Effects of Exercise on Pregnancy

¶ … Pregnancy

There are many positive effects of exercise during pregnancy. It can decrease the time it takes to get back into shape after giving birth. It may also decrease the amount of time spent in the hospital. In addition, it can increase Apgar scores and birth weight, as well as decrease discomfort during pregnancy. Women who exercise during pregnancy also find that they have less difficulty and length of labor. Research shows that exercise has many benefits for pregnant women.

However, as both exercise and pregnancy exert stresses on the body, the cumulative effects must be taken into consideration when analyzing the relationship between exercise and pregnancy. In general, research about this topic is sparse, and animal studies have presented conflicting findings. Chronic disorders such as diabetes, hypertension, and heart disease are the most obvious reasons to discourage persons at risk from intense rehabilitative exercising while pregnant. In addition, small or underweight women should be warned of the dangers, as these women bear more premature and low birth weight infants than other women.

Physiological Changes During Pregnancy

Many physiological changes take place during pregnancy. Therefore, it is very important pregnant women to be aware of these physiological changes. These changes include increased hormonal blood volume, increased heart rate and cardiac output, lower hematocrit levels, decline in exercise capacity, and an increase in elasticity in the connective tissue.

Because of these changes, pregnant women must have an individualized exercise routine designed to meet her specific needs. For instance, a woman who has exercised vigorously on a daily basis for most of her life prior to pregnancy may be able to maintain a higher level of exercise intensity than another woman who has exercised little in the past. When researching the effects of exercise on pregnancy, these physiological factors must be taken into consideration.

Statement of Purpose

Previous research regarding the effects of exercise on pregnancy outcomes has been inconsistent. Because of this, the appropriateness of exercise during pregnancy is controversial. There are many factors that affect a woman's ability to exercise and her body's response to exercise. Placental blood flow, the potential for hyperthermia and trauma, changes in coordination and balance, body position during exercise, increased nutritional requirements, and the potential for back and pelvic pain must all be taken into consideration when examining the effects of exercise on pregnancy. This paper aims to review five journal articles to examine the relationship between exercise and pregnancy.

Hypothesis

Most women know that exercise is beneficial. However, once pregnant, many women are concerned about the safety of exercise to her and her baby. This paper aims to show that exercise will make the pregnancy easier, while stressing that exercising during pregnancy is a special situation and should be approached with caution.

II-Literature Review

This chapter will review five journal articles that are concerned with the effects of exercise on pregnancy, in an attempt to reach a conclusion regarding the physiological and theoretical concerns regarding exercise and pregnancy.

Article #1

Reference and Purpose of Study -- In David Araujo's article, "Expecting Questions About Exercise and Pregnancy?" (1997), the author discusses the importance of following clinical guidelines when recommending exercise pregnancy. According to Araujo, because pregnant women come from different backgrounds, they all have individual fitness needs. Therefore, when advising pregnant women on the effects of exercise, it is important to understand how exercise affects the physiologic adaptations that occur during pregnancy. This article sheds some light on this topic.

Methods -- Araujo looked at two cases to illustrate some of the concerns that must be addressed when examining the effects of exercise on pregnant women and how different women have different needs. He also examined the various changes involved in pregnancy in order to evaluate the relationship between exercise and pregnancy.

Subjects -- Araujo examined the cases of two subjects. The first subject was a 30-year-old woman presented for prenatal care at 12 to 14 weeks gestation. Her medical history was unremarkable, and she had no family history of genetic diseases. She was a fitness enthusiast and adhered to a weight-training program. She was concerned about the effects of exercise on her pregnancy.

The second subject was a 21-year-old woman presented for prenatal care at approximately 10 weeks gestation. Her medical history was unremarkable. She was a varsity college basketball player and expressed her wishes to continue to play competitively, but also was concerned about the well being of her unborn child.

Protocol -- Araujo looked at each case individually, and examined the changes during pregnancy, the physiologic issues, and medical guidelines in order to present the results, which were basically a list of tips for pregnant women regarding exercise. For the individual cases, the women's lifestyles and medical histories were taken into account before recommending an exercise program.

Instrumentation -- Not Applicable.

Training Program -- It was recommended that the first subject reduce the intensity and duration of her exercise routine as she approached 20 weeks gestation. It was also recommended that she continue to reduce the intensity of her workouts and eliminate the abdominal exercises, as well as maintain fluid intake and prevent overheating throughout her pregnancy.

