Continuing regular exercise during pregnancy: effect of exercise volume on fetoplacental growth. Beginning regular exercise in early pregnancy: effect on fetoplacental growth. Heart volume and physical fitness of parturients. The effect of participation in a regular exercise program upon aerobic capacity during pregnancy. Swimming and physical fitness during pregnancy. Antenatal exercise and birthweight. Aerobic exercise and submaximal functional capacity in overweight pregnant women: a randomized trial. Maternal and fetal responses to a maternal aerobic exercise program. Physical and psychological changes with vigorous exercise in sedentary primigravidae.
The purpose of this study was to test the null hypothesis that the volume of exercise at different times during pregnancy has no effect on fetoplacental growth.
                Seventy-five women who exercised regularly were evaluated before pregnancy and randomly assigned at 8 weeks' gestation to one of 3 exercise regimens for the remainder of pregnancy. Primary outcome variables included placental growth rate, birth weight, and placental volume at term.
                The offspring of the women who were randomly assigned to a high volume of exercise in mid and late pregnancy were significantly lighter (3.39 kg vs 3.81 kg) and thinner (8.3% fat vs 12.1% fat) than those offspring born of women who were randomly assigned to reduce their exercise volume after the 20th week. Maternal weight gain, fresh placental volumes, and histomorphometric indices of placental function were greater in the high-low group.
                These data indicate that a high volume of moderate-intensity, weight-bearing exercise in mid and late pregnancy symmetrically reduces fetoplacental growth, whereas a reduction in exercise volume enhances fetoplacental growth with a proportionally greater increase in fat mass than in lean body mass. Our purpose was to test the null hypothesis that beginning regular, moderate-intensity exercise in early pregnancy has no effect on fetoplacental growth. Study Design: Forty-six women who did not exercise regularly were randomly assigned at 8 weeks either to no exercise (n = 24) or to weight-bearing exercise (n = 22) 3 to 5 times a week for the remainder of pregnancy. Outcome variables included antenatal placental growth rate and neonatal and placental morphometric measurements.
                The offspring of the exercising women were significantly heavier (corrected birth weight: 3.75 +/- 0.08 kg vs 3.49 +/- 0.07 kg) and longer (51.8 +/- 0.3 cm vs 50.6 +/- 0.3 cm) than those born to control women. The difference in birth weight was the result of an increase in both lean body mass and fat mass. In addition, midtrimester placental growth rate was faster (26 +/- 2 cm(3)/wk vs 21 +/- 1 cm(3)/wk) and morphometric indexes of placental function were greater in the exercise group. There were no significant differences in neonatal percentage body fat, head circumference, ponderal index, or maternal weight gain.
                These data indicate that beginning a moderate regimen of weight-bearing exercise in early pregnancy enhances fetoplacental growth. One hundred and three primigravidae were studied to establish the correlation between physical fitness and heart volume. Twenty-three of the mothers were allocated at random to the exercise group and 21 to control group 1, between the 10th and 14th weeks of pregnancy. In addition, 59 mothers were allocated to control group 2, which was formed two weeks before term. The exercise group underwent a rather strenuous training programme during pregnancy. Physical fitness was measured by work tests on a bicycle ergometer two weeks before term. The heart volume was determined radiologically on the 6th day post partum. There was a positive correlation between physical fitness and the relative heart volume, which was greatest when physical fitness was measured by a method which takes the level of training into consideration. The relative heart volume of the exercise group was almost significantly greater than that of control group 1. The physical performance of the exercise group was very significantly greater than in the control groups. There was no significant correlation between either physical fitness or relative heart volume and the duration of pregnancy or the weight of newborn. This study examined the questions of whether pregnancy decreases physical fitness, as measured by maximal oxygen consumption, between the second and third trimesters, and whether maintaining a regular exercise program during the second half of pregnancy affects fitness. At the beginning of their second trimester, pregnant women were randomly assigned to either a nonexercising control group or an exercising group. They completed a maximal progressive exercise test on a cycle ergometer at 20 and 30 weeks, during which pulmonary parameters of aerobic capacity were measured. The exercising group demonstrated greater improvement in aerobic capacity than did the control group, manifested by increases in tidal volume and oxygen consumption and a stable ventilatory equivalent for oxygen. Pregnancy did not reduce maximal oxygen consumption between the second and third trimesters of pregnancy. nan Does strenuous antenatal exercise reduce birthweight? Does reducing maternal exercise increase birthweight? What to advise about exercise during pregnancy? We recruited 117 women who intended to exercise 5 or more times weekly during pregnancy to a study of whether reducing the amount of maternal exercise during pregnancy is associated with an increase in birthweight. Only 61/117 (52%) of women agreed to be randomised to either continue or to reduce (to 3 or fewer sessions of exercise weekly) their intended pregnancy exercise program. Most women who refused randomisation did not want to risk being asked to reduce their exercise during pregnancy. Within the randomised trial, there was no statistically significant difference between the mean birthweight of babies born to women who continued and those who reduced their intended exercise program. The high rate of refusal of randomisation limits the power of the study to find a difference in birthweight, limits the generalisability of the results and shows that many women intending to exercise at this level during pregnancy have an uncompromising attitude to exercise. To evaluate the effects of aerobic training on submaximal cardiorespiratory capacity in overweight pregnant women.
