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Jeltsje S Cnossen, Karlijn C Vollebregt, Nynke de Vrieze, Gerben ter Riet, Ben W J Mol, Arie Franx, Khalid S Khan, and Joris A M van der Post
Accuracy of mean arterial pressure and blood pressure measurements in predicting pre-eclampsia: systematic review and meta-analysis
BMJ 2008; 336: 1117-1120 [Abstract] [Full text]
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[Read Rapid Response] Absence of mid-pregnancy drop in prediction of preeclampsia: A myth?!
Wietske Hermes, Christianne J.M. de Groot and Kitty W.M. Bloemenkamp   (15 August 2008)

Absence of mid-pregnancy drop in prediction of preeclampsia: A myth?! 15 August 2008
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Wietske Hermes,
MD
Albinusdreef 2, 2300 RC, Leiden, The Netherlands,
Christianne J.M. de Groot and Kitty W.M. Bloemenkamp

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Re: Absence of mid-pregnancy drop in prediction of preeclampsia: A myth?!

Cnossen et al. reviewed the literature on the accuracy of blood pressure measurements during pregnancy to predict preeclampsia.(1) They conclude that if blood pressure is measured in the first or second trimester of pregnancy, the mean arterial pressure is a better predictor for preeclampsia compared to systolic blood pressure, diastolic blood pressure, or an increase of blood pressure.(1)

In daily clinic and literature the absence of a mid-pregnancy drop in blood pressure has been cited as a warning sign for the development of preeclampsia. However, to our knowledge this has never been studied.

In a case control study, we examined the effect of absence of a mid- pregnancy drop in blood pressure, the diastolic blood pressure at booking and the mean arterial pressure at booking on the risk of preeclampsia.

In absence of a clear and uniform definition in literature, mid- pregnancy drop in blood pressure in this study was defined as a decrease of at least 5 mmHg in diastolic blood pressure in the first half of pregnancy. Preeclampsia was defined according to the criteria of the ISSHP.

Nulliparous women, who had preeclampsia and delivered in a tertiary hospital in Leiden were included (N=80). Control subjects were matched for parity, age, duration of pregnancy and delivery date (N=87). Women with chronic hypertension were excluded. In 45% of the preeclampsia group and 40% of the control group a mid- pregnancy drop in blood pressure was absent (OR 0.8; 95% CI 0.4 – 1.5); positive likelihood ratio 0.92 and negative likelihood ratio 0.88. The odds ratio of developing preeclampsia for women with diastolic blood pressure at booking of greater than 70 mmHg was 3.1 (95% CI 1.6 - 5.6). The odds ratio of the mean arterial pressure at booking greater than 90 mmHg was 1.7 (95% CI 0.95 – 3.2). In conclusion, a mid-pregnancy drop in blood pressure, does not appear to be an accurate predictive test for preeclampsia in this case control study.

Reference 1. Cnossen JS, Vollebregt KC, de Vrieze N, ter Riet G, Mol BWJ, Franx A, Khan KS, van der Post JAM. Accuracy of mean arterial pressure and blood pressure measurements in predicting preeclampsia: systematic review and meta-amalysis. BMJ 2008; 336; 1117-1120

Competing interests: None declared