The second subject was warned about the risk of abdominal trauma if she continued to play basketball, as well as the difficulty she would encounter with balance and coordination as time went on. She chose to withdraw from competitive athletics during her pregnancy.

Results -- The first subject's pregnancy was uneventful and resulted in a 20-lb weight gain. A healthy boy was delivered vaginally after approximately 5 hours of labor. The second subject's pregnancy was also uneventful, although little is known about her delivery, as she changed providers and delivered at a different hospital.

Conclusion -- According to Araujo, "Physiologic changes occur in the cardiovascular, respiratory, musculoskeletal, and gastrointestinal system and affect the maternal response to exercise. The anatomic changes of pregnancy alter balance, flexibility, and coordination." For this reason, women must be aware of the need to alter their exercise routines during pregnancy. Many women seek counseling because of these concerns.

Araujo also stresses the fact that athletic women who become pregnant are concerned that exercise may harm their unborn children. According to Araujo, "well-conducted double-blind trials of exercise during pregnancy are rare because of the ethical concerns inherent in asking pregnant women to engage in activities with unknown effects on their unborn children. Most recommendations that physicians make regarding exercise during pregnancy are based on extrapolation of the results of animal studies or on empirical observations of pregnant athletic women." Still, extensive exercise poses great risks to pregnant women, as their bodies need different types of nutrition, and are unable to handle the stress of exercise, including certain types of body position and trauma.

According to Araujo, "Exercise during pregnancy remains a somewhat controversial issue that has not been addressed by well-conducted double-blind studies. Recommendations for the trained athlete usually involve a modification of the type and intensity of exercise to avoid dehydration, hypovolemia, hypotension, and potential trauma to the developing fetus." Therefore, it is important that pregnant women be informed of the potential risks and effects of exercise so that she can make an informed decision about her exercise routine.

Article #2

Reference and Purpose of Study -- This article describes the results of a research project that studied the effect of the health and fitness of pregnant women at the onset of gestation on the course and outcome of the pregnancy.

Methods -- Whether pregnancy reduces 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 influences fitness, were determined in a study of 23 women at the beginning of the second trimester.

Subjects -- The subjects were 23 women who were at the beginning of their second trimester of pregnancy.

Protocol -- Patients were randomly assigned to either a non-exercising or an exercising group. All of the women completed a maximal progressive exercise test on a cycle ergometer at 20 weeks and 30 weeks, during which time pulmonary parameters or aerobic capacity were monitored.

Instrumentation -- Cycle ergometer.

Training program -- Progressive exercise program.

Results -- The exercising women demonstrated greater improvement in aerobic capacity than the non-exercising women, which was evident by increases in tidal volume and oxygen consumption and a stable ventilatory equivalent for oxygen. Pregnancy did not decrease the maximal oxygen consumption between the second and third trimesters, during which detraining could have been substantial.

Conclusion -- Basically, this study suggests that exercise has a positive effect on pregnancy. Interestingly, none of the subjects in this study was previously trained and the average baseline oxygen consumption was in the low range for both groups. However, when placed in a monitored exercise program, the exercise group improved their fitness, as shown by increased maximal oxygen consumption per kilogram of body weight. This study shows that exercise is beneficial to all women.

Article #3

Reference and Purpose of Study -- In a study authored by Thomas Wang and Barbara Apgar, the effect of exercise on pregnancy was studied from a safety point-of-view. The authors looked at theoretic concerns regarding various forms of exercise during pregnancy in an attempt to determine if there is greater sense of well-being, shorter labor and fewer obstetric interventions in physically well-conditioned women as compared with other women.

Methods -- The study determined the effects of exercise on pregnancy by reviewing the theoretic concerns associated with exercise during pregnancy, as well as examining the results of existing clinical trials.

Subjects -- Various women involved in existing clinical studies.

Protocol-- This research article acknowledged the benefits of regular exercise for women who are not pregnant, pointing out the theoretic concerns that exist regarding the effects of exercise on pregnant women. According to the authors of the study, "objective data on the impact of exercise on the mother, the fetus and the course of pregnancy are limited, and results of the few studies in humans are often equivocal or contradictory." Therefore, the authors used existing data to come to a conclusion regarding the effects of exercise on pregnancy.

