SPD (Symphysis Pubis Dysfunction)

Symphysis pubis dysfunction (SPD) is pelvic joint pain during pregnancy caused by the loosening of the symphysis pubis ligament — the joint at the front of the pelvis where the two halves of the pelvic bone meet.

What causes SPD

During pregnancy, the hormone relaxin softens the body’s ligaments to allow the pelvis to expand for birth. In some pregnancies, this softening is more pronounced or asymmetrical, causing the symphysis pubis joint to become unstable. The result is a sharp, often searing pain at the pubic bone, the inner thighs, and sometimes the lower back and sacroiliac joints.

SPD affects an estimated 1 in 5 pregnancies to some degree. Severe SPD — sometimes called pelvic girdle pain (PGP) — affects a smaller proportion but can be severely disabling.

Why SPD makes sleeping difficult

When you side-sleep without anything between your knees, the upper leg drops forward and rotates the pelvis through the loosened symphysis pubis joint. Each small rotation creates a micro-movement at the joint. Over hours of sleep, those micro-movements produce the searing pain that wakes many SPD sufferers at 3-4am.

What helps (and what does not)

What may help:

• A pillow between the knees maintaining pelvic neutrality (first-line non-pharmacological recommendation, Cleveland Clinic)
• A wedge under the bump reducing forward pull
• Keeping both knees level rather than one higher than the other

What does not help (or makes it worse):

• Side sleeping with knees together and one leg forward
• Getting in and out of bed with asymmetrical weight bearing (step both legs out simultaneously)
• Long periods standing on one leg

What pillows do: A full-body U-shaped pillow (like the Momcozy or PharMeDoc) maintains knee separation on both sides simultaneously, which means the benefit persists even when you roll from left to right in your sleep. A C-shaped pillow (like the Snoogle) provides knee separation on one side — if you roll to the other side, you lose the knee gap.

When pillows are not enough

If your SPD pain does not respond to positional support within 2-3 weeks, or if the pain is severe enough to interrupt sleep consistently, this is a physical therapy referral situation, not a pillow-selection situation. A women’s health physiotherapist can provide targeted exercises, a pelvic girdle belt, and gait modification advice that pillows cannot.

Always consult your midwife or OB about sleep positioning recommendations during pregnancy, especially if you have complications.

Relevant NHS and ACOG guidance

The NHS recommends sleeping on your left side from 28 weeks. For SPD, maintaining a neutral pelvis in that position is more important than the side itself. ACOG does not have specific pillow guidance for SPD, but both bodies recommend physiotherapy assessment for pelvic girdle pain.