Common later in pregnancy, but never countedEmerging evidence
The NHS says pain just under the ribs is common in later pregnancy, because the growing baby and womb push up under the ribs. Two NHS trust physiotherapy leaflets for pregnancy call rib pain "very common": often on one side, though it can be both, just under the breast or at the side of the chest, sometimes spreading to the back. The Royal Berkshire leaflet says it usually starts around 27 weeks, and the Calderdale and Huddersfield leaflet that it is most common from 28 weeks. A Dublin maternity hospital calls upper back and rib pain common, especially in the third trimester, and the UK's pelvic health physiotherapists (Pelvic, Obstetric and Gynaecological Physiotherapy, POGP) say muscle and joint symptoms in pregnancy are most likely then.
No study has measured how common it is. A German hospital team searching the main research databases for a 2025 paper found no more than "a couple of results" on rib pain and nerve pain between the ribs in pregnancy, many of them old case reports. The nearest studies asked about the back in general: in 184 Turkish women asked at each trimester's visit, pain in the "back" region of a body chart, separate from the low back, was reported most in the third trimester, and in an Israeli survey of 589 pregnant and 1,062 non-pregnant women, upper back pain was common in both groups and the difference disappeared once age, weight, work and health were taken into account. Neither asked about the ribs, so this guide gives no percentage.
Sources 1, 2, 3, 4, 5, 6, 7, 8
Why it happens: the rib cage changes shapeStrong evidence
As the womb grows, the lower rib cage widens. The angle where the lower ribs meet under the breastbone opens from about 68.5 degrees early in pregnancy to 103.5 degrees by the end of it, and the resting diaphragm sits about 5 cm higher, figures from older studies that a 2015 review quotes; the lower rib cage is wider in the third trimester than after the birth. In two small studies of 18 women each, the rib cage changed shape but not volume, the lungs weren't squashed, and the breathing muscles kept their strength. A 2022 review adds that hormones drive these chest wall changes most in the first weeks of pregnancy, and the growing womb most in the last trimester.
Feeling out of breath is common too: 70% of healthy pregnant women report it, starting in the first trimester, before the bump could explain it, the 2015 review says. The NHS says it's common, but breathlessness that comes on suddenly, when you lie down, or with chest pain or dizziness needs checking immediately. POGP calls the discomfort over the lower ribs "ribflare", from "your growing baby pushing your ribs away from their normal position", and an NHS obstetric physiotherapy service lists rib flare among the problems it treats. Our rib flare page uses the term for the shape of the lower ribs instead.
Sources 9, 10, 11, 12, 13, 14, 15
The baby, your breasts, slumped sitting and heartburnEmerging evidence
The leaflets name the baby's kicks and changes of position, which press on the ribs; a breech baby's head wedged under the ribs, felt on that side just below the breast or at bra-strap level at the back (the Dublin leaflet); growing breasts, whose weight, and the rounded shoulders that can come with them, strain the rib cage; and hormones that soften the ligaments, so the rib joints may move a little more. Sitting, especially slumped or leaning forward, shortens the distance between your pelvis and rib cage and can make rib pain worse, the leaflets say (the Royal Berkshire leaflet adds heartburn), while standing lengthens the trunk. None of these explanations has been tested, and our research found no study of kicks or a breech baby and rib pain.
Heartburn is common in pregnancy, more so from 12 weeks onwards and in the later stages, the NHS says: a burning feeling or pain in the chest, often behind the breastbone, with fullness, burping or bringing food up, usually soon after eating. The leaflets say it is sometimes felt as rib pain. In 263 pregnant women followed through pregnancy, new reflux symptoms began in about a quarter in each trimester (25.8%, 24.3% and 25.5%).
Sources 2, 3, 4, 14, 16, 17, 18
Less common: the upper back, costochondritis, a nerve, a cracked rib or shinglesEmerging evidence
Pain at the back of the ribs or between the shoulder blades is usually the upper back: a stiff ache after long sitting that eases as you move, which the Dublin leaflet covers alongside rib pain and our back pain in pregnancy guide covers in full. Costochondritis causes chest pain beside the breastbone that gets worse when you move, lie down, breathe deeply or press on your ribs, and it can last a few weeks to several months, the NHS says; the Royal Berkshire leaflet names it among the causes in pregnancy, but there are no figures for how often.
