The biological process of pregnancy requires significant physical adaptations, particularly around the hips and pelvis. These structural shifts are necessary to accommodate the developing fetus and prepare the body for childbirth. While hip widening is often a source of curiosity or concern, it is a normal alteration designed to facilitate a healthy delivery.
The Role of Relaxin in Pelvic Preparation
Hip widening begins with the hormone Relaxin, produced primarily by the corpus luteum and later by the placenta. Relaxin softens and loosens the body’s connective tissues and ligaments throughout pregnancy, especially those within the pelvic structure. This action targets the pelvic girdle’s main joints: the pubic symphysis and the two sacroiliac joints.
By increasing ligament laxity, the pelvis becomes more flexible, allowing for greater mobility. This flexibility is essential for the pelvis to expand, creating space for the growing uterus and allowing the baby to pass through the birth canal during labor. Relaxin levels surge considerably in the first trimester, and the softening effect continues throughout pregnancy.
Timeline of Noticeable Hip Expansion
Although the hormonal process begins early, the physical sensation or visible change in hip expansion typically occurs later in pregnancy. Relaxin levels peak around 12 to 14 weeks, but this initial softening is often internal and not yet felt. Noticeable hip spreading usually begins in the second trimester, generally starting around 14 to 20 weeks of gestation.
This timing aligns with the rapid growth of the fetus and increasing physical pressure on the pelvis. As the uterus expands, the body’s center of gravity shifts, which, combined with loosened ligaments, can change posture or gait. The most significant hip changes, including differences in how clothes fit, become apparent late in the second and throughout the third trimester.
Addressing Pelvic Girdle Pain and Discomfort
The necessary relaxation of pelvic ligaments can sometimes lead to instability and discomfort, commonly referred to as Pelvic Girdle Pain (PGP) or Symphysis Pubis Dysfunction (SPD). PGP is pain in the pelvic joints, felt over the pubic bone, in the groin, or across the lower back and buttocks. This pain arises because increased joint mobility can cause uneven movement, placing strain on surrounding muscles.
Conservative management techniques can help alleviate this pain. Strategies include maintaining good posture to reduce stress on the pelvis. Wearing a pregnancy support belt can help stabilize the pelvic joints and provide external support. Physical therapy, especially with a women’s health specialist, is often recommended to strengthen the core and pelvic muscles.
What Happens to the Hips After Birth
After delivery, the body begins a gradual recovery process to return to its pre-pregnancy state. Relaxin levels drop quickly following childbirth, signaling the ligaments and joints to begin tightening. This process allows the pelvic girdle to regain stability over time.
The hips substantially return to their former size, though the recovery timeline varies greatly. For many, the largest changes occur within the first six to twelve months postpartum. While ligaments return to their pre-pregnancy state, some women may find their hips remain slightly wider, typically by one to two centimeters, due to the settling of the pelvic joints.