Severe Maternal Morbidity and near Miss-Events in Women with Heart Disease: Insights from a Cohort Study

<b>Background/Objectives:</b> The maternal mortality ratio is one of the global health indicators, and cardiopathies are the leading indirect causes of maternal deaths. Proper management of pregnant women with heart disease is crucial, as the severity of these conditions can lead to complications during the perinatal period. This study aimed to evaluate the rate of severe maternal morbidity and associated factors in pregnant women with heart disease. <b>Methods:</b> A retrospective cohort study was conducted at a referral hospital in São Paulo from 2008 to 2017, including pregnant women with heart disease who underwent procedures in the obstetric center (<i>n</i> = 345). Sociodemographic, obstetric, and pre-existing conditions were analyzed, along with life-threatening conditions, near-miss events, and maternal deaths. Heart diseases were classified according to the World Health Organization (WHO) guidelines, and health indicators were calculated using WHO-recommended formulas. The Chi-square test or Likelihood Ratio test (<i>p</i> < 0.05) was used to compare severe maternal morbidity among women with heart disease. <b>Results:</b> The mean age of participants was 29.1 ± 7.29 years; most were white (58.8%), had completed high school (37.9%), and were married (71.6%). The most frequent pre-existing conditions were hypertension (9.6%) and diabetes mellitus (9.3%). The mean gestational age at admission/delivery was 37 weeks. According to the WHO classification, most women were classified as "II/III" (31.6%). Life-threatening conditions included hemorrhagic complications (13.9%), hypertensive complications (5.8%), clinical complications (19.7%), and severe management conditions (31.6%). Near-miss events occurred in 6.4% of patients, with clinical criteria in 2.9%, laboratory criteria in 4.3%, and management criteria in 3.5%. The cesarean section rate was 51%. Patients classified as WHO III and IV presented more severe management conditions (<i>p</i> < 0.0001), and those in WHO IV had a higher occurrence of near-miss events (<i>p</i> = 0.0001). Maternal mortality was 0.9% (<i>n</i> = 3). <b>Conclusions:</b> The incidence of severe maternal morbidity was 25 cases (22 near-miss events + 3 maternal deaths), equivalent to 2.86 per 1000 live births, and was significantly associated with WHO classifications III and IV.