|NATIONAL INSTITUTES OF HEALTH
||National Heart, Lung, and Blood Institute|
|FOR IMMEDIATE RELEASE
Tuesday, October 24, 2000
NHLBI Communications Office
The report updates a recommendation on measuring diastolic blood pressure during pregnancy, suggesting that clinicians use K5 (disappearance) of the Korotkoff sound over K4 (muffling). Furthermore, gestational hypertension should be determined on the basis of at least two readings.
The causes of gestational hypertension and preeclampsia remain unknown, and standard screening tests or markers for preeclampsia remain somewhat elusive. However, the report identifies several indicators that point to the possibility of preeclampsia in women without chronic hypertension. These include elevated blood pressure and proteinuria occurring for the first time during pregnancy (after 20 weeks gestation) and rising levels of serum creatinine, uric acid, and transaminase levels.
In contrast to earlier guidelines, edema is no longer recognized as a diagnostic criterion for preeclampsia because it appears in too many normal pregnant women to be discriminant for this condition. In addition, the use of blood pressure increases of 30 mg Hg systolic or 15 mm Hg diastolic is no longer recommended.
Women with pre-existing (chronic) or early hypertension are at increased risk of preeclampsia, notes the report, and the prognosis for mother and fetus is worse than in cases in which hypertension first develops during pregnancy. Nearly one in four hypertensive women will develop preeclampsia during pregnancy, typically during midpregnancy. Those who have proteinuria early in their pregnancy are at increased risk for fetal loss and other complications independent of preeclampsia.
Signs of preeclampsia in these women include onset of proteinuria and a sudden increase in blood pressure if hypertension was previously well controlled. However, clinicians may have difficulty distinguishing between changes in blood pressure and early signs of preeclampsia.
"Detecting preeclampsia in women with chronic hypertension can be particularly challenging," notes Dr. Ray Gifford, Jr., of the Cleveland Clinic Foundation, who chaired the NHBPEP Working Group. "Because the consequences of missing a diagnosis of preeclampsia are dire, we encourage clinicians to overdiagnose if necessary."
According to the report, most women with chronic hypertension prior to pregnancy have Stage 1 or 2 hypertension (systolic blood pressure of 140 to 179 mm Hg or diastolic blood pressure of 90 to 109 mm Hg). Whenever possible, they should be evaluated before pregnancy to assess the severity of their hypertension and possible organ damage, and counseled as appropriate. Lifestyle changes regarding physical activity, weight loss, and sodium restriction should also be addressed.
Many patients with chronic hypertension may be able to control their blood pressure without medications or with less medication than used prior to gestation. The report suggests that, if needed, however, most antihypertensive medications – except angiotensin-converting enzyme inhibitors and angiotensin II receptor agonists –can be used safely during pregnancy.
Management of preeclampsia is based first on preventing maternal complications, and second on encouraging growth and maturation of the fetus and allowing the cervix to prepare for delivery -- the only definitive treatment of the condition. The Working Group Report identifies key indications for delivery in preeclampsia, such as gestational age (equal to or greater than 38 weeks) and low platelet count.
Hypertension and signs of organ dysfunction associated with preeclampsia typically disappear within six weeks of delivery. However, women with early-onset preeclampsia or preeclampsia in more than one pregnancy are more likely to develop hypertension later in life.
The "2000 Working Group Report on High Blood Pressure in Pregnancy" was published as a supplement in the July 2000 issue of The American Journal of Obstetrics and Gynecology.
The report is also on the NHLBI Web site as a PDF file, and can be ordered through the NHLBI Information Center at NHLBIinfo@rover.nhlbi.nih.gov or (301) 592-8573.
NHLBI press releases, scientific resources, and other materials are online at www.nhlbi.nih.gov.