Correspondence

Prevention of Preeclampsia with Low-Dose Aspirin

N Engl J Med 1994; 330:794-795March 17, 1994

Article

To the Editor:

In the report by Sibai et al. (Oct. 21 issue)1 on the use of low-dose aspirin to prevent preeclampsia, the overall perinatal mortality was similar in the aspirin and placebo groups (aspirin: 22 deaths among a total of 1545 fetuses, or 14.2 deaths per 1000 live births; placebo: 14 deaths among 1551 fetuses, or 9.0 deaths per 1000 live births), but the difference in the number of fetal deaths after 20 weeks' gestation was almost significant by chi-square analysis (17 deaths among 1570 fetuses vs. 7 among 1565, respectively; P = 0.06). As Zuspan and Samuels point out in their editorial,2 the differences between the aspirin and placebo groups might have been even larger if compliance had been perfect. Were the fetal deaths clustered in any of the subgroups -- for example, among the women with higher initial blood pressure, who were more likely to benefit from aspirin with respect to preeclampsia?

We realize that women who seek prenatal care may be less likely than others to use drugs during pregnancy. However, since cocaine use during pregnancy has been associated with abruptio placentae,3 information on differences in drug use between the two study groups may be important.

Fernando R. Moya, M.D.
Southwestern Medical Center, Dallas, TX 75235-9063

Alfredo Germain, M.D.
Catholic University of Chile, Santiago, Chile

3 References

1. 1

   Sibai BM, Caritis SN, Thom E, et al. Prevention of preeclampsia with low-dose aspirin in healthy, nulliparous pregnant women. N Engl J Med 1993;329:1213-1218
   Full Text | Web of Science | Medline

2. 2

   Zuspan FP, Samuels P. Preventing preeclampsia. N Engl J Med 1993;329:1265-1266
   Full Text | Web of Science | Medline

3. 3

   Handler A, Kistin N, Davis F, Ferre C. Cocaine use during pregnancy: perinatal outcomes. Am J Epidemiol 1991;133:818-825
   Web of Science | Medline

Author/Editor Response

Dr. Sibai replies:

To the Editor: Drs. Moya and Germain suggest that the difference in fetal deaths between the aspirin and placebo groups is almost significant by chi-square analysis. However, the numbers used for this analysis are incorrect, since the calculations should be based on pregnancies continuing beyond 20 weeks' gestation (1497 in the aspirin group and 1512 in the placebo group). Among the 16 women with fetal loss in the aspirin group, only 4 had a systolic blood pressure of 120 mm Hg or higher at the time of randomization, whereas in the placebo group, none of the 7 mothers with fetal loss had a systolic blood pressure of 120 mm Hg or higher. Overall, four of the women with fetal loss (17 percent) had a systolic blood pressure of 120 mm Hg or higher at the time of randomization -- an incidence that is similar to that among the women who did not have fetal loss.

Cocaine use during pregnancy was a criterion for exclusion from this study. Thus, none of the women enrolled had a history of cocaine use. In one center where urinary drug screening was performed routinely, five women had abruptio placentae, and none had a positive urine test for cocaine.

Baha M. Sibai, M.D.
University of Tennessee, Memphis, Memphis, TN 38103