The answer to this question is that back pain can be a sign of labor, but it isn’t always. Read on to learn about back pain during pregnancy and when it might mean that your baby is on their way.
Back Pain as a Sign of Labor
Back pain alone is not usually a sure sign of labor, but accompanied by other signs—such as, vaginal discharge that is brown or bloody, rhythmic cramps, and your water breaking—it can be an indicator that labor is here. Back pain that signals labor’s onset is usually persistent. It might come and go, but it often does so with a rhythm. It might be reminiscent of back pain that you have experienced before your menstrual period or cramping pains that are associated with the need to poop. This type of back pain is most likely to be in your lower back, or perhaps across your sacrum and hips. 
Non-Labor Back Pain
If you are already pregnant, you probably know that back pain can be really common during pregnancy. Here, we will discuss the other types of back pain that can be uncomfortable, but likely do not signal baby’s imminent arrival.
Upper back and shoulder pain are both common during pregnancy. Loosening of ligaments and connective tissue—a natural outcome of the body’s release of the hormone relaxin—can put strain on the muscles in the back. As your breasts prepare to feed baby via lactation, they can grow heavier, which can be taxing for your upper back and shoulders. If you work a lot on a computer or bent over a desk, being pregnant can make any resulting discomfort worse. Plus, as baby grows bigger, the center of gravity shifts, which can strain muscles throughout the back, including in the upper back. Some things that you can try to cope with upper back pain include: wear comfortable and supportive clothing, especially bras; gently stretch your back and shoulders daily; maintain a neutral spine while sitting, standing, and sleeping, using the support of pillows or adjusting your desk if needed. 
Low back pain that is not predictive of labor may start early in pregnancy, thanks in part to the loosening of the joints that can start very early in pregnancy. Weight gain, stress, and posture changes exacerbated by your shifting center of gravity can all contribute to lower back pain as your pregnancy continues. Sometimes low back pain comes and goes; sometimes it is a constant dull ache. If you are experiencing lower back pain, you can try applying heat or cold, doing gentle exercise like swimming, yoga, or walking, and sleeping with pillows for support. 
Sciatic nerve pain is a special (and often terrible) kind of back pain. Also called sciatica, this pain comes from pressure being put on the sciatic nerve, which runs on either side of the body from beside the tailbone on the low back out over the hip and down the leg. Sciatic nerve pain can be dull, sharp, burning, or shooting or lead to numbness or tingling in the low back and legs. Sometimes it extends down the leg, sometimes it is only experienced in the low back near the sacrum. Pain may come and go, or it may be present constantly. Sciatica can be one of the most uncomfortable types of back pain to experience. Luckily, there are some stretches that can offer some relief.  Most notably, the figure four stretch, performed as follows:
- Sit upright in a chair.
- With your right foot on the floor and right knee bent at a right angle, bend the left knee and raise the left ankle to cross over the right leg and rest on the right leg just above the right knee.
- Flex the left ankle and, sitting up straight, gently press the left knee slightly down until you feel a stretch in your left hip.
In summary, back pain is common in pregnancy, but is likely not a sign of labor unless it is accompanied by other labor signs or is especially rhythmic or similar to menstrual cramps. If you have concerns about back pain at any time during pregnancy—whether you think it is related to labor or not—you can always talk to your care provider. Sometimes a referral to a specialist, such as a physical therapist, might be appropriate and could help your pregnancy be more bearable.