Maternal leisure-time exercise and timely delivery.
OBJECTIVE
This study investigated whether, in a general obstetric population, exercise in pregnancy affects the timeliness of delivery. The hypothesis was that maternal exercise would not raise the risk of preterm birth.


METHODS
A community cohort of 557 prenatal patients was followed up until the time of delivery. Data were collected on exercise in each trimester: none, low-moderate (< 1000 kcal [4184 kJ]/wk in energy expenditure), or heavy (> or = 1000 kcal/wk). Timely delivery was adopted as an outcome criterion. Thus, in the analysis, a term birth was treated as optimal and survival techniques were used to estimate risks for both preterm and postdates delivery.


RESULTS
No association was found between low-moderate exercise and gestational length. Heavier exercise appeared to reduce, rather than raise, the risk of preterm birth. The adjusted relative risk among conditioned heavy exercisers was 0.11 (95% confidence interval = 0.02, 0.81). After term, conditioned heavy exercisers delivered faster than nonexercisers.


CONCLUSIONS
The most important finding was the lack of evidence that vigorous maternal exercise is a risk factor for preterm delivery. A promising finding was that conditioned heavy exercisers have timely deliveries.
Columbia School of Public Health, New York, NY, USA. m_hatch@smtplink.mssm.edu
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D000328:Adult; D015331:Cohort Studies; D036861:Delivery, Obstetric; D004522:Educational Status; D004734:Energy Metabolism; D015444:Exercise; D005260:Female; D006801:Humans; D009518:New York; D010414:Pennsylvania; D011247:Pregnancy; D011256:Pregnancy Outcome; D016016:Proportional Hazards Models; D012307:Risk Factors; D012907:Smoking; D013997:Time Factors