A meta-analysis of assessed maternal and fetal responses to exercise in regards to pregnancy and birthing outcomes; possible risks and benefits of exercise during pregnancy; and current recommendations for exercise during pregnancy.
Effect of Maternal Physical Activity on Pregnancy and Birthing Outcomes
Effect of Maternal Physical Activity on
Pregnancy and Birthing Outcomes
Outcome Active women (n =
Inactive women (n =
Birthweight, g 3448 ± 310 3518 ± 418 0.53
First stage of labor,
301 (40–770) 304 (75–555) .87b
Second stage of labor,
88 (9–178) 146 (3–212) .05b
Duration of pushing
50 (4–115) 83 (1–133) .14b
Apgar score (<7 at 5
1 1 0.74
Meconium 12 6 0.77
19 7 0.19
20 15 0.45
hemorrhage (≥500 mL)
6 7 0.32
9 11 0.06
Characteristic Active womena (n = 27) Inactive womenb (n = 17) P value
Age, y 31.5 ± 5.4 30.5 ± 5.8 0.55
Primiparous women, n
19 (70.4) 10 (58.8) 0.52
Height, cm 167.8 ± 6.4 163.2 ± 5.2 0.01
Prepregnancy weight, kg 64.3 ± 13.1 60.8 ± 9.9 0.35
Prepregnancy BMI, kg/m2 22.8 ± 4.2 22.8 ± 3.5 0.98
Weight, kg 79.3 ± 13.4 75.1 ± 11.4 0.88
Body weight gain, kg 15.9 ± 3.8 15.1 ± 4.3 0.51
PAL 1.6 ± 0.1 1.4 ± 0.1 0.001
TEE, kJ/d 12,557 ± 2374 10,508 ± 1751 0.004
AEE, kJ/d 3478 ± 1129 1735 ± 456 0.001
V̇O2max, (mL/min/kg) 34.9 ± 5.6 30.3 ± 6.2 0.01
V̇O2max, (mL/min) 2742 ± 475 2256 ± 484 0.002
Sleeping heart rate, bpm 66.7 ± 7.8 74.6 ± 6.4 0.001
Movement, counts/min 23.5 ± 9.5 13.4 ± 5.6 0.012
TABLE 1. Characteristics of subjects
AEE, activity energy expenditure; BMI, body mass index; PAL, physical activity level; TEE, total energy expenditure; V̇O2max,
maximal oxygen uptake. Melzer. Effects of recommended levels of physical activity on pregnancy outcomes. Am J ObstetGynecol 2010.
a≥30 minutes of moderate physical activity, defined as any activity with an energy expenditure between 3-6 metabolic equivalents
(METS), or multiples of resting metabolic rate;
b<30 minutes of moderate physical activity (METs = 3-6).
TABLE 2. Delivery outcomes
Melzer. Effects of recommended levels of physical activity on pregnancy outcomes. Am J Obstet Gynecol 2010.
a Active women (n = 25) and inactive women (n = 15) who started first stage of labor;
b Means (range) estimated from survival curves (Kaplan-Meier), P value computed from log rank test;
c Active women (n = 24) and inactive women (n = 14) who started second stage of labor.
EXS 304- March 28, 2013
Effect of Maternal Physical Activity on
Pregnancy and Birthing Outcomes
Kimberly Nicole Rooker
✤ Background: Many pregnant women wish to engage in exercise during pregnancy, but are
concerned about possible adverse effects on the outcome of pregnancy. Contrary to
traditionally recommending reducing exercise during pregnancy, doctors are now
recommending light to moderate physical activity throughout pregnancy. Research has
provided new information about how pregnant women and their fetuses respond graded
exercise . Studies have shown possible maternal benefits of exercising during pregnancy to
be improved cardiovascular function [16, 21], improved muscular strength , fewer cesarean
deliveries [7, 21], limited pregnancy weight gain , decreased pregnancy symptoms including
nausea, musculoskeletal discomfort, edema, gestational diabetes and hypertension . Fetal
benefits include decreased fat mass, improved stress tolerance, and advanced neurobehavioral
maturation . Currently, The American College of Obstetricians and Gynecologists generally
recommends at least thirty minutes of exercise on most days, but preferably all days for healthy
women with uncomplicated pregnancies . However these guidelines are not universally
accepted, and many women and doctors are hesitant to start and recommend an exercise
routine due to the insufficient evidence about benefits and risks.
✤ Objectives: To summarize assessed maternal and fetal responses to exercise in regards to
pregnancy and birthing outcomes; possible risks and benefits of exercise during pregnancy;
and current recommendations for exercise during pregnancy.
✤ The Kresge Library Database was the main search engine used by going to library.oakland.edu
and searching the below keywords. Returned search results of interest cited multiple other
studies, which were then specifically searched for through the library’s database by entering the
title of the study, authors, and year published.
