The Bottom Line

Pregnancy greatly affects the back, its muscles, and the spine; some women may even have to deal with these physical changes long after delivery.

While the female spine has adapted to meet the the demands of pregnancy, this adaptation does not prevent all pregnancy-associated pain, and pregnancy can still take its toll for most women.

The back and spine experience dramatic physical stresses during pregnancy due to extra body weight, larger breasts, a growing uterus, a change in gait and walking pattern, and a shift in a woman's center of gravity. These stressors can cause joint, muscle, and bone pain in the upper and lower back (as well as the shoulders and neck).

While a certain amount of back pain is expected during pregnancy, moderate to severe pain should not be considered “par for the course”, no matter how temporary it may be. If women begin to have back pain in the second trimester (or even earlier), five months of back pain can take a significant affect on a woman's physical and mental health.  

Researchers advocate that women talk to their HCP about their pain, no matter how often women think HCPs hear it. Everyone is unique, and back pain could also be caused by pelvic girdle pain, a UTI, or joint or muscle injury; therefore, all back pain should be assessed by an HCP.

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Background

Male and female spinal structures are different: the female body adapted the structures of the spine for pregnancy; therefore, females have more of a lumbar curve than males.

In addition, three of the lower lumbar vertebrae are interlocked in females (as opposed to two in males) and are therefore stronger than in males.

The distance between the vertebrae is also greater in females and women are able to move further backward to balance the weight from the uterus protruding forward without severely damaging the spine.

Lumbar (lower back); above pelvis

Spinal (Lumbar) Changes

Precise changes to the spine during pregnancy are controversial, as several researchers believe pregnancy increases lumbar (lower spine) curvature, while others do not. Even when lumbar changes were observed during pregnancy, the degree of change was inconsistent.

Not understanding these exact changes hinders treatment plans and guidelines for preventing pain and injury. However, it is challenging to accurately measure spinal changes at the time of pregnancy, since most methods require radiation (x-ray).

If thoracic and lumbar spine curvature do change during pregnancy, pain in the lower back and pelvic region would be expected, and balance and gait pattern would also change as a result. This would cause physical symptoms such as back and pelvic pain, as well as joint pain in the knees, ankles, and feet.

Load

Beginning in the second trimester, weight gain and its change of gravity toward the front can cause pregnant women to arch their backs to move the upper body backward. This increases the load on the facet joints (connections between bones of the spine) and an inward curve increase at the top of the spine (cervical).

Cervical is near the neck, while the thoracic part of the spine is considered the upper back.

Muscles of the lumbar and hip extensors have been shown to work much harder even while a pregnant woman is simply standing, in comparison with postpartum or non-pregnant women. This may be due to a change in core stability:

First, lumbar facet joints are a common source (15% to 45%) of lower back pain in the general population, even before the changes of pregnancy.

When the abdominal muscles stretch to accommodate the enlarging uterus, they weaken and become less effective. This causes muscle fatigue and the spine is left to support the increased weight of the torso, which can cause back pain.

The expanding uterus also puts pressure on the vena cava causing venous congestion (more blood to area than out) in the pelvis and lumbar spine.

All of the above, together, weaken core stability; muscles, joints, and bones that normally do not bear much weight or stress are carrying a much harder load during pregnancy.

Back Pain

Due to the changes described above, back pain is common in pregnancy. Back pain occurs in 50% to 80% of pregnant women, with up to half of those suffering with pain for more than three months, to include postpartum.

Back pain can occur twice as often in women who had back pain before becoming pregnant, and more often in women who have previously been pregnant.

It is theorized that back pain hits women hardest in their first pregnancy, peaks between 18 and 35 weeks of pregnancy, and may be worse at night.

Interestingly, it is noted that a significant proportion of women first experience back pain during the first trimester of pregnancy when physical changes are not yet a factor. 

It is not quite known what causes back pain this early, and even hormones as a cause is debated. Certain hormone levels (such as relaxin) have not been found to be higher in women experiencing lower back pain than those who are not.

Regardless, joints, ligaments, and tendons start loosening in the first trimester to help the musculoskeletal system prepare and adapt for the growing pregnancy (Read Musculoskeletal System).

Sciatica is also likely not a factor, as it is a rare cause of lower back pain during pregnancy. Fortunately, it only appears in about 1% of women, and may be the result of herniation or bulging of a disc which causes compression of the sciatic nerve (the largest nerve in the body), which runs from the lower back down the length of each leg (image below).

