Women with sickle cell trait are at increased risk for preeclampsia

Our purpose was to determine the rate of preeclampsia in women who are positive for sickle cell trait.

All African-American women were tested for sickle cell trait with the "sickledex" screen at the fist prenatal visit and prospectively enrolled in this study from March 1994 to June 1995. "Sickledex" screens were confirmed with hemoglobin electrophoresis. Demographic data were collected at the time of enrollment. Outcome data, including preeclampsia (as defined by The American College of Obstetricians and Gynecologists criteria), gestational age at delivery, birth weight, and postpartum endometritis were collected immediately post partum. Assuming a 10% rate of positive sickle cell trait, 1100 patients were required to demonstrate a doubling in the rate of preeclampsia with 80% power and p < 0.05. The Student t test, the Mann-Whitney U test, chi 2 analysis, and Fisher's exact tests were used for statistical analysis.

Of 1584 women enrolled in the study, 162 were positive for sickle cell trait. Sickle cell trait-positive women were older than the sickle cell trait-negative women (24.4 +/- 4.6 vs 23.0 +/- 4.4 years, p < 0.001), but there was no significant difference in parity. The rate of preeclampsia was significantly increased in sickle cell-positive women (24.7% vs 10.3%, p < 0.0001). There was no significant difference in the rate of chronic hypertension, diabetes, or smoking. Parous sickle cell-positive women more frequently gave a history of preeclampsia in a previous pregnancy (21.4% vs 9.3%, p < 0.0001). There was a statistically significant decrease in gestational age at delivery and birth weight in sickle cell trait-positive women (36.7 +/- 2.7 vs 37.7 +/- 3.0 weeks, p < 0.0001; and 3082 +/- 591 vs 3369 +/- 573 gm, p < 0.0001). The rate of postpartum endometritis was significantly increased in the women positive for sickle cell trait (12.3% vs 5.1%, p < 0.001), although both groups had a similar cesarean section rate (14.8% vs 12.6%, not significant).

This is the first prospective study to demonstrate that sickle cell trait-positive women are at significantly higher risk for development of perinatal complications that have traditionally been associated with sickle disease.