The question of whether the pelvis can get wider is a common one, often driven by body image concerns. While the adult skeleton is generally considered mature and set, research shows that the pelvis, the large bone structure at the base of the spine, is more dynamic than previously understood. This guide explores the different ways the pelvis can change size and what factors are actually at play.
The Anatomy of the Pelvis
The pelvis is a basin-shaped structure composed of four bones: the left and right hip bones (innominate bones), the sacrum, and the coccyx. The two hip bones connect at the front via the pubic symphysis and at the back to the sacrum via the sacroiliac joints. These joints are connected by strong ligaments, but they are not completely rigid. The overall width and shape of the pelvis are genetically determined, but external factors influence its changes throughout life.
Hormonal Influences During Puberty and Pregnancy
For females, the pelvis undergoes significant and targeted widening during two key life stages, driven by hormones.
Puberty
During female puberty, rising estrogen levels cause the pelvis to expand. This anatomical change is an evolutionary adaptation, preparing the body for the possibility of childbirth by creating a wider and more oval-shaped pelvic inlet. The growth is rapid during adolescence and is largely complete by the early twenties, with the female pelvis becoming distinctly wider than the male pelvis.
Pregnancy and Childbirth
Pregnancy triggers a second wave of pelvic changes. The body produces a hormone called relaxin, which softens and loosens the ligaments and connective tissue throughout the pelvis. This allows the pelvic joints, including the pubic symphysis at the front and the sacroiliac joints at the back, to stretch and provide extra room for the baby during birth. While this widening is temporary and the joints tighten up postpartum, some women may experience a slight and permanent increase in hip width. For some, this process can cause significant pain and instability, a condition known as symphysis pubis dysfunction (SPD).
Pelvic Widening in Adulthood and Later Life
Even after puberty and skeletal maturity, research shows that the pelvis continues to undergo slow, subtle changes over a person's lifetime. A 2011 study published in the Journal of Orthopaedic Research found that the pelvic bones of both men and women continue to grow wider with age.
Researchers used CT scans to measure the pelvises of individuals aged 20 to 79 and found an average increase in pelvic width of nearly an inch over this period. This widening occurs at the pelvic inlet and is a result of continued bone remodeling, not just fat accumulation.
Exercise and Pelvic Width: Separating Fact from Fiction
Many people believe they can widen or narrow their pelvic bone structure through specific exercises. This is a common misconception.
- Bone Structure is Fixed: You cannot change your underlying bone structure with exercise. While muscle and fat distribution can be altered, your skeletal frame is determined by genetics and developmental factors.
- Targeting the Appearance: Exercises can, however, change the appearance of your hip width by building muscle, especially the gluteal muscles, and by reducing overall body fat. Here is a list of exercises that can help tone the muscles around the hips:
- Squats
- Lunges
- Hip thrusts
- Side-lying leg raises (hip abduction)
- Clamshells
The Role of Genetics and Body Composition
Why do some people naturally have wider hips than others? The answer often lies in a combination of genetics and body composition.
- Genetic Predisposition: Your inherited genes play a major role in determining the shape of your skeleton and how fat is distributed on your body. Some people are genetically predisposed to carrying more fat around their hips and thighs, creating a curvier appearance.
- Body Fat Distribution: The amount of subcutaneous fat (fat stored just under the skin) around the hips can significantly affect how wide the area appears. Weight fluctuations can change your apparent hip width, though not the bone structure itself.
- Hip Dips: The presence of hip dips, or violin hips, is also related to the unique structure of your pelvis and femur. They are a normal anatomical feature and are not indicative of health or fitness level.
Pelvic Widening vs. Perceived Changes
| Feature | True Pelvic Widening (Bone) | Perceived Pelvic Widening (Appearance) |
|---|---|---|
| Cause | Hormonal changes (puberty, pregnancy); Bone remodeling with age. | Changes in muscle mass (e.g., glutes); Changes in body fat distribution; Weight gain or loss. |
| Modifiable? | Not modifiable through exercise or diet; influenced by genetics and life stages. | Modifiable through exercise and diet, targeting body composition. |
| Permanence | Can be permanent (post-pregnancy) or gradual over time (aging). | Dependent on lifestyle and can change with diet and exercise habits. |
| Gender Specific | Pronounced changes in females during puberty and pregnancy due to hormones; subtle changes with age in both sexes. | Affects all genders, but hormonal differences influence fat storage patterns. |
Conclusion: Understanding and Accepting Your Body
Understanding how and why your pelvis can get wider provides a more accurate view of your body's capabilities and changes. While exercise cannot change your inherent skeletal structure, it can certainly influence the shape and strength of the surrounding muscles. For women, puberty and pregnancy are periods of significant hormonal shifts that directly impact pelvic dimensions. For everyone, the pelvis widens subtly with age, proving that our bodies are in a constant state of flux. By focusing on overall health through diet and exercise rather than trying to manipulate bone width, you can achieve your best possible body composition and embrace your unique anatomy. For accurate medical advice, it is always recommended to consult a healthcare professional. For more information on age-related bone changes, resources from institutions like the National Institutes of Health can be helpful.
