Pelvic instability

During pregnancy, many people report aching around the groin or the back of the pelvis, or a “loose feeling,” as if the pelvis is spreading apart, when standing or walking for a long time. The phrase “pelvic instability” is commonly used to describe this feeling. Rather than meaning that a joint has actually dislocated or moved out of alignment, it is closer to an everyday term for discomfort that occurs when weight is placed through the pelvis.

In healthcare and research, this discomfort is described collectively as pelvic girdle pain (PGP). The term symphysis pubis dysfunction (SPD) was also used in the past, but the current trend is to use the broader term pelvic girdle pain. The same expression is also used by people who are not pregnant to describe discomfort around the sacroiliac joints.

The pelvis undergoes the following changes during pregnancy.

• Hormonal changes: Increased secretion of hormones such as Relaxin makes the ligaments and connective tissues of the pelvis more flexible than usual. This is part of the body’s preparation to widen the birth canal during childbirth. You can read more about this change in Joint laxity during pregnancy.
• A shift in the center of gravity: As the uterus and baby grow, the body’s center of gravity shifts forward, changing the way load is transmitted through the pelvis.
• Increased demands on the abdomen and pelvis: The load on the abdomen and pelvic floor increases.

Together, these changes can cause aching, a feeling of pressure, or sometimes sharp pain around the Pubic symphysis at the front or the Sacroiliac joints at the back. Symptoms may occur on just one side, or both sides may feel uncomfortable.

Discomfort often increases when standing or walking for a long time, climbing stairs, getting out of a car, standing on one leg to put on trousers, rolling over in bed, or spreading the legs apart. It tends to fluctuate throughout the day depending on posture, activity levels, and sleeping position. Many people also report feeling more uncomfortable in the evening.

After childbirth, relaxin levels gradually decrease, and the connective tissues of the pelvis slowly regain their original tension. For most people, discomfort decreases over several weeks to months, although the pace of recovery varies from person to person.

• Try to reduce movements that put your weight on just one leg. Sit down to put on trousers, and climb stairs slowly, one step at a time.
• Try moving with your legs together. Keeping your knees together as you turn your body to get out of a car or roll over in bed reduces the load on the joints.
• Take shorter steps and walk more slowly. If you need to stand for a long time, take seated breaks along the way.
• Try placing a pillow between your knees when sleeping on your side. You can find more positioning tips in Side sleeping and pelvic alignment.
• Try using a Pelvic support belt. It wraps around the pelvis to provide a sense of stability, and many people find it makes activity more comfortable.
• Avoid strenuous exercise or prolonged twisting in one direction, and find an activity level that suits how your body feels.

Rather than excessively tensing up and reducing activity out of worry, it is better to keep moving within a comfortable range.

If the pain becomes progressively worse and makes walking or daily activities difficult, does not settle with rest, or is accompanied by other symptoms such as fever or leg weakness, let your obstetrician or healthcare team know. For more on caring for your body during pregnancy, see Prenatal and postpartum body care.