Hydroxychloroquine in Lupus Pregnancy and Risk of Preeclampsia

Systemic lupus erythematosus (SLE) disproportionately affects women during childbearing years, and hydroxychloroquine (HCQ) is the standard first-line treatment. Preeclampsia complicates up to one-third of pregnancies in lupus patients, although reports vary by parity and multifetal gestation. We investigated whether taking HCQ early in pregnancy may reduce the risk of preeclampsia.

We studied 1,068 live birth singleton pregnancies among 1,020 privately insured patients with SLE (2007-2016). HCQ treatment was defined as three months preconception through the first trimester, and prescription fills were a proxy for taking HCQ. Modified Poisson regression estimated risk ratios (RRs) and 95% confidence intervals (CIs), stratified by parity. Propensity scores accounted for confounders, and stratified analyses examined effect modification.

Approximately 15% of pregnant patients were diagnosed with preeclampsia. In 52% of pregnancies, patients had one or more HCQ fills. Pregnant patients exposed to HCQ had more comorbidities, SLE activity, and azathioprine treatment. We found no evidence of a statistical association between HCQ and preeclampsia among nulliparous (RR 1.26 [95% CI 0.82-1.93]) and multiparous pregnancies (RR 1.20 [95% CI 0.80-1.70]). Additional controls for confounding decreased the RRs toward the null (nulliparous pregnancy, propensity score-adjusted [PS-adj] RR 1.09 [95% CI 0.68-1.76]; multiparous pregnancy, PS-adj RR 1.01 [95% CI 0.66-1.53]).

Using a large insurance-based database, we did not observe a decreased risk of preeclampsia associated with HCQ treatment in pregnancy, although we cannot rule out residual and unmeasured confounding and misclassification. Further studies leveraging large population-based data and prospective collection could characterize how HCQ influences preeclampsia risk in pregnant patients with SLE and among persons at greater risk of hypertensive disorders of pregnancy.