Early hydroxychloroquine exposure cuts pre-eclampsia risk in pregnant women with lupus

For women with systemic lupus erythematosus (SLE), hydroxychloroquine exposure in early pregnancy is linked to a lower risk of pre-eclampsia, a study has shown.

Researchers looked at 959 singleton pregnancies (42 percent nulliparous) from 685 women (mean age 32 years) with prevalent SLE in Sweden. Hydroxychloroquine exposure was defined as at least two prescription fills from 3 months prepregnancy until the end of the first trimester.

The primary outcomes were pre-eclampsia (diagnosed from 20 weeks of gestation to 6 weeks postpartum) and preterm delivery (delivery before 37 weeks of gestation). Inverse probability of treatment weighting and modified Poisson models were used in the analyses.

Among nulliparous pregnancies, 43 percent were hydroxychloroquine-exposed and 57 percent were unexposed. Among parous pregnancies, 40 percent were hydroxychloroquine-exposed and 60 percent were unexposed.

Pre-eclampsia occurred in 11 percent of hydroxychloroquine-exposed pregnancies and 13 percent of unexposed pregnancies in the nulliparous group, and in 5 percent and 6 percent, respectively, in the parous group. Preterm delivery occurred in 19 percent of hydroxychloroquine-exposed pregnancies and 15 percent of unexposed pregnancies in the nulliparous group, and in 12 percent each in the parous group.

Hydroxychloroquine exposure was associated with a reduced risk of pre-eclampsia in SLE pregnancies (adjusted risk ratio [aRR], 0.49, 95 percent confidence interval [CI], 0.31–0.79) overall, in the nulliparous group (aRR, 0.59, 95 percent CI, 0.33–1.08), and in the parous group (aRR, 0.44, 95 percent CI, 0.22–0.89).

Associations between hydroxychloroquine exposure and preterm delivery were unclear. Similar results were obtained in subgroups defined by antiphospholipid syndrome, renal diseases, and hypertension status.