The common advice to avoid crossing one’s legs during pregnancy is a long-standing caution rooted in the significant physiological and mechanical changes that occur during gestation. The growing fetus, hormonal shifts, and alterations to the circulatory system all contribute to making the act of crossing the legs a potential source of discomfort and, in certain cases, a minor risk factor. Understanding the specific bodily systems affected clarifies why this guidance persists for expectant mothers.
Impact on Circulation and Vein Health
Pregnancy causes a substantial increase in the body’s blood volume, which can rise by up to 50% to support the growing baby and uterus. This increased volume puts greater pressure on the veins in the lower extremities, which must work against gravity to return blood to the heart. The expanding uterus also physically compresses the inferior vena cava, the large vein carrying blood from the lower body back to the heart, further impeding venous return.
Crossing one leg over the other adds a direct, external point of pressure on the femoral veins in the thigh and behind the knee. This compression significantly slows blood flow, causing blood to pool in the lower legs and ankles. The resulting venous stasis can worsen common pregnancy-related swelling, known as edema.
A more serious concern is Deep Vein Thrombosis (DVT), the formation of a blood clot in a deep vein. Pregnancy inherently increases the risk of DVT by four to six times due to hypercoagulability, a natural adaptation to prevent excessive bleeding during delivery. Prolonged periods of sitting with the legs crossed compounds this heightened risk by mechanically obstructing the already challenged blood flow, a primary factor in clot formation.
Effects on Posture and Pelvic Alignment
Musculoskeletal changes during pregnancy are profound, particularly due to the hormone relaxin, which is released to soften and loosen the ligaments in preparation for childbirth. While this hormonal action facilitates delivery, it also destabilizes the joints of the pelvis and lower back, making them more vulnerable to strain and misalignment. The weight of the growing uterus also shifts the center of gravity forward, forcing an exaggerated curve in the lower spine.
Sitting with the legs crossed forces the pelvis into an asymmetrical, rotated position, placing uneven weight and strain across the already loose pelvic joints and ligaments. This uneven posture can exacerbate existing lower back pain, hip discomfort, and a condition known as pelvic girdle pain (PGP). The mechanical strain can also affect the piriformis muscle, potentially irritating the sciatic nerve and contributing to or worsening common pregnancy-related sciatica.
Maintaining an asymmetrical posture can also put tension on the uterine ligaments that support the expanding uterus. For women with pre-existing conditions like symphysis pubis dysfunction (SPD) or PGP, crossing the legs is specifically advised against to prevent increased pain and joint instability. The goal is to encourage neutral, symmetrical alignment to minimize stress on the pelvic structures.
Current Medical Perspective and Alternatives
The current medical consensus views the avoidance of crossing legs as a comfort and preventative measure, rather than a strict mandate that poses immediate danger if done briefly. Occasional, short periods of leg crossing are unlikely to cause significant harm for most healthy pregnant individuals. The primary concern arises when the position is maintained for long durations, particularly in the later stages of pregnancy when circulatory and musculoskeletal stresses are highest.
For women already at a higher risk for DVT or those experiencing significant edema or pelvic pain, prolonged leg crossing should be avoided to mitigate combined physiological risk factors. The advice has shifted away from older concerns about blood pressure spikes and is now focused on preventing venous stasis and promoting musculoskeletal comfort. Healthcare providers recommend adopting specific, safer sitting alternatives to support circulation and alignment.
Instead of crossing the legs, expectant mothers are advised to sit with both feet flat on the floor, keeping the ankles uncrossed and the knees slightly lower than the hips. Using a footrest or elevating the feet periodically can significantly improve venous return and reduce swelling. Another beneficial alternative is the “tailor sitting” or “criss-cross applesauce” position on the floor, which can help strengthen the pelvic muscles and open the hips, provided it does not cause discomfort or aggravate existing pelvic pain.