Hypertensive disorders of pregnancy (HDP), referred to as gestational hypertension and preeclampsia [1], [2], [3] in this paper are common complications that affects up to 10 % of pregnancies in the United States (US) [4], [5], [6], [7]. HDP remain one of the leading causes of maternal morbidity and mortality [8]. Negative effects of HDP often persist postpartum and are associated with an increased lifetime risk of developing Type 2 Diabetes Mellitus (T2DM), hypercholesterolemia, and chronic hypertension [9], [10]. Our group recently reviewed the rates of new diagnosis of chronic hypertension following HDP at one year postpartum [11]. Nearly half (45 %) of the patients with HDP had chronic hypertension at one year postpartum, defined as systolic blood pressures (BP) ≥ 130 mmHg or diastolic BP ≥ 80 mmHg [11]. Postpartum hypertension poses potentially life threatening risks to patients [12] including substantial risk of maternal morbidity, such as maternal cardiac failure [13], stroke or cerebral vascular accidents [14], pulmonary edema, recurrent hospitalizations [15] and maternal death [16]. Patients who survive short-term complications are at risk of long-term cardiovascular disease [17], [18], [19].

New diagnosis of chronic hypertension accounts for over 80 % of the increased risk of cardiovascular disease following HDP [20]. Prior research explored risk and protective factors for chronic hypertension postpartum [21], [22], [23], [24]. These risk factors for chronic hypertension included advanced maternal age ≥ 35 years [25], cesarean birth [26], Type-1 diabetes mellitus, T2DM, gestational diabetes, and multifetal gestation [27], [28]. Persons who self-report as black race have slower resolution of HDP and hypertension postpartum [29], [30].

Several studies that assessed the role of body mass index (BMI) and its impact on HDP postpartum primarily examined hypertension at six weeks postpartum [25], [31], [32]. One of these studies found that postpartum blood pressures peaked higher in patients with BMI ≥ 35 kg/m2 than those with a BMI < 35 kg/m2 [33]. Another study demonstrated that elevated pre-pregnancy or first trimester BMI increased the risk of postpartum preeclampsia [34]. To our best knowledge, there are limited studies that have focused on longer follow-up to examine the association between BMI and a diagnosis of chronic hypertension at one year postpartum. To address this gap, the objective of our study was to examine the association between maternal BMI at one year postpartum and a new diagnosis of chronic hypertension (≥130/80 mmHg) one year following HDP. We hypothesized that higher BMI one year postpartum would be associated with higher rates of a diagnosis of chronic hypertension one-year postpartum.