A relationship between SLE and pregnancy complications has been previously established. The purpose of the present study was to evaluate the association of SLE with SMM according to the WHO standardized definitions and criteria [9], as well as compare sociodemographic, obstetric, perinatal characteristics, and maternal morbidity features in this cohort.
The elevated incidence rate of MNM in this study (112.9 cases per 1,000 live births) demonstrates that SLE has as a severe impact on pregnancy. The range of MNM incidence rates (per 1,000 live births) in the general population according to the WHO criteria is 9.35 to 13.5 in Brazil and Latin American countries [10-15], 5.9 in the United States of America [16], and 21.5 in Rwanda [17]. Additionally, the PLTC and MNM groups revealed a higher frequency of complications, such as prematurity, stillbirth, miscarriage, neonatal death, low birth weight, and a longer period of hospitalization. We identified a high association between SMM and maternal and fetal complications, including low birth weight, neonatal death, fetal loss, and miscarriage, correlating with previous reports [7, 18-23]. Prematurity was one of the most significant complications, with the majority of pregnancies in the MNM group delivering earlier than 27 weeks (71.5%), with statistically significant increased risk of preterm delivery in both MNM and PLTC groups.
Patients in both SMM groups had a statistically significant longer hospitalization period, with the main criteria "Prolonged hospital stay (> 7 days)". Therefore, we emphasize the importance of applying strategies that improve the health care of these patients. Better prenatal follow-up may lower the risk of complications, likely decreasing long-term hospitalization, and reducing social and economic costs, which benefit public national health systems. As previously mentioned, among the 70 patients with SMM, 56 presented with PLTC and 14 with MNM. Thus, it could be argued that theoretically 80% of the PLTC cases were identified and reversed before evolving to maternal near miss cases. This analysis directly reflects service assistance quality and can be useful in audits as well as subsequent implementations and improvements in health care [24].
The association of renal impairment and severe maternal morbidity among the patients indicated that the presence of lupus nephritis during gestation is a relevant factor for developing complications. Cases with positive antiphospholipid antibodies or anti-phospholipid antibody syndrome associated with SLE also had a higher risk of developing PLTC. Several studies have indicated the presence of previous lupus nephritis, chronic hypertension, and positive antiphospholipid antibodies, such as anticardiolipin antibody and lupus anticoagulant, to be predictors of poor obstetric and neonatal outcomes in patients with SLE [7,8,18-20,25-27].
There were two unexpected results in this study, one was the relation between hematological impairment and a higher percentage of MNM compared to control group. The other one was the association of cutaneous criteria (malar rash, discoid rash and photosensitivity) with a lower percentage of cases with SMM. Such relationships have not been found in previous studies regarding lupus during pregnancy. In order to understand the first finding, the 10 MNM cases with hematological criteria were analyzed individually and it was found that in 7 of them there was also nephritis, with the presence of laboratory and management criteria "Creatinine ≥ 3,5 mg / dl " and "Dialysis for acute renal failure ", respectively. Therefore, nephritis was believed to be a bias factor for this result. No bias factor was identified for the second unexpected finding; therefore, cutaneous criteria in SLE patients might be considered a weak sign for SMM and poor obstetric outcomes. However, new studies should be performed to define this relationship more clearly.
This retrospective study has some limitations. As this study was based on existing medical records, some data was missing. Additionally, although we selected a 10-year period for this study to provide an adequate number of patients, in the future, a larger sample size and the collection of prospective data may provide more representative results.