Sciatica

What It Is & Why It Happens

Sciatica refers to the pain, numbness, tingling, or weakness that radiates along the path of the sciatic nerve, which is the largest nerve in the human body. This nerve branches from the lower back through the hips, buttocks, and down each leg. Sciatica is a common musculoskeletal symptom during pregnancy, particularly in the later trimesters as weight increases.

The primary cause of prenatal sciatica is physical compression. As your uterus expands and your baby grows, the physical weight of the gestation can press directly on the sciatic nerve where it passes through the pelvis.

Additionally, the pregnancy hormone relaxin softens your pelvic joints, which can shift your center of gravity and alter your posture. To compensate for the forward pull of your growing belly, you may lean backward, causing tightness in the piriformis muscle in the buttock, which can squeeze the sciatic nerve (sometimes called piriformis syndrome).

Typical Timeline

Sciatica is most common during the second and third trimesters (specifically between Week 20 and Week 40). This is when fetal growth accelerates, and the baby’s head begins to settle lower in the pelvis (engagement), placing direct pressure on pelvic nerves. Sciatica typically resolves completely in the postpartum period as joint alignment returns to normal and nerve compression is relieved.

Safe Comfort Measures

While you cannot shrink the uterus to relieve the pressure, you can manage the discomfort with these safe, non-medicinal comfort measures:

• Sleep on the Unaffected Side: Sleep on the side of your body that is pain-free. Use a full-body pregnancy pillow or place a firm pillow between your knees and ankles to keep your pelvis level.
• Apply Targeted Heat: Apply a warm compress or heating pad (on a low setting) to your buttock or lower back for 10 to 15 minutes at a time to relax tight muscles. Avoid hot baths or placing heating pads directly on your abdomen.
• Gentle Stretches: Perform gentle stretches targeting the gluteal and piriformis muscles. The seated glute stretch (crossing the ankle of the painful leg over the opposite knee and leaning forward gently) and the cat-cow pose can help relieve tension.
• Avoid Prolonged Sitting: Avoid sitting or standing in one position for long periods. Take frequent breaks to walk around, which keeps the muscles active and prevents nerve compression from tightening.
• Wear Supportive Footwear: Choose flat, supportive shoes with good arch support. Avoid high heels, which shift your pelvis forward and worsen nerve irritation.
• Consult Your Provider: Talk to your OB-GYN or midwife about your pain. They can evaluate your symptoms and recommend a prenatal physical therapist or specialist for pelvic and back alignment.

When to Call the Doctor (Red Flags)

While sciatica is usually a benign musculoskeletal issue, nerve compression can occasionally become severe or mask other serious complications.

Contact your healthcare provider immediately if you experience:

• A sudden loss of bladder or bowel control, or numbness in your groin/perineal area (saddle anesthesia). This is a medical emergency known as cauda equina syndrome.
• Progressive weakness in your leg, foot, or toes, particularly the inability to lift the front part of your foot when walking (foot drop).
• Sciatic pain accompanied by regular, rhythmic abdominal cramping, pelvic pressure, or low back pain before Week 37 (signs of preterm labor).
• Numbness or tingling that spreads to both legs or does not resolve when you change positions.
• Severe, constant pain that prevents sleep or limits your ability to walk even a short distance.