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Exposure Analysis Methods Impact Associations between Maternal Physical Activity and Cesarean Delivery


Bovbjerg, Marit L.; Siega-Riz, Anna Maria; Evenson, Kelly R.; & Goodnight, William (2015). Exposure Analysis Methods Impact Associations between Maternal Physical Activity and Cesarean Delivery. Journal of Physical Activity and Health, 12(1), 37-47. PMCID: PMC4590730


BACKGROUND: Previous studies report conflicting results regarding a possible association between maternal physical activity (PA) and cesarean delivery.
METHODS: 7-day PA recalls were collected by telephone from n=1205 pregnant women from North Carolina, without prior cesarean, during two time windows: 17-22 weeks and 27-30 weeks completed gestation. PA was treated as a continuous, non-linear variable in binomial regressions (log-link function); models controlled for primiparity, maternal contraindications to exercise, pre-eclampsia, pre-gravid BMI, and percent poverty. We examined both total PA and moderate-to-vigorous PA (MVPA) at each time. Outcomes data came from medical records.
RESULTS: The dose-response curves between PA or MVPA and cesarean risk at 17-22 weeks followed an inverse J-shape, but at 27-30 weeks the curves reversed and were J-shaped. However, only (total) PA at 27-30 weeks was strongly associated with cesarean risk; this association was attenuated when women reporting large volumes of PA (>97.5th percentile) were excluded.
CONCLUSION: We did not find evidence of an association between physical activity and cesarean birth. We did, however, find evidence that associations between PA and risk of cesarean may be non-linear and dependent on gestational age at time of exposure, limiting the accuracy of analyses that collapse maternal PA into categories.


Reference Type

Journal Article

Year Published


Journal Title

Journal of Physical Activity and Health


Bovbjerg, Marit L.
Siega-Riz, Anna Maria
Evenson, Kelly R.
Goodnight, William