between the shoulder and the ear makes the morning neck less of an event, and that most people are using one that is too flat.

Sitting, standing, driving

Sit with the low back supported and the hips at least as high as the knees. Stand with the weight on both feet and change position often; the ache comes from holding one posture, not from any particular posture. In the car, the seat back slightly upright and the seat moved back, with the belt worn as the seat belt page describes. Get up every hour on a long drive. None of this is advice unique to pregnancy. Pregnancy just removes the margin that let you ignore it.

The question this desk will not answer

Whether chiropractic care, or any hands-on care, is safe for your pregnancy. It is the most common question we receive and it belongs to your OB or midwife before it belongs to any website. Ask them, get the answer in their words, and bring it to any appointment you make. A clinic that examines you can also tell you plainly what it will and will not do, and you are allowed to ask before anything is done.

When a crash enters the picture

Everything above is the baseline. The moment a crash is part of the story, the ordinary ache stops being ordinary, because now there are two timelines running through the same back and only one of them is expected. That is exactly what an early documented exam is for. Describe your baseline honestly, describe what changed since the crash, and let written findings do the separating. The sooner the exam, the cleaner that separation. The urgent page has the order of calls; the 72 hours page explains why the change arrives late. Missouri Injury Clinic's rooms: O'Fallon (636) 280-0990, Hazelwood (314) 627-1411, South County (314) 530-5480. Closed 12 to 2 daily.

The emergency line