Predicting adverse obstetric outcome after early pregnancy events and complications: a review

The aim was to evaluate the impact of early pregnancy events and complications as predictors of adverse obstetric outcome. We conducted a literature review on the impact of first trimester complications in previous and index pregnancies using Medline and Cochrane databases covering the period 1980-2008. Clinically relevant associations of adverse outcome in the subsequent pregnancy with an odds ratio (OR) > 2.0 after complications in a previous pregnancy are the risk of perinatal death after a single previous miscarriage, the risk of very preterm delivery (VPTD) after two or more miscarriages, the risk of placenta praevia, premature preterm rupture of membranes, VPTD and low birthweight (LBW) after recurrent miscarriage and the risk of VPTD after two or more termination of pregnancy. Clinically relevant associations of adverse obstetric outcome in the ongoing pregnancy with an OR > 2.0 after complications in the index pregnancy are the risk of LBW and very low birthweight (VLBW) after a threatened miscarriage, the risk of pregnancy-induced hypertension, pre-eclampsia, placental abruption, preterm delivery (PTD), small for gestational age and low 5-min Apgar score after detection of an intrauterine haematoma, the risk of VPTD and intrauterine growth restriction after a crown-rump length discrepancy, the risk of VPTD, LBW and VLBW after a vanishing twin phenomenon and the risk of PTD, LBW and low 5-min Apgar score in a pregnancy complicated by severe hyperemesis gravidarum. Data from our literature review indicate, by finding significant associations, that specific early pregnancy events and complications are predictors for subsequent adverse obstetric and perinatal outcome. Though, some of these associations are based on limited or small uncontrolled studies. Larger population-based controlled studies are needed to confirm these findings. Nevertheless, identification of these risks will improve obstetric care.