Predictors of Maternal Morbidity Among Participants Enrolled in the Sickle Cell Disease Implementation Consortium Registry

Introduction

Pregnancy in sickle cell disease (SCD) is associated with an exacerbation of SCD-related complications and an increased risk of maternal complications. The increased risk is partly due to physiologic adaptations in pregnancy, which include increased metabolic demands and a hypercoagulable state. The maternal death rate for SCD is 629 per 100,000 deliveries, compared to 12 per 100,000 deliveries in black women and 6 per 100,000 deliveries in the general population (Raider et al., 2016). Studies on maternal and perinatal outcomes of patients with SCD present inconsistent and conflicting results. Some studies have reported an increase in maternal complications such as pre-eclampsia, acute chest syndrome and thromboembolic events, while other studies have reported no significant risk in adverse maternal outcomes. The inconsistent findings reported in prior studies may be attributed to small sample sizes and single-centered sites. Our study aims to determine the prevalence and predictors of maternal morbidity among participants enrolled in the SCD Implementation Consortium (SCDIC) registry, which is the largest, most geographically diverse SCD participant sample in the United States.

Methods

This cross-sectional study included women enrolled in the SCDIC registry who had at least one pregnancy event. The SCDIC is composed of eight academic SCD centers across the United States and one data-coordinating center. Participants were enrolled in the SCDIC registry if they were 18 to 45 years of age and had a confirmed diagnosis of SCD. Enrolled participants completed a series of surveys that collected sociodemographic information, SCD and pregnancy history and data abstractions of participants' medical records was completed. Medical complications queried during pregnancy included: vaso-occlusive episodes, acute chest syndrome, blood transfusion requirement, preeclampsia, maternal diabetes and deep venous thrombosis. Descriptive analysis of sociodemographic, clinical and maternal characteristics was conducted. Bivariate analysis was performed using Chi-Square test, Mann-Whitney U test, t-test, and logistic regressions, as appropriate. A p-value of ≤ 0.05 was considered statistically significant for all analysis.

Results

The study sample included 743 women who had at least one pregnancy event, and a total of 1066 live births. Almost all women (96.3%) were African American, with a median age of 21 years (inter-quartile range of 19 to 23 years) at first birth. The majority had Hb SS SCD genotype (69.5%; 513 of the 738 with SCD genotype data). Of all reported pregnancies, participants did not use hydroxyurea during conception (78%), and pregnancy (84.5%). Only 2.7 % of the women reported using fertility drugs or assisted reproductive procedures. Seventy five percent of the pregnancies that ended in live births had maternal complications. The leading complications were vaso-occlusive episodes (61.2%), pregnancy requiring blood transfusion(s) (33.2%), preeclampsia (15.4%), deep venous thrombosis (5.6%) and acute chest syndrome (7.7%). When the pregnancies were stratified by SCD genotype, women with Hb SS had a higher occurrence of acute chest syndrome (63.4% vs. 26.7%), transfusion requirement (70.8% vs. 21%) and preeclampsia (66.7% vs 22.4%). In the univariate logistic regressions, multiparous women, with a history of adverse maternal outcomes in a previous pregnancy, had higher odds of vaso-occlusive episodes (OR: 3.42; 95% CI: 2.42-4.94) acute chest syndrome (OR:4.99; 95% CI:2.56- 9.48), transfusion requirement (OR:3.86; 95% CI:2.64- 5.69), and pre-eclampsia (OR:3.36; 95% CI:2.05-5.45).

Conclusion

In this large multicenter registry, we found pregnant women with SCD have significant maternal complications. Early antenatal care by healthcare providers knowledgeable about risk factors for adverse maternal outcomes in SCD is essential improve maternal and fetal outcomes and reduce the maternal death rate for SCD.