British researchers have developed an algorithm, which appears to be a far better predictor of gestational hypertension than the conventional approach of maternal history alone:
- Mean arterial pressure
- Uterine artery pulsatility index
Gestational hypertension can be detected by 11-13 weeks gestation and with only a 5% false positive rate with the algorithm, Dr. Leona C. Y. Poon and colleagues at King's College Hospital in London, report in the May issue of Hypertension.
The authors evaluated the outcomes of 7,797 singleton pregnancies. There were 136 pregnancies with gestational hypertension, 34 pregnancies with preeclampsia requiring delivery before 34 weeks (early preeclampsia) and 123 pregnancies with late preeclampsia.
Dr. Poon's team took maternal histories and measured mean arterial pressure, uterine artery pulsatility index and pregnancy-associated plasma protein-A in all of the pregnancies. Placental growth factor was measured in all pregnancies with hypertensive disorders and in 418 controls.
Early preeclampsia and late preeclampsia were associated with increases in mean arterial pressure and uterine artery pulsatility index and decreases in pregnancy-associated plasma protein-A and placental growth factor.
The investigators devised an algorithm with which they estimated that 93.1% of early preeclampsia, 35.7% of late preeclampsia and 18.3% of gestational hypertension could be detected with a 5% false-positive rate. One in 5 pregnancies classified as positive would develop pregnancy hypertension.
In an accompanying editorial, Drs. Richard J. Levine and Martin D. Lindheimer say that "Poon et al are to be congratulated for developing a predictive model with the likelihood ratios for positive and negative tests needed for a clinically useful approach to predict early preeclampsia."
However, "the approach is only applicable in developed nations, where the incidence of serious complications from preeclampsia has already been substantially reduced by the dictums of appropriate prenatal care." Even so, "their work opens the possibility of identifying women at high risk of early disease in time to modify care to minimize maternal and fetal complications."