Pre-eclampsia, a pregnancy-specific disorder, is the third leading cause of maternal morbidity and mortality worldwide. To develop a device to detect pre-eclampsia in pregnant women living in low resource environments, a method was needed that had to be very low cost and, preferably, easily monitored by the woman herself. Due to the high cost and expertise involved in monitoring the two diagnostic criteria of pre-eclampsia (elevated blood pressure and proteinuria), edema, an indicator of pre-eclampsia, was chosen instead. The general principle of the method is to have each pregnant woman, early in pregnancy, fitted, on either her wrist or ankle, with a detection band, which is set to a preset expansion limit (e.g., expansion by 5%). When edema causes that body part to swell to the limit, the pregnant mother knows that she should seek medical assistance. The resulting prototype device and calibration method require little knowledge and are very durable, cost-effective, and portable.