Pelvic Girdle Pain (PGP) is reported by 50% of pregnant women and up to 11 years after pregnancy, 10% of women have persistent and per definition chronic PGP. Central (nervous system) sensitization that elicits pain hypersensitivity, may be one explanation. The overall aim of this study is to explore features of central sensitization in pregnant women and its predictive ability on physical activity, functioning and health in women with PGP. Measurements of central sensitization will be done on two study groups, pregnant women with PGP and healthy controls. To identify women at risk to develop chronic pain in relation to a common pain experience ie PGP in pregnancy, may help us understand if central sensitization early in life explains why women develop chronic pain.