You knew pregnancy was going to mean a lot of firsts — like feeling the incredible first flutter of your baby moving in your belly. But back pain that just won't go away? That might not have been quite the experience you had in mind when you first envisioned yourself with that proverbial pregnancy glow.

While a majority of mothers-to-be experience some dull, throbbing aches in the middle of the back or the butt, some grapple with the searing pain of sciatica during pregnancy, a painful but fortunately temporary condition.[1]

What is sciatica?

sciatica medical illustration

Unlike your average pregnancy back pain, sciatica is a sharp, shooting pain, tingling or numbness that starts in the back or buttocks and radiates all the way down the backs of your legs.

The sciatic nerve, the largest in the body, starts in the lower back, runs down the buttocks and branches down the back of the legs to the ankles and feet[2] In most cases, sciatica happens when this nerve gets compressed by bulging, slipped or ruptured discs, arthritis, or a narrowing of the spinal cord (also called spinal stenosis).

But rarely, women experience sciatica as a short-term side effect of pregnancy.

What causes sciatica during pregnancy?

You can blame sciatica during pregnancy on the usual suspects:

  • Weight gain and increased fluid retention can put pressure on the sciatic nerve where it passes through the pelvis, compressing it.
  • Your expanding uterus might also press down on the sciatic nerve in the lower part of your spine.
  • Your growing belly and breasts shift your center of gravity forward and stretch your lordotic curve (the dip just above your butt). This can cause the muscles in your buttocks and pelvic area to tighten up and pinch the sciatic nerve.
  • Your baby's head can rest directly on the nerve when he starts to settle into the proper birth position in the third trimester.
  • A herniated or slipped disc caused by the extra pressure of your growing uterus can be the culprit, although this is less common.

What you need to know about sciatica during pregnancy

Sciatica will most likely occur during the third trimester, when both you and your baby are bulking up. It can develop earlier, but it's not common. Most women typically experience pain just on one side, though you may feel it in both legs.

Sciatica can be constant or intermittent, depending on the amount of pressure placed on the nerve. Pain may increase as you put on more weight and retain more fluid.

And it can stick around for a few months or so after you've given birth, until you've shed the excess weight and fluid pressing on the nerve.

What you can do to relieve sciatica

  • Use a warm compress. Apply it on the spot where you feel the pain.
  • When you can, take a break off of your feet. Resting in a comfortable position can ease some leg and lower back pain.
  • Sleep on the side of your body that's pain-free. For example, if you feel pain on your left side, lie down on your right side. That's still okay, even though the "best" sleeping position for pregnant women is typically said to be the left side.
  • For extra comfort at night, use a firm mattress with plenty of back support. You can also place a pregnancy pillow or a regular pillow between your legs to help keep the pelvis in better alignment and take some pressure off the sciatic nerve.
  • Try to avoid sitting for long stretches. Take frequent walking breaks, and try alternating between your desk (or the couch) and a Pilates ball. 
  • Do some pelvic tilts with your Kegel exercises. They'll help strengthen your core muscles and can help reduce inflammation.
  • Try swimming. It can take off some of the pressure, since the buoyancy of the water temporarily relieves the spine of the pregnancy weight.
  • Consider acupuncture, chiropractic adjustments or therapeutic prenatal massage. All can potentially offer relief, just be sure to work with a trained and licensed practitioner. Customized physical therapy regimens can be helpful too. 
  • Try to gain pregnancy weight at a steady pace. A sudden jump in pounds could put undue pressure on the sciatic nerve. Your practitioner can recommend how much you personally should gain each trimester. 
  • If the pain is severe, talk to your doctor. He or she may recommend acetaminophen in a dosage that will take the edge off the pain but keep you and your baby safe.