From the moment it cradles a child, the body begins a wondrous transformation. While the Donguibogam explained this via the kidneys and the movement of qi and blood, modern medicine articulates this entire process in the scientific language of hormones, anatomical structures, and biomechanical changes. Low back pain experienced by expectant mothers stems from complex reasons that extend far beyond simply carrying extra abdominal weight.
First and foremost, hormones play a crucial role. The hormone relaxin, which spikes early in pregnancy, acts precisely as its name implies: it relaxes the body. Relaxin begins softening and easing pelvic ligaments and joints so the baby can pass through smoothly during delivery. The problem is that this hormone does not affect the pelvic ligaments alone; it also impacts other ligaments and joints surrounding the spine. As ligaments loosen, spinal and pelvic stability decreases, making it easy to feel pain from even minor movements. You can think of it as similar to screws coming loose from a well-tightened frame. Consequently, approximately 70% of pregnant women suffer from low back pain during pregnancy, with pelvic girdle pain (PGP) being particularly common.
Additionally, as pregnancy progresses, the growing weight of the uterus and fetus shifts the mother's center of gravity forward. To adapt to this shift, the body naturally leans backward, adopting a posture of increased lumbar lordosis, as if struggling to maintain balance. This posture places an immense burden on the muscles surrounding the spine, especially the deep muscle groups of the back and the abdominal muscles. Because the lower back muscles must work twice as hard as normal, they fatigue easily and become stiff, provoking throbbing pain. Conditions such as diastasis recti abdominis—where the abdominal muscles separate—also cause core muscles to weaken, further aggravating low back pain.
Changes in blood circulation cannot be overlooked either. During pregnancy, blood volume increases by up to 50%, and an enlarged uterus can compress major pelvic blood vessels and nerves. This can impede the blood supply to the lower back area or irritate nerves, provoking pain. In addition, venous congestion can affect the nerve roots surrounding the spine.
Even after childbirth, low back pain can persist or newly emerge. This is because the pelvis opens and recovers during the delivery process, and residual effects of relaxin can keep ligaments in a relaxed state. Postures adopted while holding a newborn to breastfeed, everyday motions like lifting and carrying baby supplies, as well as sleep deprivation and stress, place an additional burden on already weakened back and core muscles. This can lead to chronic pain such as postpartum wind syndrome (sanhupung). Sanhupung is a broad concept similar to the deficiency of qi and blood in the Donguibogam, referring to generalized pain that occurs when a postpartum body, already depleted, is exposed to cold qi or emotional stress.
In this way, low back pain stemming from pregnancy and childbirth is not a minor inconvenience, but the outcome of complex, systemic changes spanning the musculoskeletal system, endocrine system, and nervous system. This is precisely why tailored care is necessary according to each individual's physical condition and pain pattern. The vital takeaway is that you should not accept this pain as an unavoidable fate and merely endure it. Understanding your bodily changes and responding wisely is the healthiest choice for both mother and child.
