The Influence of Race on Gestational Exercise and Birth Outcomes

Abstract

In the United States, long-standing racial disparities in adverse birth outcome are prominent among the non-Hispanic Black (NHB) population, particularly when compared to Caucasians. Although maternal physical activity during pregnancy has been shown to improve birth measures and reduce the risk of adverse birth outcome among both NHBs and the general population, there exists a gap in the current literature as to whether the degree of response to maternal physical activity is the same among different racial groups. The primary purpose of this study is to investigate the influence of maternal exercise on birth outcomes in NHB infants compared to Caucasian infants. Secondary purposes of this study are to investigate the effect of maternal exercise on preterm infant health and to compare both overall and modality-specific compliance among NHB and Caucasian participants enrolled in exercise interventions. We hypothesized that infants born to NHB exercisers would have similar gestational age and markers of neonatal health at birth relative to infants of Caucasian exercisers, and that any racial disparities observed would be found among control participants. We also hypothesized that preterm infants born to exercisers would have reduced hospital stay and improved measures of health compared to control, and that compliance among participants would be similar regardless of race. Participants engaged in 150 minutes of moderate intensity exercise (60-85% HRmax) through three 50 minutes sessions per week; beginning at 16 weeks gestation and continuing through delivery. Controls did not engage in exercise training. Maternal measures of age, pre-pregnancy BMI, maternal/parental education levels, and compliance were collected from questionnaires and training logs. Infant measures of gestational age, length of hospital stay, head to abdominal circumference ratio, birth weight, mode of delivery, and 1 and 5 minute Apgar scores were collected from birth records. Mann-Whitney U and independent t-tests were used to compare maternal and infant measures between races, while ANOVA and chi-square tests were used to analyze compliance and proportions of adverse birth. Analyses also included binomial logistic and linear regressions. With the exception of birth weight, which was significantly lower among NHB infants (p=0.036) due to a higher prevalence of low birth weight, there were no differences in measures of neonatal health and adverse birth outcome between infants born to compliant Caucasian exercisers and those born to compliant NHB exercisers. A pattern of reduced hospital stay and improved markers of infant health was observed among preterm infants born to exercisers, and modality-specific compliance was found to vary significantly both within and between races. The results of this study suggest that 1) In addition to infants of different races responding similarly to maternal exercise, racial disparities in birth outcomes may be partially attenuated by maternal exercise; with maternal exercise influencing birth outcomes by fostering more favorable gestational age at birth. 2) Infants exposed to maternal exercise can still potentially gain health benefits when born preterm. 3) Among NHB populations, aerobic exercise should be recommended in order to maximize the likelihood of compliance with physical activity guidelines and foster greater improvement in birth outcomes. Further research is needed, but our study supports existing literature that maternal exercise benefits infant health, while adding to our understanding of the degree of response among different races.