One aspect of the invention provides a fetal pulse oximeter including: a shape-memory member adapted and configured to expand outward and define a loop when advanced out of a cannula； one or more light sources mounted on the shape memory member and facing toward a center of the loop, the one or more light sources adapted and configured to generate red and infrared light； and a photodiode mounted on the shape memory member and facing toward a center of the loop. Another aspect of the invention provides a method for measuring recording pulse and blood oxygen saturation. The method includes: advancing the fetal pulse oximeter as described herein out of a cannula within a placenta； allowing the shape-memory member to expand outward； and placing the loop over a limb.
