Cardiorespiratory Fitness, Exercise Hemodynamics and Birth Outcomes: The Coronary Artery Risk Development in Young Adults (CARDIA) Study

Abstract

Objective

Determine 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; <37 weeks gestation) and small for gestational age (SGA; birthweight <10 ^th percentile) delivery.

Design

Prospective, longitudinal

Setting

Multi-site, observational cohort study initially consisting of 2,787 Black and White women aged 18–30 at baseline (1985–86) and followed for 25 years (Y25; 2010–11).

Population

768 women nulliparous women at baseline who reported ≥1 live birth(s) by the Y25 exam.

Methods

We used Poisson regression to determine associations of exposures with PTB/SGA.

Main Outcome Measures

PTB and/or SGA births

Results

Women with PTB (n=143) and/or SGA (n=88) were younger, completed fewer years of education, and more likely to be black versus women without PTB/SGA (n=546). Women with PTB/SGA had lower fitness; 501±9s vs 535±6s, p<0.002, and higher submaximal SBP than women without PTB/SGA; 144±1 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 <5 years before the index birth.

Conclusions

Neither fitness nor hemodynamic responses to exercise, a median of 5 years preceding pregnancy, were associated with PTB/SGA. These findings indicate excess likelihood of PTB/SGA is not detectable by low fitness or exercise hemodynamic responses 5 years preceding pregnancy, but exercise testing, especially HRR and submaximal SBP, may be more useful conducted closer to the onset of pregnancy.

Funding

CARDIA is supported by the National Heart, Lung, and Blood Institute (NHLBI) HHSN268201300025C, HHSN268201300026C, HHSN268201300027C, HHSN268201300028C, HHSN268201300029C, HHSN268200900041C, and partially supported by the Intramural Research Program of the National Institute on Aging (NIA) and an intra-agency agreement between NIA and NHLBI (AG0005). The analyses were supported by grants from R01 DK106201 (Gunderson, PI), R01 DK090047 (Gunderson, PI) and K01 DK059944 (Gunderson, PI) from the National Institute of Diabetes, Digestive and Kidney Diseases. ALC is supported by an American Heart Association Strategically Focused Research Network Grant 14SFRN20480260 (PI: Greenland).