An irritated nerve between two ribs (intercostal neuralgia) is uncommon: one German university hospital treated 17 pregnant women for it over about 7 years, at an average of 31 weeks, 10 of them on the right and 13 below the lowest three ribs. It was diagnosed when pressing one spot between two ribs brought on the worst of the pain, and the paper describes the pain as stabbing, shooting or burning. Five of the women had first been treated for a suspected kidney infection. A rib cracked by a long coughing fit, or with no clear injury, is rare and known only from case reports; an X-ray isn't always needed, and pain relief is the usual treatment. Shingles can start as a tingling or painful patch of skin on one side a few days before the rash, and rarely comes without one.
Sources 4, 19, 2, 6, 20, 21, 22
Pre-eclampsia: uncommon, and the reason pain under the ribs gets a callStrong evidence
The NHS says pain just under the ribs is common later in pregnancy, but if it is bad or persistent, particularly on the right, it can be a sign of pre-eclampsia, a pregnancy condition that causes high blood pressure. The NHS's full list of its symptoms is a severe headache that doesn't go away with simple painkillers, vision problems such as blurred vision or seeing flashing lights, pain below the ribs, sudden swelling of the face, hands or feet, feeling very unwell, heartburn that doesn't go away with heartburn medicines, and being sick; the National Institute for Health and Care Excellence (NICE) words the rib sign as "severe pain just below the ribs". Pre-eclampsia is most likely from 20 weeks, though it can happen at any point in pregnancy, and it can develop in the days or weeks after the birth. Any of these symptoms needs checking immediately: if you're pregnant, call your maternity unit, and if you've recently given birth or can't reach the unit, call 111.
Pre-eclampsia complicates 2% to 8% of pregnancies worldwide, and high blood pressure in pregnancy affects about 8% to 10% of pregnant women. "In most cases pre-eclampsia is not severe", the NHS says, and fewer than 1 in a million women giving birth in the UK now die from it, NICE says. HELLP syndrome (haemolysis, elevated liver enzymes and low platelets), which the NHS calls a rare liver and blood disorder, affects 0.5% to 0.9% of pregnancies and 10% to 20% of women with severe pre-eclampsia. About 70% of cases start before the birth, mostly between 27 and 37 weeks, and the rest within 48 hours after it. Its pain is in the right upper tummy or the upper middle, can come and go like colic, often with feeling or being sick, and many women have felt generally unwell for some days before, a review says.
Sources 1, 23, 24, 25, 26, 27
Gallstones and the liver: itching is the clueStrong evidence
Gallstone pain is severe and constant, lasts more than 30 minutes and can last several hours, sits in the middle of the tummy or just under the right ribs, can make you feel or be sick, and is sometimes set off by fatty food. In 3,254 women scanned through pregnancy at one military hospital, new gallbladder sludge or stones appeared in 5.1% by the second trimester, 7.9% by the third and 10.2% by 4 to 6 weeks after the birth; many cleared again, and 0.8% had the gallbladder removed within a year. In one community hospital, 220 of 228 pregnant women with gallbladder disease were treated without an operation; symptoms came back after the birth in 77%, mostly leading to surgery then, with no complications for mother or baby in either group.
Obstetric cholestasis, or intrahepatic cholestasis of pregnancy (ICP), is a liver condition of pregnancy that shows as itching rather than pain: itching with no rash, which may include the palms and soles, tends to be worse at night and usually starts after 28 weeks. It affects about 7 in 1,000 pregnant women in the UK, and up to 15 in 1,000 of Indian-Asian or Pakistani-Asian origin, while itching itself affects about 25 in 100 pregnant women, most of whom don't have ICP. Neither the NHS nor the Royal College of Obstetricians and Gynaecologists (RCOG) lists pain as a symptom. Severe ICP carries a small risk of stillbirth (around 3 in 100 women with severe ICP after 36 weeks, the RCOG says), which is why it needs urgent help, extra checks and sometimes an earlier birth; most women with ICP make a full recovery and have a healthy birth, the NHS says. Acute fatty liver of pregnancy is very rare: 5.0 per 100,000 women giving birth in a UK national study.
Sources 28, 29, 30, 31, 32, 33, 34
A kidney infection, clots and the heart: rare, with their own signsStrong evidence
A kidney infection brings pain in your back or side under the ribs with a high temperature, shivering or pain when you pee, and the NHS asks pregnant women with its symptoms to get an urgent GP appointment or help from NHS 111; in pregnancy, antibiotics may be given through a drip in hospital. It complicated 0.5% of 543,430 pregnancies in one US health system and 1.4% of pregnancies in one hospital, and in a Jamaican hospital series, 96% of women had pain in the loin (the side of the back below the ribs), more often on the right (67%).