Instrumentation -- This study examined existing studies on the physiologic changes of pregnancy, the impact of exercise on pregnancy, and labor and outcome.

Training Program -- Not Applicable.

Results -- According to the authors of this study, the physiologic relationship between pregnancy and exercise are still not fully understood. However, while there are theoretic concerns remain about exercise in pregnancy, existing data suggests that exercise during pregnancy is more beneficial than harmful. Still, the study reveals major deficits in our knowledge. For example, the outcomes of racquet and ball sports during pregnancy have not been researched. In addition, many of the reported studies have involved women in middle to upper socioeconomic groups, so the studies are not representative of all groups.

Still, many studies suggested that there might be benefits associated with exercising during pregnancy. For example, some studies reveal a trend toward shorter labor and less need for intervention in well-conditioned and highly trained women.

Conclusion -- Whether exercise is harmful or whether it improves the course and outcome of pregnancy is still very much unknown. Therefore, no definitive recommendation was made in this article to promote exercise during pregnancy. However, the authors conclude that they were unable to find a solid reason that most women cannot continue with exercise during pregnancy and enjoy the possible benefits of improvement in well-being.

Article #4

Reference and Purpose of the Study -- In a journal article by M. Kramer (2002), the author examines the effects of advising healthy pregnant women to participate in regular aerobic exercise on physical fitness, labor and delivery, and the outcome of pregnancy.

Methods -- Physiological responses of the fetus to single, brief bouts of maternal exercise have been reported; suggesting that exercise during pregnancy might have beneficial or adverse effects on pregnancy outcome. This study examined existing reports and field research to determine the outcomes.

Subjects -- Ten trials involving 688 women were included. The subjects were selected based on acceptably controlled comparisons of prescribed aerobic exercise programs.

Protocol -- The Cochrane Pregnancy and Childbirth Group trials register was searched and researchers in the field were surveyed.

Instrumentation-- Trial quality and extracted data were analyzed for this study. Study authors were also interviewed.

Training Program -- Not Applicable.

Results -- The ten trials were not of high methodologic quality. Five trials suggested significant improvement in physical fitness in the exercise group, although differences in measures used to assess fitness did not allow for a quantitative pooling of results. Six trials reported on pregnancy outcomes. According to the Cochrane Library, the authors, "A statistically significant increased risk of preterm birth (relative risk (RR) = 2.29 [95% confidence interval 1.02 to 5.13]) in the exercise group is inconsistent with the absence of effect on mean gestational age [+0.0 (-0.4 to +0.4) weeks] and may have been biased by post-randomization exclusion of women with preterm labor. Results bearing on fetal growth (birth weight, length, and head circumference) were highly variable. One trial found improvements among exercising women in several aspects of self-reported body image, including muscle strength, energy level, and body build."

Conclusions-- Regular aerobic exercise during pregnancy appears to be beneficial in improving physical fitness and body image. However, important risks or benefits for the mother or infant were neither proved nor disproved.

Article #5

Reference and Purpose of study -- In a study published by American Journal of Obstetrics and Gynecology (2002), the benefits of regular exercise during pregnancy are examined, with a particular emphasis on the intensity and timing of an exercise regimen.

Methods -- Comparison of women who exercised lightly, moderately and heavily during the pregnancies.

Subjects -- 75 women who exercised regularly.

Protocol-- The study examined a group of women who exercised regularly to one of three aerobic exercise programs. The researchers examined the results of women who exercised at the same rate throughout the pregnancy in comparison to those who boosted the intensity of their exercise routine later in the pregnancy.

Instrumentation -- Monitoring of women on the treadmill, step aerobic and stair climber.

Training Program-- Women in the first group performed 20 minutes of aerobic exercise five days a week, and increased the duration to 60 minutes by the 24th week of pregnancy until their delivery. Women in the second group exercised for 60 minutes five days a week through week 20, and then decreased the duration to 20 minutes from week 24 until the end of the pregnancy. Women in the third group exercised for 40 minutes for five days a week throughout their pregnancy.

Results -- This research project revealed that none of the babies born to women who exercised moderately or intensely through the ninth month were considered low birth weight. Pregnant women who exercised intensely in the middle or late stages of pregnancy gave birth to babies that were significantly lighter and had less body fat than infants born to the moderate exercisers. However, none of the infants were small enough to be at risk for medical or developmental problems.