Purpose We sought to determine whether the type of SLE activity, particularly lupus nephritis compared to non-renal SLE activity, determined the level of pregnancy risk.

Methods All pregnancies in women with SLE enrolled <30 weeks gestation from 2 prospective registries (2007–2022) were included. Pregnancies with twins or a loss <12 weeks were excluded. SLE activity was assessed using the physician’s global assessment (PGA; 0 to 3) at each clinic visit. Active lupus nephritis was adjudicated by a roundtable of 6 physicians. Pregnancies outcomes were compared between 3 groups:

• Inactive SLE: PGA <1.5 throughout pregnancy, no renal activity

• Active non-renal SLE: PGA at least 1.5 in pregnancy, no renal activity

• Active LN: active nephritis during pregnancy

Results Of 115 pregnancies, 70 (61%) had inactive SLE throughout pregnancy, 30 (26%) had active non-renal SLE, and 15 (13%) had active lupus nephritis during pregnancy. Women with inactive SLE were older and more likely to be White, have a college degree and private health insurance, and live with a partner (table 1). Hydroxychloroquine and aspirin were frequently prescribed to all groups. Azathioprine was more frequently prescribed for active SLE, especially active nephritis. The majority of patients with active SLE received prednisone, with or without nephritis, though at higher doses for active nephritis. Positive dsDNA and/or low complement was similarly high among women with active SLE.

The frequency of poor pregnancy outcomes, including preterm birth, preeclampsia, and low APGAR score were significantly higher among women with active nephritis (figure 1). Active non-renal SLE did not increase adverse pregnancy outcomes. Pregnancies with active nephritis delivered earlier than other pregnancies (33.2wks active nephritis, 36.5wks active non-renal, and 37.2wks inactive SLE, p<0.0001).

Conclusions Active lupus nephritis, but not active non-renal SLE, was associated with dramatically higher rates of adverse outcomes than inactive SLE. Differences in social determinants of health between groups could play a role both in the presence of active nephritis and worsened adverse pregnancy outcomes. This data suggests that active lupus nephritis in pregnancy is an important determinant of pregnancy outcomes and focuses our attention on the unmet medical need of these patients.

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Abstract 602 Figure 1

Pregnancy Outcomes by Active SLE, with and without Active Nephritis