Lower back pain during pregnancy is extremely common. Roughly three-quarters of pregnant women experience some form of back pain, making it one of the most widespread complaints of pregnancy. While it can range from a dull ache to sharp, activity-limiting discomfort, in most cases it reflects normal physical changes rather than a medical problem.
Why It Happens: The Physical Changes Behind the Pain
Your body undergoes several shifts during pregnancy that put new stress on your lower back. As your belly grows, your center of gravity moves forward. To compensate, many women lean back slightly, which increases the inward curve of the lower spine. This added curvature compresses the small joints along the spine, creating stiffness and pain.
At the same time, your body produces a hormone called relaxin, which loosens the muscles, ligaments, and joints around your pelvis to prepare for delivery. That loosening is necessary, but it also reduces the stability of your back and pelvis, making the area more vulnerable to strain. Relaxin can affect your posture and leave you feeling weak or unstable in your core and lower back, especially as the pregnancy progresses.
Weight gain adds to the load your spine carries, and the abdominal muscles that normally help support your back stretch and weaken as the uterus expands. Together, these changes mean your back is working harder with less support, and pain is the predictable result.
When It Typically Starts
Back pain can appear at any point, but prevalence increases as gestation progresses. Some women notice it in the first trimester as hormonal changes begin loosening ligaments. For most, though, it becomes more noticeable in the second and third trimesters as the belly grows and postural shifts become more pronounced. By the third trimester, the combination of extra weight, altered posture, and ligament laxity is at its peak.
Lower Back Pain vs. Pelvic Girdle Pain
Not all pregnancy-related pain in the back and hip region is the same. True lumbar pain originates in the lower spine and behaves like typical back pain: it worsens or improves with certain movements or positions and may radiate down the leg in a pattern that changes when you bend or shift posture.
Pelvic girdle pain is a separate condition. It’s felt lower, between the back of the hip bones and the buttock fold, often near the sacroiliac joints at the base of the spine. It can also show up at the front of the pelvis, around the pubic bone. Pelvic girdle pain tends to be triggered by weight-bearing activities, walking, climbing stairs, or turning over in bed. Some women experience both types simultaneously.
A study of pregnant women in Ontario found that lumbar pain, pelvic girdle pain, and a combination of both occurred at roughly similar rates, each affecting 15 to 18 percent of women at any given point. Knowing which type you have helps guide the most effective relief strategies, so it’s worth describing the pain location and triggers to your provider.
What Helps: Practical Relief Strategies
Movement and Exercise
Gentle movement is one of the most effective tools for managing pregnancy-related back pain. A simple exercise to try is the cat-cow stretch: start on your hands and knees with your hands under your shoulders and knees under your hips. On an exhale, tuck your tailbone under and let your spine round upward. On an inhale, gently lift the tailbone to create a soft curve in the lower back, letting your chest rise slightly. Repeat for 5 to 10 slow breaths. This mobilizes the spine without placing heavy load on it.
Walking, swimming, and prenatal yoga also help by strengthening the muscles that support the spine and improving circulation. The key is consistency rather than intensity. Short, regular sessions tend to work better than occasional long workouts.
Sleep Position and Pillow Placement
Once your abdomen starts to expand, side sleeping with your knees bent is the recommended position. Placing a pillow between your knees helps align your spine and reduces pressure on the hips. You can also tuck a pillow under your belly or against your lower back for additional support. Full-body pregnancy pillows are designed for exactly this purpose and can make a noticeable difference in overnight comfort.
Daily Habits
Small adjustments throughout the day add up. Wearing supportive, low-heeled shoes reduces strain on the lower back. When standing for long periods, placing one foot on a low stool shifts some of the load off your spine. Sitting with a small cushion or rolled towel behind your lower back helps maintain the natural curve of the spine rather than letting it flatten or slump. When lifting anything, bend at the knees and keep the object close to your body.
Pain Relief Options
Acetaminophen (Tylenol) remains the recommended first-line pain reliever during pregnancy. ACOG, the leading obstetric professional organization in the U.S., reaffirmed in 2025 that acetaminophen is the safest analgesic choice for pregnant women and that current evidence does not support a link to neurodevelopmental disorders in children. The general guidance is to use the lowest effective dose for the shortest time needed. Anti-inflammatory drugs like ibuprofen are generally avoided during pregnancy, particularly after the first trimester.
Signs That Need Prompt Attention
While most pregnancy back pain is benign, certain patterns warrant a call to your provider. Back pain can occasionally signal preterm labor, particularly if it comes in rhythmic waves or is accompanied by pelvic pressure. It can also indicate a urinary tract infection. Contact your care team if your back pain is accompanied by fever, burning during urination, or vaginal bleeding. Sudden, severe pain that doesn’t ease with rest or position changes also deserves evaluation, as does any new numbness or weakness in your legs.
Rhythmic lower back pain that comes and goes at regular intervals, especially before 37 weeks, is different from the steady ache of musculoskeletal strain. If you’re unsure whether what you’re feeling is contractions or muscle pain, timing the episodes for 30 to 60 minutes can help clarify the pattern before you call.