Presence of any obstetric or maternal complication after the first trimester of pregnancy, i.e. spontaneous abortion, intrauterine fetal death, termination of pregnancy, oligohydramnios, premature delivery or intrauterine growth retardation. Spontaneous abortion is defined as spontaneous expulsion of the embryo or the fetus before 16 weeks of gestation. Oligohydramnios is defined as the ultrasonic measurement with an amniotic index <=5 cm. IUGR is defined as a fetal birth weight less than the 10th percentile for gestational age, according to the national reference curves.