Fig. 1

Flow chart of the study population that includes healthy primiparous women with singleton pregnancies. We excluded women with suspected vascular disease in early gestation,defined as one of the following conditions: chronic hypertension, identified as systolic blood pressure (BP) ≥140 or diastolic BP≥90 or BP medication in early gestation, registration of chronic hypertension by checkbox at the first antenatal visit or a corresponding diagnostic code after delivery; or chronic renal disease, identified by proteinuria before 20 gestational weeks (2+ on dipstick or 1+ on two consecutive occasions) or a diagnostic code for chronic renal insufficiency after delivery; or pre-gestational diabetes, identified by registration in a checkbox at first antenatal visit or a corresponding diagnostic code after delivery; or systemic lupus erythematosus as registered in a check box or a corresponding diagnostic code after delivery