Why do we have pelvic pains when pregnant?

$1,000,000 question: There's a lot of increased pressure in pregnancy, and venous swelling and congestion. Your pelvic ligaments are stretched, your body is releasing a hormone called 'relaxin' which is doing just that.... Relaxing the ligaments holding your pelvic bones together. Some women's pelvic bones separate by as much as 1cm in pregnancy.... That's a lot of stretching! most women have pain, you're not alone!