Background. Information on physical activity (PA) during pregnancy and subsequent maternal birth outcomes (such as cesarean rate, labor duration) is plentiful in the literature, but consensus among studies is lacking. Poor exposure analytic methods may be a source of conflicting results. Objective. To estimate associations between PA during pregnancy and maternal birth outcomes using appropriate statistical methods. Methods . Detailed 7-day PA recalls were administered to pregnant women at two time points: 17–22 and 27–30 weeks’ completed gestation. Covariables and labor outcomes were obtained by a combination of self-administered questionnaires and medical record abstraction. Physical activity was treated in analyses as a continuous, non-linear variable. We analyzed separately 8 different exposures: total hours/week PA at each time point, hours/week moderate-to-vigorous PA (MVPA) at each time point; total hours/week recreational PA at each time point, and finally hours/week recreational MVPA at each time point. Outcomes included induction, labor duration, augmentation, operative vaginal delivery (OVD), cesarean birth, episiotomy, and laceration severity. Covariables for each model were selected using directed acyclic graphs (DAGs); variables in final models were chosen through backwards stepwise selection using analysis of deviance. Sensitivity analyses explored the effects of excluding women reporting extremely large PA volumes and of excluding women reporting zero hours/week PA. Results. Physical activity during pregnancy was associated with a decreased risk of induction. Recreational PA at the second time point only was associated with a decreased risk of augmentation. PA during pregnancy was associated with longer labor durations, but our measure of labor duration was crude and we do not consider this result definitive. PA was not associated in these data with episiotomy, OVD, or cesarean. PA may be associated with increased laceration severity, but effects were quite small. Conclusions. Lack of consensus in the literature on the associations between PA and maternal birth outcomes may be partially because of categorical treatment of the exposure and lack of attention to gestational age at time of exposure.
|Advisor:||Siega-Riz, Anna Maria|
|Commitee:||Evenson, Kelly R., Goodnight, William, Hales, Derek, Olshan, Andrew|
|School:||The University of North Carolina at Chapel Hill|
|School Location:||United States -- North Carolina|
|Source:||DAI-B 72/01, Dissertation Abstracts International|
|Subjects:||Medicine, Public health, Epidemiology|
|Keywords:||Birth outcomes, Cesarean, Labor duration, Labor induction, Maternity, Physical activity, Pregnancy|
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