Abstract-This study aimed to determine the performance of screening for preeclampsia (PE) by maternal medical history and mean arterial pressure (MAP) at 11 ϩ0 to 13 ϩ6 weeks. In 5590 women with singleton pregnancies attending for routine care at 11 ϩ0 to 13 ϩ6 week's gestation we recorded maternal variables and measured the MAP. We excluded 397 because they had missing outcome data or the pregnancies resulted in miscarriage or termination. In 104 patients there was subsequent development of PE, 97 developed gestational hypertension, 574 delivered small-for-gestational-age newborns, and 4418 were unaffected by PE, gestational hypertension, or small for gestational age. A multivariate Gaussian model was fitted to the distribution of log multiple of the median MAP in the PE and unaffected groups. Likelihood ratios for log multiple of the median MAP were computed and used together with maternal variables to produce patient-specific risks for each case. Detection rates and false-positive rates were calculated by taking the proportions with risks above a given risk threshold. In the unaffected group, log MAP was influenced by maternal age, ethnic origin, smoking, family and personal history of PE, and fetal crown-rump length. In the prediction of PE, significant contributions were provided by log multiple of the median MAP, ethnic origin, body mass index, and personal history of PE. The detection rate of PE by log multiple of the median MAP and maternal variables was 62.5% for a false-positive rate of 10%. Maternal variables, together with MAP, at 11 ϩ0 to 13 Key Words: first trimester Ⅲ mean arterial pressure Ⅲ pregnancy Ⅲ preeclampsia Ⅲ screening P reeclampsia (PE), which affects Ϸ2% of pregnancies, is a major cause of perinatal and maternal morbidity and mortality. 1-3 Attempts at prevention of PE by prophylactic interventions from midgestation have been largely unsuccessful. 4 -7 It is uncertain whether interventions starting from the first rather than the second trimester would prove to be more effective in the prevention of PE, but before this could be investigated, it is essential to develop a method of effective and early identification of the high-risk group.The likelihood of developing PE is increased by a number of factors in the maternal history, including Afro-Caribbean ethnicity, nulliparity, high body mass index (BMI), and previous or family history of PE. 8,9 However, screening by maternal history alone will detect only Ϸ30% of those who will develop PE, for a falsepositive rate (FPR) of 10%. 9 The diagnosis of PE is based on the demonstration of high blood pressure (BP) and significant proteinuria during the second half of pregnancy in previously normotensive women. Several second-trimester studies have reported on the use of BP measurement as a screening method for subsequent development of PE. These studies have reported contradictory results with FPR ranging from 7% to 52% and detection rates (DRs) ranging from 8% to 93% (Table 1). 10 -19 These differences are likely to be the consequence of the...