Graphic illustration of sciatica pain.

Researchers have noted how very little attention is given to back pain during pregnancy by HCPs. Since it is considered so normal during pregnancy, it is possible that some women may not even bring the problem their HCPs.

Pregnant women do not have to suffer through back pain simply because they are pregnant.

Back pain during pregnancy should not be ignored. It dramatically affects the every day lives of women and can hinder any kind of movement, from light physical activity to standing, sitting, resting, and sleeping.

Low back pain is the most common cause of sick leave after delivery, and management and treatment is crucial to avoid further complications, such as potential disability and a higher risk of postpartum depression.

All back pain needs to be assessed by a HCP.

HCPs can help women manage their back pain and refer them to a specialist of necessary.

Further, although some back pain can be understood to be temporary during pregnancy, back pain may have other causes that need to be immediately assessed and treated. Other causes of back pain during pregnancy include an infection, preterm labor, pelvic girdle pain, urinary tract infection, ectopic pregnancy, or an actual muscle or joint injury and needs to be assessed by a HCP.

Postpartum

For some women, lower back pain can be more severe after delivery. In general, the intensity of the pain usually determines how quickly the pain is relieved. Fortunately, overall results indicate that postpartum lower back pain is temporary, but could take several months.

Women should speak to not only their obstetricians, but seek referrals to other orthopedic specialties who understand back/spinal changes and the treatment and management of back pain resulting from pregnancy.

Postpartum back pain can also be caused by the up to 5% bone density loss that occurs during pregnancy – but this is also temporary.

Long-term studies do not link pregnancy with osteoporosis; however, women in the postpartum should make sure they are obtaining the recommended daily amount of calcium to assist in recovery, especially if breastfeeding (1,000 milligrams/day).

Action

Pregnancy may decrease the ability for pregnant women to change their posture while seated, resulting in women potentially using the same posture every time they sit.

Varied positions can help avoid the same weight and pressure on the same parts of the back and spine for extended periods of time.

The most common technique to manage back and lumbar pain is exercise that can slowly strengthen and tone. Many relevant studies have been published, describing several beneficial types of exercise such as walking, physical therapy, yoga, swimming, and water aerobics.

Pregnant women should talk to their HCP before engaging in any exercising program, especially for back pain. HCPs will need to make sure the pain is not the result of an injury.

Although evidence regarding acupuncture for back pain is conflicting, it is mostly positive, and has minimal potential side effects.

Stabilization belts, massage, relaxation, and prevention of significant weight gain have also been shown to help manage pain.

There are also numerous maternity pillows available in different sizes, shapes, and firmness levels. Women should use trial and error to determine what works best. This will likely change as pregnancy progresses, however, as a position that may have worked earlier in pregnancy may not help the entire pregnancy.

Additional lifestyle tips include wearing low heeled shoes, resting in bed with pillows under the knees with a heating pad, periodic rest periods, and avoidance of standing and sitting for long periods at a time. These same strategies can also help to avoid swelling in the lower body.

Women need to talk to their HCPs before taking any medication during pregnancy, to include acetaminophen (Tylenol®/Paracetamol®). Although acetaminophen is commonly used to control pain during pregnancy, back pain can last longer and require more medication in a shorter time frame than may be advised.

Related pages for additional knowledge include Urinary Tract Infections, Joints and Ligaments, Calcium, Vitamin D, Fatigue, and Sleep.

Partner/Support

Back pain can be debilitating for some women during pregnancy, and partners/support can do a lot to help women through their pain, as well as helping them prevent chronic, longer term pain in the postpartum period.

Back pain can start early in pregnancy, therefore recommendations should not just be applied in the third trimester.

Partners/Support should remind women to:

  • Use proper posture

  • Avoid sitting/standing for long periods

  • Avoid activity that can increase the risk of injury to the back and spine

Offer to change her pillows (over and over again if necessary). Be her emotional support. Massage her upper and lower back, help her apply heat, and walk with her if light physical exercise appears to help either her pain or her sleep. Back pain can lead to a loss of sleep very quickly, which can have compounding effects.

Even when there is nothing partners can do to ease their pain, it can help women a great degree if they know their partner is available, understands their pain, and is there to assist and take over certain responsibilities if necessary.

Gaps

Should first trimester back pain be considered a risk factor for more severe back pain during the third trimester? What interventions can HCPs take to help prevent this in women considered at risk for severe pain?

Resources

Preventing Back Pain: Tips for New Moms (American Orthopaedic Association)

References

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