Risk factors for pre-eclampsia at antenatal booking: systematic review of controlled studies

Objective To determine the risk of pre-eclampsia associated with factors that may be present at antenatal booking. Design Systematic review of controlled studies published 1966-2002. Data synthesis Unadjusted relative risks were calculated from published data. Results Controlled cohort studies showed that the risk of pre-eclampsia is increased in women with a previous history of pre-eclampsia (relative risk 7.19, 95% confidence interval 5.85 to 8.83) and in those with antiphospholipid antibodies (9.72,4.34 to 21.75), pre-existing diabetes (3.56, 2.54 to 4.99), multiple (twin) pregnancy (2.93, 2.04 to 4.2 1), nulliparity (2.9 1, 1.28 to 6.61), family history (2.90, 1.70 to 4.93), raised blood pressure (diastolic >= 80 min Hg) at booking (1.38, 1.01 to 1.87), raised body mass index before pregnancy (2.47, 1.66 to 3.67) or at booking (1.55, 1.28 to 1.88), or maternal age >= 40 (1.96, 1.34 to 2.87) for multiparous women. Individual studies show that risk is also increased with an interval of 10 years or more since a previous pregnancy, autoimmune disease, renal disease, and chronic hypertension. Conclusions These factors and the underlying evidence base can be used to assess risk at booking so that a suitable surveillance routine to detect pre-eclampsia can be planned for the rest of the pregnancy.