Something shifts around the halfway mark. The bump becomes obvious. Strangers feel entitled to comment. And your body, which had mostly cooperated up until now, starts behaving in ways that catch you off guard. Hips ache after a short walk. Your knees feel less stable on the stairs. Sitting cross-legged on the floor feels different than it did a month ago. At Cadence Chiropractic in American Fork and Spanish Fork, the team hears these observations from patients in Utah Valley almost every week, and most of them trace back to a hormone that has been quietly active since the first trimester but really makes itself known after 20 weeks. The hormone is relaxin.

What Relaxin Actually Does

Relaxin is produced by the ovaries and the placenta during pregnancy. Its job is to soften connective tissue throughout the body so the pelvis can open enough for delivery. It targets ligaments, the dense cords of tissue that hold bones together at every joint. By relaxing those ligaments, the body becomes more pliable.

The catch is that relaxin does not pick and choose. It does not soften only the ligaments around the pelvis and leave the rest of the body alone. It circulates everywhere, affecting joints from the jaw to the toes. The pelvic ligaments are the most obvious target, but the sacroiliac joints, hip joints, knees, ankles, feet, and even the small joints of the wrists all become looser.

Why 20 Weeks Is the Tipping Point

Relaxin levels rise during the first trimester, plateau, and then continue climbing through the second and third trimesters. By around week 20, the cumulative effect on the joints starts to be noticeable. The combination of higher relaxin, growing belly weight, and a shifting center of gravity means the body is now adapting to looser ligaments while also carrying more load.

The result is that movements that used to feel automatic start requiring more thought. Stepping off a curb, twisting to grab something from the back seat, or standing on one leg while putting on pants suddenly feel less stable. Stairs feel longer. Sitting on the floor with your kids takes more effort to get up from.

What Loose Joints Tend to Feel Like

Patients describe the change in different ways, but a few patterns repeat:

A clicking or popping in the hips and pelvis that was not there before
Sharp catches in the pubic bone when changing direction quickly
Lower back stiffness after sitting, even briefly
Knees that feel like they “give” slightly on the stairs
Aching in the feet and arches by the end of the day
A sense of being more easily thrown off balance

None of these mean something is wrong. They are predictable consequences of relaxin doing its job. They do mean your body is asking for different support than it needed before 20 weeks.

Why Pelvic Alignment Matters More Now

Looser ligaments are easier to move out of place and slower to return on their own. A pelvis that was already slightly rotated before pregnancy can shift further once relaxin reduces the ligament tension that was holding it stable. A sacrum that used to self-correct after a long drive may now stay tilted for days. Small structural imbalances that the body could compensate for in early pregnancy often start producing symptoms in the second half.

This is part of why prenatal chiropractic care often becomes more valuable from 20 weeks onward, even for women who felt fine in the first trimester. The Webster Technique focuses specifically on sacral position and pelvic balance, addressing the joints most affected by relaxin. The Activator Method used at Cadence Chiropractic is precise and low-force, which suits a body whose ligaments are already more mobile than usual. Forceful manipulation is unnecessary and would not match the gentleness pregnancy calls for.

Supporting Loose Joints Between Visits

Daily habits matter more in the second half of pregnancy. A few that tend to help:

Keep the knees together when getting in and out of the car
Avoid standing on one leg while dressing or putting on shoes
Sleep on your side with a pillow between the knees and another supporting the belly
Strengthen the glutes and core gently with prenatal-appropriate movement
Choose supportive footwear and avoid going barefoot for long stretches on hard floors
Move often, but avoid pushing into ranges that feel unstable

Relaxin levels do not drop immediately after birth. They stay elevated for several months, particularly while breastfeeding, which is part of why postpartum recovery has its own structural considerations.

Working With the Hormone, Not Against It

The looseness you start noticing after 20 weeks is not a sign of weakness. It is your body preparing for delivery, working exactly the way it is supposed to. The job is to keep the joints supported and aligned through the changes rather than try to override them. If your body has started feeling different in ways you cannot quite explain, Cadence Chiropractic offers Webster-certified prenatal evaluations in American Fork and Spanish Fork to help you stay aligned, comfortable, and supported through the second half of pregnancy.