Statistical Analysis Plan for the Blood Pressure Postpartum (BP2) study

Background Hypertensive Disorders of Pregnancy (HDP) complicate 5-10% of pregnancies globally: 2-5% preeclampsia, 3% gestational hypertension, and 0.5-2% chronic hypertension. It is epidemiologically well established that adverse health effects of HDP do not end with the pregnancy: these conditions are associated with increased lifetime cardiovascular disease (CVD) risks. However, intervention trial data in the early years postpartum after HDP, focussed on early intervention to reduce women’s ongoing CVD risks after HDP, is sparse. Methods The Blood Pressure Postpartum Trial (BP 2 ) is a 3-arm randomised controlled trial investigating three different methods of follow-up and lifestyle behaviour change in the first 12 months postpartum following a pregnancy affected by HDP. The trial was prospectively registered on the Australian and New Zealand Clinical trials registry (registration: ACTRN12618002004246) and the study protocol has previously been published (Henry A et al, Pregnancy Hypertension 2020; 22: 1-6). This manuscript details the pre-analysis, pre-specified Statistical Analysis Plan.