Abstract: In an apparatus and method for measuring in vitro the concentration of meconium in amniotic fluid, a plurality of sensors are placed in predetermined locations throughout an amniotic sac. Each sensor includes a blue light-emitting diode having a peak transmission wavelength centered at about 430 nm, a transducer comprising a blue-enhanced photodiode for converting the light received from the light-emitting diode to a voltage signal, and an operational amplifier for amplifying the voltage signal. The light source and transducer are spaced a predetermined distance relative to each other, and define an amniotic fluid passageway therebetween for receiving the amniotic fluid. A micro-controller calculates, in accordance with an empirically-determined linear equation, the meconium concentration based on the natural log of each transducer signal.