Towards an Integrated Third-Trimester Screening in Pregnancy

cy. Indeed, the role of the placenta in late-onset PE and IUGR is still in need of clarification. Late-onset PE seems to be much more dependent on the influence of maternal factors, and a proportion of cases occur with normal uterine artery Doppler and angiogenic factors, and consequently with a normal placenta [4] . On the other hand, abnormal fetal growth late in pregnancy is probably a common diagnosis for several entities, some of which seem to be related with abnormal placentation while others do not [5] . Despite an overall lower rate of severe complications, the prevalence of late pregnancy PE and IUGR is much higher than that of earlier forms and this results in an important impact on pregnancy outcomes and incurred costs [6] . In addition, serious complications still occur. Severe PE and/or HELLP syndrome at term is certainly possible, with important consumption of resources and the risk of severe maternal complications. Likewise, unrecognized (early and) late-onset forms of IUGR are still today estimated to be involved in more than 50% of stillbirths [7] . It seems clear that, at least with current means, improving prediction of late-onset PE and IUGR cannot be achieved early in gestation. However, a different approach that comes closer in time to the onset of the disease should improve the detection rates. Is that worthResearch during the last 20 years has largely focused on the development of screening approaches allowing the diagnosis of preeclampsia (PE) and intrauterine growth restriction (IUGR) as early as possible in pregnancy [1] . We know today that this is only possible with a high accuracy for the early-onset forms. Poor early pregnancy placentation has a causal association with the early-onset forms of these diseases [2] , which actually often present together. Abnormal placentation can be detected by increased uterine artery Doppler and by reduced levels of angiogenic placental proteins such as placental growth factor. Evidence has demonstrated that first-trimester screening strategies combining maternal baseline factors, uterine artery Doppler and maternal biomarkers can be extremely powerful to detect the early-onset, severe forms of PE and IUGR, with detection rates in excess of 90 and 75%, respectively [1] . Early detection of high-risk patients opens opportunities for early therapy that might reduce the risk or delay the onset of these complications [3] . However, first-trimester strategies have normally shown poorer predictive values for late-onset forms of PE and IUGR. This has normally been attributed to the milder nature of the disease, where changes can possibly not be picked up that early in gestation, combined with the heterogeneity of these clinical conditions late in pregnanPublished online: April 19, 2013