In this study, healthy women and those at high-risk of adverse pregnancy outcomes (pre-eclampsia, fetal growth restriction, gestational diabetes) were selected to assess the effect of fatty acid supplementation. The purpose of this paper is to report two novel findings (i) at recruitment the receiver operating characteristic (ROC) for erythrocyte oleic acid predicted spontaneous delivery at 34 weeks gestation (ROC=0.926 n=296) for all women entering the study. Further analysis revealed oleic and all monounsaturated fatty acids were similarly predictive with or without a supplement during the pregnancy. (ii) At delivery, we observed a biomagnification of saturated fatty acids from mother to fetus with the reverse for monounsaturates. The major conclusions are (i) the status of the mother in the months prior to conception is a stronger predictor of preterm delivery than the events during the pregnancy. (ii) Saturated fats may be playing an important function in supporting fetal membrane growth.