Background Women with Systemic Lupus Erythematosus (SLE) face a higher risk of pre-eclampsia, especially those with additional risk factors. Low dose aspirin (LDA) is known to protect against pre-eclampsia in non-autoimmune patients. Consequently, the EULAR recommends starting LDA in those women at risk preconceptionally or latest until gestational week 16. We sought to examine the use of LDA in a real-world cohort in relation to different risk factors and the provision of preconception counselling.

Methods Pregnancies of women with SLE from an outpatient pregnancy clinic were evaluated before and throughout pregnancy. Clinical characteristics including pre-eclampsia risk factors, disease activity (SLEDAI) and medication use were analysed. Association of Aspirin use (latest from week 16 on) with different risk factors or preconception counselling was analysed using χ² tests.

Results We enrolled 201 pregnancies in 136 women. 57.8% of pregnancies showed a high-risk profile for pre-eclampsia (history of pre-eclampsia, multifetal gestation, chronic hypertension, lupus nephritis or aPL), another 26.6% had at least one moderate risk factor (nulliparous, body mass index>30 or age>35). LDA was administered in 43.3% of pregnancies. LDA use was significantly higher in those with a high-risk profile (63.5% vs. 16.7%) [OR 8.59 (95%-CI: 4.19–18.62), p<0.001], but not in those with a moderate-risk profile. Still, 36.5% of those at high risk and 83% of those at moderate risk did not receive Aspirin. In a descending order, aPL, multifetal gestation, lupus nephritis and nulliparity were associated with a higher LDA use, whereas the other risk factors were not.

Preconception counselling significantly increased Aspirin administration [OR 2.36 (95%-CI: 1.23–4.63), p<0.01], especially in those at high risk [OR 4.12 (95%-CI 1.72–10.16), p<0.001]. Overall, LDA use increased from 1995 to 2019 (χ² test for trend in proportions, p<0.001).

Conclusions We found a high prevalence of pre-eclampsia risk factors and infrequent use of aspirin in pregnant SLE patients. Preconception counselling increases the LDA use and thereby can improve pregnancy outcomes.