Pubic Bone Pain in Pregnancy  

Q    Is pubic bone pain normal in pregnancy?

A     From the "Terminal Miseries of Pregnancy," this sounds like something called Symphysis Pubis Diastasis. Now before this nasty-sounding ailment makes you want to set up novenas, know that it's harmless and quite normal.

Here's the deal:

The pelvis is a ring structure. Progesterone, a hormone made in great quantities in pregnancy has many properties besides thickening the lining of the uterus for implantation. It also relaxes smooth muscle, which helps keep the uterus quiet (non-contracting) as the baby grows. A side effect of this is constipation, because it also relaxes the smooth muscle in the intestinal tract.

Progesterone also relaxes the ligaments between joints. In it's wisdom, the human body seeks to make the passageway (the pelvis) a larger space for the passenger (the baby). The middle of the pubic bone is actually a joint where the left and right pubic bones join together. When this loosens up, this in effect makes the diameter of the pelvis a larger space for the baby to negotiate during labor.

So far so good.

But unfortunately, since the pelvis is a ring, if it opens here, it must pinch there. The sacroiliac joints in your lower back to either side of the midline can hurt when this pubic bone separation happens. Or, alternately, you can just hurt at the pubic joint (the "pubic symphysis"). Diastasis is a word meaning "separation," so pubic symphysis diastasis is the normal effect of progesterone and other unknown forces that open up the pelvic ring a little bit for labor.

(An added note: Any pain in this area warrants a pelvic exam to rule out premature dilation of the cervix, and a urine exam to rule out bladder infection.)