Knee pain during pregnancy is very common and usually happens because your body is preparing to support the growing baby. Extra weight puts more pressure on your joints, and pregnancy hormones loosen the ligaments, making the knees feel weak or painful. Water retention can also add stiffness. Staying active with gentle exercises, using proper footwear, and avoiding long standing usually helps. If the pain becomes severe, swelling increases, or you have difficulty walking, it is best to get checked by your doctor.