There is consistent evidence that many of the pregnancy complications that occur late in the second and third trimester can be predicted from an integrated 11-13 weeks visit, where a maternal and fetal assessment are comprehensively performed. The traditional aims of the 11-13 weeks visit have been: establishing fetal viability, chorionicity and dating of the pregnancy, and performing the combined screening test for common chromosomal abnormalities. Recent studies have shown that the first trimester provides important information that may help to predict pregnancy complications, such as preeclampsia and fetal growth restriction, stillbirth, preterm birth, gestational diabetes mellitus and placenta accreta spectrum disorder. The aim of this manuscript is to review the methods available to identify pregnancies at risk for adverse outcomes after screening at 11-13 weeks. Effective screening in the first trimester improves pregnancy outcomes by allowing specific interventions such as administering aspirin and directing patients to specialist clinics for regular monitoring.
Keywords: 11–13 weeks; chromosomal abnormalities; fetal growth restriction; first trimester; gestational diabetes; placenta accreta spectrum; preeclampsia; pregnancy outcomes; preterm birth; small for gestational age; structural defects.