Pregnancy does not make you permanently taller. There is no evidence that pregnancy adds real skeletal height. However, temporary fluctuations in measured height can happen during pregnancy due to changes in posture, joint laxity, and fluid retention. Ironically, the more lasting changes pregnancy causes to your body tend to work in the opposite direction, potentially making you slightly shorter over time.
Why Some Women Measure Differently During Pregnancy
Your measured height can shift by 10 to 20 millimeters (roughly half to three-quarters of an inch) over the course of a single day. Gravity compresses the discs between your vertebrae as you stand and move, so you’re tallest in the morning and shortest at night. One study of young women found daily height variation ranging from 8 to 26 mm. This normal fluctuation means that if you’re measured at a different time of day during a prenatal visit than your last checkup, you might see a “gain” that has nothing to do with pregnancy itself.
On top of that, pregnancy changes your posture significantly. As the uterus grows and breast volume increases, your center of gravity shifts forward. Your pelvis tilts and your lower back curves more deeply inward, a change called increased lumbar lordosis. This postural shift can compress or decompress different parts of the spine in ways that subtly alter a standing height measurement, depending on exactly how you’re positioned against the measuring device.
What Relaxin Does to Your Joints
During pregnancy, your body produces higher levels of the hormone relaxin, which loosens ligaments by activating enzymes that break down collagen in connective tissue. The purpose is to allow your pelvis to widen for delivery. In pregnant cattle, relaxin treatment measurably increased pelvic width and height. In humans, the picture is less clear. Some studies have found higher relaxin levels correlate with greater joint laxity in the pelvis and hips, while others found no such link.
Could this loosening create tiny gaps between vertebrae or decompress the spine enough to add height? It’s theoretically possible as a very small, temporary effect. Relaxin’s influence on peripheral joints like wrists and knees has not been confirmed in human studies, and there’s no direct research showing it increases spinal length. Any effect would reverse after delivery as relaxin levels drop and ligaments regain their normal stiffness.
Pregnancy Is More Likely to Make You Shorter
The more documented change actually works against your height. A study published in the American Journal of Physical Medicine & Rehabilitation tracked 49 women through pregnancy and found that arches permanently flatten afterward. In first-time mothers, foot length increased by an average of 1.4 mm, and arch drop (the amount the arch sags under body weight) increased by about 1 mm. Around 60% of women in the study experienced measurable increases in foot length, with most gaining 2 to 10 mm. About 70% experienced increased arch drop, typically in the 1 to 5 mm range.
These changes were permanent. The first pregnancy appears to cause the most significant flattening, though second pregnancies produced additional (smaller) changes as well. A flatter arch means the sole of your foot sits closer to the ground, which directly subtracts from your standing height. It’s a small amount, a few millimeters at most, but it’s a real and lasting structural change. This is also why many women find they need a half size larger in shoes after having a baby.
What About Growth Plate Reopening?
A persistent idea online is that pregnancy hormones could somehow reopen the growth plates in your bones, allowing you to grow taller the way you did as a teenager. This doesn’t happen. Growth plates fuse permanently in the late teens to mid-twenties, and no pregnancy-related hormone reverses that process. Relaxin loosens soft tissue like ligaments and cartilage, but it does not regenerate the cartilage growth zones in long bones. Once those plates have converted to solid bone, your femurs, tibias, and other long bones are done lengthening for good.
Why the Perception Persists
If you’ve seen women online swearing they grew during pregnancy, a few explanations fit better than actual growth. The most likely is simple measurement variability. A half-inch difference between two height checks months apart can easily come down to time of day, posture, the shoes you took off, or how carefully the measurement was taken. Postpartum posture changes can also play a role: after delivery, some women consciously work on their posture or start exercises that strengthen the core and back, which can make them stand straighter and measure slightly taller than their slouched, late-pregnancy selves.
There’s also a psychological component. Pregnancy brings intense body awareness, and when you’re paying close attention to how your body looks and feels, you’re more likely to notice (or perceive) small differences that were always within normal variation. Without a controlled before-and-after measurement taken at the same time of day under the same conditions, it’s nearly impossible to detect changes of a few millimeters on your own.
The Net Effect on Your Height
Adding it all up: pregnancy can cause tiny, temporary fluctuations in measured height through postural changes and joint laxity, but these resolve after delivery. The one permanent structural change that’s been well-documented, arch flattening, actually reduces your standing height by a few millimeters. So the honest answer is that pregnancy, if anything, is slightly more likely to make you shorter than taller. The changes are small enough that most women never notice them, but “pregnancy made me grow” doesn’t hold up to the evidence.