✤ Keywords: Pregnancy, exercise, prenatal care, perinatal care, postpartum care, fetal response
to exercise, effect of exercise on gestation age
✤ Selection criteria: Controlled trials and peer-reviewed articles. Types of interventions included
increasing, decreasing, and/or not changing current exercise habits. Aside from inactive
groups, exercise durations ranged from twenty to sixty minutes per session, at various
frequencies, and intensities spanning from low to heavy.
✤ Criteria for exclusion from the summary were studies that examined participants with the
following: irregular medical follow-ups throughout the entire pregnancy, heart disease or
treatment that may alter cardiovascular conditioning, preeclampsia, diabetes, risk for
premature delivery, high probability of cesarean section, fetal malformation, or any other
serious medical condition preventing them from exercising safely.
Methods of Study at Hand-
Melzer K, Schuts Y, Soehnchen N, et al.
✤ The study that was examined in detail evaluated the energy expenditure,
aerobic fitness, and sleeping heart rate of 44 total pregnant women.
Medical records were examined for pregnancy outcome .
✤ Women were split into an active group (n = 27) and an inactive group (n
= 17) after total and activity-related energy expenditure and
cardiovascular fitness measurements were obtained. The active group
did 30 or more minutes of moderate physical activity per day and the
inactive group did less than 30 minutes of moderate physical exercise
per day .
✤ Based on ACOG recommendations, moderate physical activity was
defines as any activity between 3-6 METs .
✤ Active women spent more time on moderate physical activity than the inactive
women (69.1 ± 26.6 vs 16.6 ± 9.2 minutes, respectively; P = 0.001), but no
statistically significant difference in time spent on vigorous activity (>6 METs)
(1.52 ± 3.5 and 0.24 ± 0.6 minutes/day, respectively; P = 0.14) .
✤ As shown in Table 1, the groups had general similar characteristics, except
for height, with the active group being taller (168 cm) than the inactive group
(163 cm) (P = 0.01) .
✤ The activity-related energy expenditure of the active women was twice of that
of the inactive women (3478 kJ/day vs 1735 kJ/day, respectively; P = 0.001)
✤ Compared to inactive women, the higher physical activity level of active
women was associated with significantly higher relative and absolute
VO2max, and significantly lower sleeping heart rate (Table 1) .
✤ As shown in Table 2, between active and inactive women differences
in birthweight, Apgar scores, meconium-stained amniotic fluid, use of
spinal/epidural anesthesia, episiotomy or perineal laceration, and
postpartum hemorrhage were not significant .
✤ Duration of the first stage of labor was similar between the two
groups. Duration of the second stage of labor was shorter in the active
compared to the inactive (88 vs 146 minutes, respectively; P = 0.051)
✤ Association between physical activity and operative delivery, adjusted
for parity, maternal weight gain, and newborn birthweight was
significant (crude OR, 3.67; adjusted OR, 7.65; 95% CI, 1.27-45.84; P
= 0.026) .
✤ As shown in Figure 1.1, four out of eight studies determined lower
mean birth weights among active pregnant women, and the other four
studies exhibited higher mean birth weights among active pregnant
women; however none of these results were statistically significant.
✤ Figure 2.1 depicts the same same eight studies, but is adjusted to
account for the different confidence intervals.
✤ The study examined in this summary shows no adverse effects to the
fetus from light to moderate intensity exercise, which is consistent
with conclusions published in similar studies [3, 4, 7, 9, 11, 21, 23].
Furthermore, this study and several of the studies conclude maternal
exercise benefits the mother and/or the baby [3, 7, 21, 23].
✤ For women with normal pregnancies, thirty minutes or more of
moderate physical activity per day is accompanied by better
cardiovascular fitness, with no negative effects on fetal condition or
outcome of labor and delivery. Furthermore, the study indicates that
the recommended level of physical activity may play a role in
decreasing both the duration of the second stage of labor and the
incidence of operative delivery .
✤ Further studies with larger sample sizes are essential to confirm any
associations between physical activity and pregnancy outcomes .
✤ Overall, still not much is known about exercising during pregnancy for
various reasons including data collection difficulties and participant
compliance and consistency .
✤ This is why the best prescription for exercise during pregnancy is still
believed to be one that is individually dosed. Although there are many
potential benefits, maternal health and fitness level should be assessed
before beginning a regimen.
✤ Currently, The American College of Obstetricians and Gynecologists
generally recommends at least 30 minutes of exercise on most days, but
preferably all days for healthy women with uncomplicated pregnancies
. If the normal, healthy mother is already in a regular exercise regimen
that is more than 30 minutes, then she may continue with that regimen
✤ Universally agreed upon warning signs that one should stop exercising
✤ Vaginal bleeding/ fluid leakage
✤ Chest pain
✤ Uterine contractions
✤ Decreased fetal movement