To investigate pregnancy outcome in patients who conceived with an intrauterine contraceptive device. A retrospective study comparing the pregnancy outcome of women with retained intrauterine device (n = 98), patients after intrauterine device removal in early pregnancy (n = 194), and pregnancies without an intrauterine device (n = 141,191) was performed. A significant linear association was documented among the 3 groups and adverse outcomes such as preterm delivery (18.4% in the retained intrauterine device, 14.4 % in removed intrauterine device, and 7.3% in the no-intrauterine device group; P < .001) and chorioamnionitis (7.1% in the retained intrauterine device, 4.1% in removed intrauterine device and 0.7% in the no-intrauterine device group; P < .001). The presence of retained or removed intrauterine device was found as an independent risk factor for both preterm delivery and chorioamnionitis in multivariable models. Women conceiving with an intrauterine device are at increased risk for adverse obstetric outcomes, whereas the risk is higher for pregnancies with retained intrauterine device compared with early intrauterine device removal.