The impact of antinuclear antibodies and complement levels in the prognosis of pregnant women within the antiphospholipid syndrome spectrum.

Introduction: To assess the prevalence and clinical impact of antinuclear antibodies (ANA) and low complement levels on fetal-maternal outcomes in pregnant women within the spectrum of obstetric antiphospholipid syndrome (APS). Methods: A total of 285 ever-pregnant women with APS-related obstetric morbidity were included. Among them, 85 fulfilled APS classification criteria, 139 were classified as non-criteria APS (NC-APS), and 61 as seronegative APS (SN-APS). Patients with other autoimmune diseases were excluded. Adverse pregnancy outcomes (APO) included early pregnancy loss, fetal death, preeclampsia, abruptio placentae, and preterm birth. Successful pregnancy was defined as the achievement of a live birth. ANA positivity and complement levels were analyzed in relation to obstetric outcomes and treatment prescription patterns. Results: Sixty patients (22.3%) were ANA positive. ANA positivity was associated with a lower number of pregnancies and live births, with the lowest ANA titers observed in the SN-APS group. Fifteen patients (6.3%) presented low complement levels. Hypocomplementemia was associated with a higher incidence of preeclampsia and early miscarriages, particularly among NC-APS patients. Additionally, all serological abnormalities were significantly associated with increased prescription of antimalarial therapy during pregnancy. Discussion: ANA positivity and hypocomplementemia were associated with poorer obstetric outcomes in women within the spectrum of obstetric APS. These serological abnormalities may identify a subgroup of patients with a higher-risk obstetric profile and greater need for intensified therapeutic management, including the use of antimalarial treatment during pregnancy.