Hormone fluctuations over the course of the menstrual cycle. (A) Mean Ln(estradiol) levels over the menstrual cycle (visit 1, 2, 3, and 4) between pulmonary arterial hypertension (PAH) cases (red) and controls (blue) with 95% confidence intervals. (B) Mean Ln(DHEA-S) levels over the menstrual cycle (visit 1, 2, 3, and 4) between PAH cases (red) and controls (blue) with 95% confidence intervals. DHEA-S = dehydroepiandrosterone sulfate; Ln = natural log; PAH = pulmonary arterial hypertension.