Objective: To assess the association between participation in aerobic exercise during the first two
trimesters of pregnancy and type of delivery in nulliparous women.
Design: Nonexperimental, retrospective.
Setting: A large metropolitan area in the
Participants: 137 nulliparous women.
Outcome Measures: Method of delivery.
Results: An unadjusted odds ratio showed that
sedentary women (n = 93) were 2.05 times more likely to deliver via cesarean section than active
women (n = 44), but this relationship was not statistically significant. Through logistic regression
analysis with control for the mother's prepregnancy exercise program, age, use of epidural anesthesia,
change in prepregnancy to delivery body mass index, labor length, whether labor was induced,
and the hospital of birth, the odds of cesarean delivery were found to be 4.5 times greater for sedentary
women than for active women.
Conclusion: Regular participation in physical activity during the first two trimesters of pregnancy
may be associated with reduced risk for cesarean delivery in nulliparous women. JOG" 29,
250-264; 2000.

Conclusions and Implications
The implications of this study suggest that pregnant women should exercise. Nurses and physicians can influence pregnant women's activity patterns through education and encouragement. A physical activity counseling program has been designed by the Centers for Disease Control and Prevention to be delivered by health professionals in the context of an office visit. Topics such as safety, exercise options during bad weather, and overcoming barriers to physical activity are addressed in the curriculum (Patrick et al., 1994). This curriculum is pre-scribed in accordance with the patient’s previous exercise
regimen. Women who exercised before becoming pregnant should be encouraged to continue, and those who are sedentary could be motivated to begin exercising. It is important that pregnant women know they may exercise during pregnancy and by doing so could reduce their risk of cesarean section. Researchers (Clapp, 1990; Hall & Kaufmann, 1987; Jackson et al., 1995; Rice & Fort, 1991; Wallace et al., 1986; Zeanah & Schlosser, 1993) indicate that the benefits of regular exercise for the
healthy, pregnant woman appear to outweigh the risks.
However, some contraindications for exercise do exist during pregnancy. ACOG (1994) offers safety-related recommendations that admittedly do not have a firm basis in randomized clinical trials. The following six medical or obstetric conditions have been identified as contraindications to exercise during pregnancy: pregnancy-induced hypertension, preterm rupture of membranes, preterm labor during a prior or current pregnancy, incompetent cervix, persistent 2nd or 3rd trimester bleeding, or fetal growth restriction. The ACOG recommendations are general in nature. It is suggested that the intensity of exercise should be modified according to maternal symptoms and should not continue to fatigue or exhaustion. Exercise in the supine position should be avoided after the 1st trimester, and caution should be used for those activities that require significant balance. Exercise that involves the potential for even mild abdominal trauma should be avoided. Other recommendations for nutrition, heat dissipation, and resuming physical activity after birth are offered by ACOG (1994).
Future suggested research includes replicating the current study with a larger sample that is more ethnically diverse and using more precise physical activity measurement instruments. Additionally, clinical trials could be used to demonstrate causal relationships of different intensities, durations, or modes of physical activity with pregnancy outcomes.