Testing Effects of Melatonin on Uterine Contractions in Women

The study will extend recent discoveries that have been made in basic human physiology related to responses melatonin and uterine contractions in late- or full-term pregnant women. The basic physiology work has been conducted in in vitro models of the human myometrium characterizing its responses to melatonin, and in pilot in vivo studies correlating the number of uterine contractions with melatonin concentrations that were manipulated by different types of light exposure. The planned experiments will test a causal link between circulating melatonin levels and uterine contractions in full-term pregnant women by manipulating melatonin levels using exogenous melatonin (i) during the day when endogenous levels of melatonin are very low (Experiment 1), and (ii) during the evening under conditions with lighting that would be expected to suppress the higher evening and nighttime levels of endogenous melatonin (Experiment 2).