The Pregnancy Mobility Index: a mobility scale during and after pregnancy

Background. During pregnancy, every second woman will experience some degree of back or pelvic pain. While several validated instruments to assess back pain exist for the general population, these are not suitable for application in a pregnant population and have not been validated for this purpose. A pregnant population not only differs from the general population regarding the type of back pain - frequently a pelvic girdle component is added - but pregnant women also have different mobility patterns and expectations. We therefore present in this study a self-report mobility scale specifically designed for a pregnant population: the Pregnancy Mobility Index. Methods. Longitudinal cohort study including 672 nulliparous women with a singleton low-risk pregnancy. The Pregnancy Mobility Index consists of items concerning day-to-day activities selected through literature research and clinical experience. Participating women completed the questionnaire at 12 and 36 weeks' gestation and one year after delivery. Reliability, construct and criterion validity were tested. Results. The internal consistency (Cronbach's alpha) was 0.8 or higher. The Pregnancy Mobility Index scales correlated best with the physical and pain scale of the RAND-36, indicating a good construct validity. The assumptions that the Pregnancy Mobility Index scores increase during pregnancy and decrease after delivery and that women with back or pelvic problems scored higher on the Pregnancy Mobility Index domains than women without back or pelvic pain were confirmed, indicating a good criterion validation. Conclusion. The Pregnancy Mobility Index has been shown to be a reliable and valid questionnaire well suited for use during and after pregnancy.