Rib pain during pregnancy

By trimester

Weeks 1–13

1st trimester

Rib pain is uncommon this early because the uterus hasn't grown enough yet to press upward, though the hormones progesterone and relaxin start loosening the ligaments attaching the lower ribs even before the uterus is noticeably larger. Most rib discomfort this early has another cause, like ordinary muscle strain.

Weeks 14–27

2nd trimester

As the uterus rises out of the pelvis and expands, the rib cage itself starts to widen and its supporting ligaments loosen further, which is when many people first notice rib-area tenderness.

Weeks 28–birth

3rd trimester

This is when rib pain is most common. Research measuring rib cage changes in pregnancy found the angle between the lower ribs widens by about 50% and the rib cage's side-to-side width increases by roughly 2 centimeters by the end of pregnancy, as the uterus pushes up against the diaphragm and rib cage.

What does the evidence show for rib pain?

• The angle between the lower ribs widens by about 50% over the course of pregnancy, and the rib cage's side-to-side diameter increases by roughly 2 centimeters, changes driven partly by the hormones progesterone and relaxin loosening the ligaments that attach the ribs. 1
• These hormone-driven ligament changes affecting the lower ribs can begin even before the uterus has grown large enough to physically press on the rib cage, which is why some rib tenderness can start earlier than the uterus's size alone would suggest. 1
• General musculoskeletal pain in pregnancy, linked to postural and hormonal changes, weight gain, fluid retention, and the enlarging uterus, is reported most often in the third trimester compared with earlier in pregnancy. 2
• Right upper-quadrant abdominal pain, which many people feel as pain under the right ribs, is listed as a symptom of both preeclampsia and eclampsia. 3
• HELLP syndrome, a serious pregnancy complication, classically causes right upper-quadrant or mid-epigastric pain from liver involvement, and severe pain together with abnormal liver findings calls for prompt evaluation, sometimes including a bedside ultrasound, to rule out liver rupture or bleeding. 4

When should I call my provider about rib pain?

Right-sided rib or upper-belly pain that is new, severe, or comes with headache, vision changes, swelling, or nausea needs same-day medical attention: that pain pattern is a listed symptom of both preeclampsia and eclampsia. HELLP syndrome, a related but distinct complication, classically causes the same right upper-quadrant or mid-epigastric pain from liver involvement, and severe pain alongside abnormal liver findings calls for prompt evaluation, sometimes including an ultrasound, to rule out liver rupture or bleeding. Ordinary pregnancy-related rib widening, by contrast, tends to feel like a duller, broader ache across the lower ribs on both sides rather than a sharp, one-sided pain. Trust your read on your own body. If something feels off beyond the list above, please consult your healthcare provider rather than waiting it out.