Current issues of ACP Journal Club are published in Annals of Internal Medicine


Prognosis

Preeclampsia and baseline proteinuria in women with chronic hypertension were associated with adverse neonatal outcomes

ACP J Club. 1999 Mar-April;130:47. doi:10.7326/ACPJC-1999-130-2-047


Source Citation

Sibai BM, Lindheimer M, Hauth J, et al., for the National Institute of Child Health and Human Development Network of Maternal-Fetal Medicine Units. Risk factors for preeclampsia, abruptio placentae, and adverse neonatal outcomes among women with chronic hypertension. N Engl J Med. 1998 Sep 3;339:667-71.


Abstract

Question

In pregnant women with chronic hypertension, what are the risk factors for preeclampsia and adverse neonatal outcomes?

Design

Inception cohort followed from 20-week mean gestation to delivery.

Setting

Clinical centers in the United States.

Patients

774 women (55% ≤ 30 y of age, 18% primigravida) who had chronic hypertension and singleton pregnancies and were enrolled in a randomized controlled trial that compared low-dose aspirin with placebo for the prevention of preeclampsia.

Assessment of prognostic factors

Age, race, antihypertensive drug treatment, baseline proteinuria, preeclampsia, duration of hypertension, and diastolic blood pressure.

Main outcome measures

Preeclampsia, abruptio placentae, gestational age, preterm delivery (<37 wk of gestation), birthweight, admission to a neonatal intensive care unit (NICU), and neonatal complications.

Main results

25% of women had preeclampsia, and no difference existed between the low-dose aspirin and placebo groups. Risk factors for the development of preeclampsia were previous preeclampsia (P = 0.02), hypertension for ≥ 4 years (P = 0.007), and diastolic blood pressure between 100 and 110 mm Hg (P = 0.01). Women with preeclampsia were more likely to have abruption than were those without preeclampsia (3% vs 1%, P = 0.04). In multivariate analyses, preeclampsia (after adjustment for baseline proteinuria levels) and proteinuria (after adjustment for preeclampsia at delivery) were each associated with adverse neonatal outcomes (Table).

Conclusions

In pregnant women with chronic hypertension, proteinuria at baseline and preeclampsia during pregnancy were associated with adverse neonatal outcomes. Previous preeclampsia, hypertension for ≥ 4 years, and diastolic blood pressure ≥ 100 mm Hg were risk factors for preeclampsia.

Source of funding: National Institute of Child Health and Human Development.

For correspondence: Dr. B.M. Sibai, Department of Obstetrics, University of Tennessee, Memphis, 853 Jefferson Avenue, Suite E102, Memphis, TN 38103, USA. FAX 901-448-4701.


Table. Associations between risk factors (preeclampsia and baseline proteinuria) and adverse neonatal outcomes in women with chronic hypertension*

Outcomes at delivery Preeclampsia Baseline proteinuria
Adjusted OR† (95% CI) Adjusted OR† (CI)
Delivery < 37 wk 3.9 (2.7 to 5.4) 2.7 (1.6 to 4.3)
Delivery < 35 wk 4.1 (2.7 to 6.0) 3.1 (1.8 to 5.3)
Low birthweight 2.8 (1.6 to 5.0)
Admission to NICU 2.9 (2.0 to 4.2) 3.1 (1.9 to 5.2)
Intraventricular hemorrhage 4.5 (1.5 to 14.2) 3.9 (1.3 to 11.6)
Perinatal death 2.3 (1.1 to 4.8)

*OR = odds ratio; NICU = neonatal intensive care unit. Other abbreviations defined in Glossary.
†OR adjusted for baseline proteinuria level.
‡OR adjusted for preeclampsia at delivery.
§Not significant.


Commentary

The study by Sibai and colleagues originates from the reanalysis of data in a randomized controlled trial that compared aspirin with placebo for preventing preeclampsia (1). This evidence would have been stronger if all patients had had 24-hour urine collections, all infants had had cranial ultrasonography, and the clinical consequences of abruptio placentae were documented more clearly. In addition, there may be lead-time bias because patients were entered at up to 26 weeks of gestation.

Blood pressure measurement and urine testing for protein are standard in initial and subsequent prenatal visits. Despite the criticisms above, the importance of these tests is evident from this study. Pregnant women with chronic hypertension have a 4% perinatal mortality risk compared with the usual 1% perinatal mortality rate, a 12% delivery rate before 35 weeks, and a 20% to 25% risk for superimposed preeclampsia even without risk factors. Such women are best cared for by persons familiar with this combination. The recognition of increased blood pressure at the first visit should be confirmed and treated appropriately because this is likely to improve fetal outcomes (2). Because the presence of proteinuria further increases perinatal morbidity, the importance of the caregiver cannot be overemphasized.

The authors highlight the importance of counseling women with hypertension before conception about the adverse effects of proteinuria. I tend to be encouraging with these patients because 75% will not get superimposed preeclampsia, and although their children are likely to be small for gestational age, to be born early, and to spend some time in an NICU, the overall probability of survival is > 90%, which is unchanged from the patients without proteinuria.

Robert Burrows, MD
Monash UniversityMelbourne, Victoria, Australia


References

1. Caritis S, Sibai B, Hauth J, et al. Low-dose aspirin to prevent preeclampsia in women at high risk. National Institute for Child Health and Human Development Network of Maternal-Fetal Medicine Units. N Engl J Med. 1998;338:701-5.

2. Rey E, LeLorier J, Burgess E, Lange IR, Leduc L. Report of the Canadian Hypertension Society Consensus Conference: 3. Pharmacologic treatment of hypertensive disorders in pregnancy. CMAJ. 1997;157:1245-54.