Pregnancies in patients with systemic lupus erythematosus during 2000-2018 in Finland: a case-control study

The aim was to investigate, how pregnancies proceed in patients with systemic lupus erythematosus (SLE) compared to their individually matched population controls.

Adult incident SLE patients were identified from the register of new special reimbursement decisions for SLE drugs in 2000-2014. For each patient, 1-3 randomly selected controls from the Population Register Centre were matched. Data regarding pregnancies were obtained from the Finnish Medical Birth Register, Care Register and Register of Congenital Malformations until 2018. The study utilized data from the Drug Purchase Register and educational information from Statistic Finland.

A total of 163 deliveries for 103 mothers with SLE and 580 deliveries for 371 population controls were identified. The duration of pregnancies in SLE women was significantly shorter compared to controls (38.9 versus 39.6 weeks). There were more urgent Caesarean Sections. (15% versus 9%) and need for care at neonatal intensive care unit (NICU) (21% versus 11%) among deliveries in SLE mothers. No statistical difference was observed between SLE and control groups in the occurrence of preeclampsia or major congenital malformations. Gestational age was 2.5 weeks shorter when the mother experienced pre-eclampsia. Hydroxychloroquine was purchased by 30% of SLE mothers during pregnancy.

The course of pregnancies in Finnish SLE patients seems to be quite moderate compared to controls, and no new safety issues were detected. The low utilization of hydroxychloroquine indicates that the benefits of the drug to pregnancy and disease course are not optimally recognized by specialists treating SLE mothers.