Nighttime aspirin, BP test target preeclampsia. (Predicting who will Develop the Disorder).

New studies support two innovative strategies in the war against preeclampsia--the tolerance-hyperbaric test and low-dose aspirin taken at night.

The tolerance-hyperbaric test (THT) can be used as early as the first trimester to identify up to 93% of pregnant women who will develop blood pressure complications months before they have symptoms that standard tests can detect, said Ramon C. Hermida, Ph.D., of the University of Vigo (Spain).

A second study, also conducted by Dr. Hermida and his associates, included 341 women at high risk for preeclampsia. In that study, only 1.7% of those who took low-dose aspirin at bedtime later developed preeclampsia, compared with 14% of those women who took a placebo--a significant difference, he said.

In the first study, which included 403 women, the THT was used to compare a pregnant patient's blood pressure changes over a 48-hour period with the expected variability of blood pressure due to natural circadian rhythms. Patients whose readings were consistently outside the expected range were flagged.

Study participants wore a portable blood pressure cuff and monitor to record the readings.

The investigators analyzed data from 2,430 blood pressure series sampled by ambulatory blood pressure monitoring for 48 hours once every 4 weeks from the first obstetric visit until delivery.

A total of 168 women ultimately developed gestational hypertension or preeclampsia, and 235 had uncomplicated pregnancies.