                We conducted a randomized clinical trial in a referral center prenatal clinic during the period 2000-2002. Of 132 overweight (body mass index 26-31 kg/m2) but otherwise healthy volunteers, at 20 years of age or older, with gestational age of 20 weeks or less, and without diabetes or hypertension, 92 consented to participate and were randomized. Intervention consisted of 3 one-hour aerobic exercise sessions per week; the control group received weekly relaxation and focus group discussions. The main outcome measure was submaximal exercise capacity evaluated by oxygen uptake at the anaerobic (first ventilatory) threshold during cardiopulmonary treadmill testing 12 weeks after randomization.
                Oxygen uptake at the anaerobic threshold increased 18% (15.9 +/- 2.6 to 18.1 +/- 3.1 mL . min(-1) . kg(-1)) in the exercise group but decreased 16% (16.9 +/- 3.0 to 15.8 +/- 2.6 mL . min(-1) . kg(-1)) among the control group. Oxygen consumption at the anaerobic threshold, adjusted through analysis of covariance for baseline oxygen uptake, was 2.68 (95% confidence interval 1.23 to 4.12) mL . min(-1) . kg(-1) greater in the exercise group. Women in the exercise group were approximately 5 times more likely than those in the control group to have regular or good cardiorespiratory capacity (12/38 versus 2/38; relative risk 5.2, 95% confidence interval 1.2 to 22.0, number needed to treat 5).
                Aerobic training in overweight pregnant women substantially increases submaximal exercise capacity, overcoming the otherwise negative effects of pregnancy in this regard. Additional studies are required to evaluate its effect on major clinical outcomes. To investigate the effects of exercise on the pregnant woman and her fetus, 20 pregnant women were studied during the second and third trimesters. Twelve of the women participated in an aerobic exercise program while eight women did not perform any regular exercise and served as a control group. On the basis of submaximal exercise test results, an 18% improvement and a 4% decline in absolute aerobic capacity (liters of oxygen per minute) were observed in the exercise and control groups, respectively. Functional aerobic capacity (milliliters of oxygen per kilogram per minute) rose 8% in the exercise group and declined 10% in the control group. A small but significant rise in fetal heart rate was measured during the exercise sessions. A comparison of pregnancy outcome of the two groups showed no differences in labor duration, Apgar scores, or fetal growth. The present study examined the effects of exercise on physical and psychological variables in sedentary primigravidae (PRA).
                A total of nine women randomly assigned to an exercise (E) (mean age = 31.3 +/- 3.1 yr) and six subjects randomly assigned to a control (C) group (mean age = 27.8 +/- 3.1 yr) fulfilled all requirements for the study. Exercise included a variety of exercise activities performed to a target heart rate of 150-156 beats x min(-1), three times per week for 15 wk.
                Results showed no significant differences between E and C groups in physical characteristics initially. A repeated measures ANOVA showed a significant group effect (P < 0.05) and a significant group by time interaction (P = 0.001) with the E group showing a significantly longer amount of time on the PWC150 test than the C group. There was no significant group, time, or group by time interaction for lactate accumulation. This occurred, despite the fact that the E group spent 56% longer on the PWC150 test and the C group spent 30% less time on the same test at the conclusion of the study. Finally, the E group in comparison to the C group showed more favorable improvements in several items related to health and well-being on the Body Cathexis Scale. There were no significant differences between E and C groups in any pregnancy outcome measures. All babies were delivered healthy at term.
                These data suggest that a vigorous exercise program can lead to significant improvements in aerobic fitness at similar lactate concentrations compared to a control group and can be well tolerated by low risk sedentary PRA without any deleterious effects occurring to herself or unborn child.
Regular aerobic exercise during pregnancy appears to improve (or maintain) physical fitness. Available data are insufficient to infer important risks or benefits for the mother or infant. Larger and better trials are needed before confident recommendations can be made about the benefits and risk of aerobic exercise in pregnancy.