The data on maternal weight gain are conflicting. Two meta-analyses and several observational studies found no difference in maternal weight gain. However, these meta-analyses did not differentiate between exercise type, intensity, duration or pre-pregnancy fitness levels when examining the results. All these factor could have and impact on maternal weight gain. Some observational studies found that woman who exercised during pregnancy gained less weight than did the controls. These studies included women who exercised prior to pregnancy and continued to do so during pregnancy . One prospective, observational study compared fit woman who continued exercising at least 3 time per week for 30 minutes through the 37th week of pregnancy to woman who stopped exercising during pregnancy and found that the rate of weight gain was significantly less in the second and third trimesters in the cohort who continued to exercise. The total weight gain was approximately 3 kg less in the exercise group but was still within the recommended range of maternal weight gain. One study reported approximately 1.8 kg less weight gain in primiparas who participated in a nonendurance exercise program at least 2 hours per week when compared with sedentary controls. Weight gain probably related to amount, intensity and timing of exercise during pregnancy. In all these studies the woman volunteered to participate in the studies and chose to enter the exercise group. It is possible that these woman had different eating habits and healthier life-styles in general, thus leading to less weight gain regardless of exercise status.
Studies reported varying results with regard to labor-and-delivery-related outcomes. For example, 1 prospective, observational study of 131 healthy, low-risk, fit women compared those who continued to exercise at >50% of maximum capacity for at least 30 minutes, 3 times a week, for during the latter half of pregnancy to those who stopped exercising during pregnancy. The study found that women who continued to exercise during pregnancy needed fewer epidurals and had more vaginal deliveries, fewer forceps deliveries and fewer cesarean sections. In addition, these women had a shorter active phase of labor and fewer episiotomies. In contrast, another prospective, observational study of 750 military women on active duty compared those who did not exercise during pregnancy and those who continued. The study revealed that women who exercised during pregnancy required more inductions of labor and had a longer first stage of labor but showed no difference in mode of delivery, second or third stage of labor, or epidural use.
A prospective trial of 800 women reported lower cesarean section rates in the high-exercise group as compared to lower-exercise groups and nonexercising controls (6.7% in the high exercise groups vs. 28% in the control group). Women participating in a nonendurance exercise program had more vaginal deliveries, required less labor augmentation and had shorter first (approximately 7 hours shorter ) and second (approximately 1 hour shorter) stages of labor than did the controls. Other studies, including a small, randomized trial, found no difference in epidural use, cesarean section rate or duration of labor. The incongruent results in these studies could be explained by different pre-pregnancy fitness levels; the intensity, type and duration of exercise in pregnancy; and controls used. Caution must be used when extrapolating the results of any of these studies to the general population.
Conclusion
The disparate results found in many of the studies examining the effects of exercise during pregnancy could be based on several factors. First, not all exercise is the same, and different types of exercise, intensity and duration may have different impacts on pregnancy. In addition, the highly variable definitions of exercise make comparisons between studies, exposures and results challenging. Furthermore, the women who participate in the studies are volunteers, leading to potential selection bias. The women who chose to exercise and continued exercise through pregnancy may have been inherently different from their nonexercising peers in several ways, including views on health, dietary habits, body composition and preferences about anesthesia during labor. The women who exercised may also have been more athletically inclined, making it difficult to distinguish the effects of exercise vs. physical fitness on pregnancy outcomes. The women in these studies were generally Caucasian, middle to upper class and worked outside the home. All these factors make it difficult to apply the results of the studies are needed to refine our understanding of the effects of exercise during pregnancy, to examine exercise during pregnancy in different patient populations and to elucidate the long-term outcomes for both mother and infant.
A few general conclusions can be made from the literature. From the available evidence, moderate exercise in the low-risk pregnancy appears to be safe for both the fetus and mother. There are several physiologic factors that may be protective for women who exercise during pregnancy. Although there is decreased uterine blood flow during strenuous exercise, there appears to be compensatory mechanisms, such as preferential shift of blood flow to the placenta and increased oxygen extraction. Maternal conditioning may lessen the exercise induced decrease in uterine blood flow. Also, thermoregulatory adaptations appear in early pregnancy, may confer a protective effect during fetal development and may limit thermal stress in women who continue to exercise throughout pregnancy.
The data regarding maternal and fetal outcomes is quite varied. In the low-risk pregnancy there are no apparent adverse pregnancy outcomes associated with moderate exercise-no increased risk of miscarriage, preterm labor, preterm birth or intrauterine growth restriction. There is no consistent effect on fetal weight . Exercise has been shown to improve maternal fitness and well-being but does not have a clear effect on maternal weight gain or labor outcomes.