Blood clots are uncommon, affecting 1 to 2 in 1,000 women in pregnancy or the first 6 weeks after the birth, with the highest risk just after the birth, and a clot in the lungs before the birth affects about 1.3 in 10,000 women giving birth in the UK. A heart attack in pregnancy or the week after the birth is very rare, 0.7 per 100,000 women giving birth in the UK (25 women in 2005 to 2010), and a tear in the main artery (aortic dissection) is rarer still, 5.5 per million in pregnancy and the 3 months after in US data. They matter because, although maternal deaths are rare (about 13 in every 100,000 women giving birth in the UK in 2022 to 2024), clots (42 women) and heart disease (39 women) were the two commonest causes. A heart attack can feel like indigestion, so sudden chest pain or discomfort that doesn't go away, or that spreads to an arm, the neck, jaw or back, needs a 999 call.
Sources 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46
When a scan or test helpsStrong evidence
Rib pain from the bump, the baby and the upper back changes with position and posture, eases when you sit tall or stretch up, and comes with nothing else. It is recognised from the story and an examination, without a scan: NHS Borders asks its clinicians to point women to rib pain information first rather than refer straight to physiotherapy, and even a rib cracked by coughing often doesn't need an X-ray when the signs are clear. The Royal Berkshire leaflet's own summary is fair: the serious conditions "are rare, and most pregnancy related rib pain is common and not serious".
Tests answer specific questions: blood pressure and pee checks at your routine antenatal appointments, and, if pre-eclampsia is suspected, hospital tests that can include a blood test and scans of your baby's growth; blood tests for HELLP syndrome; blood tests of liver function and bile acids for itching that could be ICP; an ultrasound scan of the gallbladder, which uses no X-rays, for suspected gallstones; a urine test for a suspected urine or kidney infection; and an ultrasound scan of the leg within 24 hours for a suspected clot. A suspected heart problem or clot in the lungs is checked in hospital, after a 999 call. Nerve pain between the ribs is diagnosed only after a kidney infection, pre-eclampsia and heart problems have been ruled out as needed.
Sources 2, 14, 47, 20, 23, 27, 33, 48, 28, 30, 35, 49, 50, 41, 46, 6
Stage by stage, and how it usually goesEmerging evidence
First trimester (to about 12 weeks): rib pain is less typical this early, as the leaflets place it from about 27 or 28 weeks. Feeling out of breath can start now, and indigestion becomes more common from 12 weeks. Pain in the tip of the shoulder with sudden severe tummy pain, dizziness or fainting can be an ectopic pregnancy, which affects about 1 in 90 pregnancies in the UK, usually with symptoms between 4 and 12 weeks: that is a 999 call.
Second trimester (about 13 to 27 weeks): rib pain often starts towards the end, around 27 weeks, as the lower rib cage keeps widening. Kidney infections were most common in the second trimester in one hospital (53% of 440 cases), and pre-eclampsia is most likely from 20 weeks.
Third trimester (28 weeks to the birth): the most rib pain, with the largest bump, the diaphragm higher and the rib cage at its widest; kicks, a breech baby's head under the ribs and heartburn add to it. Around 95% of babies are head down by 37 weeks. The itching of ICP usually starts after 28 weeks, and HELLP syndrome peaks between 27 and 37 weeks. Appendicitis is rare at any stage, 1 in 1,493 pregnancies in one hospital, and even in the third trimester pain low on the right was the commonest symptom it started with (10 of 13 women). Studies disagree on whether the appendix moves up towards the ribs late in pregnancy: two scan studies and one study at surgery found it higher, while two studies at caesarean or surgery found it in its usual place in most women.
Rib pain often lasts to the end of pregnancy. One maternity hospital says relief usually comes after about 36 weeks, when the baby drops into the pelvis, but the NHS names only heartburn, indigestion and needing to pee as symptoms that may ease then, and some babies don't move down until labour starts. After the birth, the lower rib cage narrows again, POGP says most pregnancy muscle and joint symptoms improve, and heartburn often goes, though it can continue. Pre-eclampsia can still develop in the days or weeks after the birth, about 30% of HELLP syndrome starts within 48 hours of it (our arithmetic from the review's 70% before), and clots are most likely just after the birth. Feeding, lifting and carrying can keep the upper back sore. No study has followed rib pain after the birth, and no one can promise a timescale.
Sources 2, 3, 9, 16, 51, 37, 23, 4, 52, 33, 27, 53, 54, 55, 56, 57, 58, 5, 59, 60, 39
