OP21.01: Pre‐pregnancy exercise stress testing is related to normal physiological adaptation from pre‐pregnancy to mid‐pregnancy

Abstract

It is suggested that maternal cardiovascular(CV) changes in pregnancy are related to pregnancy outcome, specifically failure of these important adaptive changes may result in pre-eclampsia(PE) or fetal growth restriction (FGR). To explore if maternal physiological CV maladaptation could be anticipated prior to pregnancy, we investigated pre-pregnancy (PP) exercise stress testing prior to conception, in association with subsequent pregnancy induced CV changes. We recruited non-smokers with no CV co-morbidities into a pre-conception study. PP, all participants had non-invasive measurements of cardiac output (CO), stroke volume (SV), total peripheral resistance (TPR), heart rate (HR) and brachial blood pressure (BP) at rest. These were repeated during and after a 3-minute Dundee step test. Delta (δ) values were calculated between resting and exercise measurements to deduce exercise stress response. At 22 weeks' gestation resting CV measurements were repeated. Delta values induced by exercise PP were related to longitudinal changes induced by pregnancy (PP to 22wks). There were significant correlations between PP exercise induced CV changes, and PP to 22 weeks induced CV changes for CO, HR, BP and TPR. The strongest correlation was between the PP δTPR during exercise & the pregnancy induced adaptation of TPR from PP to 22 wks (r=0.669, p<0.001.) We explored if the δTPR relationship was also present at 6 weeks gestation and found similar results, though with weaker correlations (r=0.568, P<0.001). TPR exercise response strongly correlates to physiological change in TPR from PP to mid-pregnancy (22wks). This correlation is already present by 6 wks gestation, though to a weaker extent. There are also weaker but significant associations between PP exercise CO, BP and mid-pregnancy adaptation of the same parameters. Therefore, PP exercise testing may be valuable in providing insight into normal physiological adaptation to pregnancy.