Postpartum weight change and multimodality cardiac remodeling after hypertensive disorders of pregnancy: a secondary analysis of the POP-HT Trial

Background Women with hypertensive disorders of pregnancy (HDP) face an increased risk of long-term cardiovascular disease, yet modifiable postpartum determinants of cardiac remodeling remain under-researched. Purpose To evaluate the association between postpartum weight change and cardiac remodeling in women with HDP using multimodal cardiac imaging. We hypothesized that increasing postpartum weight gain would be associated with progressively greater adverse cardiac remodeling. Methods A secondary analysis of the POP-HT randomized clinical trial was conducted. Postpartum weight change (kg) was calculated as the difference between weight 1-6 days and 6-9 months postpartum. Primary outcomes were changes in left ventricular (LV) mass and interventricular septal thickness. Secondary outcomes included LV geometry, chamber volumes, left atrial size, and diastolic function. Associations were evaluated using multivariable linear regression adjusted for age, ethnicity, parity, gestational duration, multifetal gestation, HDP subtype, baseline BMI, and baseline imaging values. Results Among 205 women (mean ± SD: age 33±5 years; baseline weight 77.4±18.2 kg; baseline BMI 28.5±6.6 kg/m²), 140 (68%) gained weight. Median weight change across the whole cohort was +2.1 kg (IQR -0.75 to +6.5), corresponding to +5.7±5.2 kg in the weight-gain group and -3.4±3.5 kg in the weight-loss/maintenance group. Each 1 kg increase in weight was independently associated with greater LV wall thickness (interventricular septum +0.036 mm/kg, p=0.007; posterior wall +0.045 mm/kg, p<0.001), higher relative wall thickness (+0.0014/kg, p=0.014), larger left atrial volume (+0.29 mL/kg, p=0.002), and impaired diastolic relaxation (lateral e′ -0.9 mm/s/kg, p=0.002; averaged e′ -0.6 mm/s/kg, p=0.007) from echocardiography. Cardiac magnetic resonance demonstrated concordant structural remodeling, with higher LV mass (+0.66 g/kg, p<0.001), higher height-indexed LV mass (+0.45 g·m⁻¹/kg, p<0.001), and larger LV end-diastolic volume (+0.60 mL/kg, p=0.011) per kg of weight gain. In the weight-gain group, above-median weight gain was associated with greater increases in LV mass (+13.2 g vs +8.0 g) and LV end-diastolic volume (+16.0 mL vs +9.4 mL) compared to below-median gain (p<0.05). Conversely, weight loss was associated with graded volume unloading, including lower LV end-systolic volume (-0.93 mL/kg, p=0.018), modest reductions in LVEF (-0.34%/kg, p=0.042), and lower cardiac index (-0.14 L/min/m²/kg, p=0.004; Figure 1 and 2). Conclusion In women with HDP, postpartum weight gain was associated with progressive concentric remodeling and impaired diastolic function, whereas weight loss was linked to reverse remodeling and hemodynamic unloading, highlighting the postpartum period as a key window for weight-focused cardiovascular risk reduction.