The National Heart, Lung, and Blood Institute (NHLBI), in collaboration with the Eunice Kennedy Shriver National Institute of Child Health and Human Development, is funding this follow-up study of the nuMoM2b cohort to evaluate the association between adverse pregnancy outcomes (APOs) and cardiovascular health approximately 2 to 3½ years postpartum. The study, called the nuMoM2b Heart Health Study or nuMoM2b HHS, utilizes the extensive database and tissue bank developed for nuMoM2b in which nulliparous women are evaluated over the course of pregnancy to study the mechanisms for and prediction of APOs. Women enrolled in the nuMoM2b cohort are extremely well phenotyped through prospective data collection, clinical evaluations, and ultrasound assessments, as well as through the use of standardized definitions. Demographic, psychosocial, dietary, physiologic, and outcome information were collected through maternal interviews, self-administered questionnaires, clinical measurements, ultrasounds, and medical record abstraction. Samples of maternal blood, urine, and cervico-vaginal fluid over pregnancy and cord blood and placenta at delivery were collected and banked. All women completed two sleep questionnaires and over 3,600 had objective overnight sleep studies at two times during pregnancy.