Preeclampsia Can Be Predicted by 2 Variables

Two second-trimester variables can predict the development of pre eclampsia in the third trimester, according to a study that earned the Out standing Research Paper Award at the Association of Women’s Health, Obstet ric and Neonatal Nurses annual meeting.

“It seems that something earlier in pregnancy must be happening before blood pressure becomes that magic number that nurses look for—140/90 mm Hg,” said Rita J. Nutt, DNP, RN, of Salisbury University, MD.

To explore patient characteristics as predictors of preeclampsia, Dr Nutt used a retrospective case-control model to compare second-trimester blood pressure (BP) rates of women who developed preeclampsia (n = 36) with those of women who remained nor mo tensive (n = 108) in a single obstetrical practice within a tertiary care medical center.

Dr Nutt looked at the normal physiologic 10-mm Hg drop in diastolic BP that usually occurs in the second trimester. Her hypothesis was that a failure to experience this anticipated drop might increase the likelihood of developing preeclampsia. The patients’ second- trimester BP measurements were averaged, and this number was compared with the initial prenatal visit reading to ascertain whether the physiologic drop occurred.

“We found that women who did not experience this BP drop were almost 9 times more likely to develop preeclampsia,” Dr Nutt reported. “We also found that weight gain in excess of the guidelines based on body mass index [BMI] was associated with nearly a 3-fold increased risk.”

The adjusted odds ratios for preeclampsia were 8.8 for the lack of a diastolic BP dip and 2.8 for weight gain above the recommendation. For overweight women, the risk was increased 5- fold. Initial diastolic pressure and BMI were not associated with the development of preeclampsia.

The model correctly predicted 78.5% of preeclampsia cases, she said. The study showed that 36.8% of the women who did not have the anticipated BP drop progressed to preeclampsia, unlike the 63.2% of women who remained normotensive. In other words, 32 of the 36 women who had preeclampsia did not have this drop in BP.

“This study showed that changes in blood pressure seen in preeclamptic patients predate the time-frame—late pregnancy—when preeclampsia is historically diagnosed,” she said.

Practical Implications
Dr Nutt offered the following recommendations to nurses:

• Consider BP in the context of the entire patient profile
• Use only licensed nursing staff to obtain measurements
• Record and evaluate BP carefully
• Track BP numerically and graphically in a format that takes into account the gestational period
• Counsel women regarding weight gain, with special consideration paid to overweight and obese women.

“Some risk factors, like race, first pregnancy, and age, we cannot control,” Dr Nutt said. “But the findings indicate that maybe we can lower the risk by controlling weight gain.”