The data on maternal weight gain are conflicting. Two meta-analyses and several observational studies found no difference in maternal weight gain. However, these meta-analyses did not differentiate between exercise type, intensity, duration or pre-pregnancy fitness levels when examining the results. All these factor could have and impact on maternal weight gain. Some observational studies found that woman who exercised during pregnancy gained less weight than did the controls. These studies included women who exercised prior to pregnancy and continued to do so during pregnancy . One prospective, observational study compared fit woman who continued exercising at least 3 time per week for 30 minutes through the 37th week of pregnancy to woman who stopped exercising during pregnancy and found that the rate of weight gain was significantly less in the second and third trimesters in the cohort who continued to exercise. The total weight gain was approximately 3 kg less in the exercise group but was still within the recommended range of maternal weight gain. One study reported approximately 1.8 kg less weight gain in primiparas who participated in a nonendurance exercise program at least 2 hours per week when compared with sedentary controls. Weight gain probably related to amount, intensity and timing of exercise during pregnancy. In all these studies the woman volunteered to participate in the studies and chose to enter the exercise group. It is possible that these woman had different eating habits and healthier life-styles in general, thus leading to less weight gain regardless of exercise status.
Studies reported varying results with regard to labor-and-delivery-related outcomes. For example, 1 prospective, observational study of 131 healthy, low-risk, fit women compared those who continued to exercise at >50% of maximum capacity for at least 30 minutes, 3 times a week, for during the latter half of pregnancy to those who stopped exercising during pregnancy. The study found that women who continued to exercise during pregnancy needed fewer epidurals and had more vaginal deliveries, fewer forceps deliveries and fewer cesarean sections. In addition, these women had a shorter active phase of labor and fewer episiotomies. In contrast, another prospective, observational study of 750 military women on active duty compared those who did not exercise during pregnancy and those who continued. The study revealed that women who exercised during pregnancy required more inductions of labor and had a longer first stage of labor but showed no difference in mode of delivery, second or third stage of labor, or epidural use.
A prospective trial of 800 women reported lower cesarean section rates in the high-exercise group as compared to lower-exercise groups and nonexercising controls (6.7% in the high exercise groups vs. 28% in the control group). Women participating in a nonendurance exercise program had more vaginal deliveries, required less labor augmentation and had shorter first (approximately 7 hours shorter ) and second (approximately 1 hour shorter) stages of labor than did the controls. Other studies, including a small, randomized trial, found no difference in epidural use, cesarean section rate or duration of labor. The incongruent results in these studies could be explained by different pre-pregnancy fitness levels; the intensity, type and duration of exercise in pregnancy; and controls used. Caution must be used when extrapolating the results of any of these studies to the general population.
Conclusion
The disparate results found in many of the studies examining the effects of exercise during pregnancy could be based on several factors. First, not all exercise is the same, and different types of exercise, intensity and duration may have different impacts on pregnancy. In addition, the highly variable definitions of exercise make comparisons between studies, exposures and results challenging. Furthermore, the women who participate in the studies are volunteers, leading to potential selection bias. The women who chose to exercise and continued exercise through pregnancy may have been inherently different from their nonexercising peers in several ways, including views on health, dietary habits, body composition and preferences about anesthesia during labor. The women who exercised may also have been more athletically inclined, making it difficult to distinguish the effects of exercise vs. physical fitness on pregnancy outcomes. The women in these studies were generally Caucasian, middle to upper class and worked outside the home. All these factors make it difficult to apply the results of the studies are needed to refine our understanding of the effects of exercise during pregnancy, to examine exercise during pregnancy in different patient populations and to elucidate the long-term outcomes for both mother and infant.
A few general conclusions can be made from the literature. From the available evidence, moderate exercise in the low-risk pregnancy appears to be safe for both the fetus and mother. There are several physiologic factors that may be protective for women who exercise during pregnancy. Although there is decreased uterine blood flow during strenuous exercise, there appears to be compensatory mechanisms, such as preferential shift of blood flow to the placenta and increased oxygen extraction. Maternal conditioning may lessen the exercise induced decrease in uterine blood flow. Also, thermoregulatory adaptations appear in early pregnancy, may confer a protective effect during fetal development and may limit thermal stress in women who continue to exercise throughout pregnancy.
The data regarding maternal and fetal outcomes is quite varied. In the low-risk pregnancy there are no apparent adverse pregnancy outcomes associated with moderate exercise-no increased risk of miscarriage, preterm labor, preterm birth or intrauterine growth restriction. There is no consistent effect on fetal weight . Exercise has been shown to improve maternal fitness and well-being but does not have a clear effect on maternal weight gain or labor outcomes.
การแปล กรุณารอสักครู่..