Cardiorespiratory fitness, exercise haemodynamics and birth outcomes: the Coronary Artery Risk Development in Young Adults Study

ObjectiveDetermine associations of cardiorespiratory fitness, exercise systolic blood pressure (SBP) and heart rate recovery (HRR) following a maximal exercise test performed years preceding pregnancy with odds of preterm birth (PTB; <37weeks' gestation) and small for gestational age (SGA; birthweight <10(th) percentile) delivery. DesignProspective, longitudinal. SettingMulti-site, observational cohort study initially consisting of 2787 black and white women aged 18-30 at baseline (1985-86) and followed for 25years (Y25; 2010-2011). Population768 nulliparous women at baseline who reported 1 live birth by the Y25 exam. MethodsWe used Poisson regression to determine associations of exposures with PTB/SGA. Main outcome measuresPTB and/or SGA births. ResultsWomen with PTB (n=143) and/or SGA (n=88) were younger, had completed fewer years of education and were more likely to be black versus women without PTB/SGA (n=546). Women with PTB/SGA had lower fitness (5019 versus 5356seconds, P<0.002) and higher submaximal SBP than women without PTB/SGA (1441 versus 142 +/- 1mmHg, P<0.04). After adjustment, no exercise test variables were associated with PTB/SGA, though the association with HRR and submaximal SBP approached significance in the subset of women who completed the exercise test <5years before the index birth. ConclusionsNeither fitness nor haemodynamic responses to exercise a median of 5years preceding pregnancy, were associated with PTB/SGA. These findings indicate excess likelihood of PTB/SGA is not detectable by low fitness or exercise haemodynamic responses 5years preceding pregnancy, but exercise testing, especially HRR and submaximal SBP, may be more useful when conducted closer to the onset of pregnancy. Tweetable abstractExercise testing conducted >5years before pregnancy may not detect women likely to have PTB/SGA. Tweetable abstract Exercise testing conducted >5years before pregnancy may not detect women likely to have PTB/SGA.