| Exercise During Pregnancy Leads
To Healthier Moms And Babies
Studies have shown that exercise has a positive effect on mothers-to-be,
and no detrimental impact on their developing offspring. A new
study further extends the knowledge of research in this area and
has found that not only do women benefit from exercise
in pregnancy, but their fetuses do too.
The researchers hypothesized that maternal exercise during pregnancy
can have a beneficial effect on fetal cardiac programming by reducing
fetal heart rate and increasing heart rate variability. As a result,
a key component of the research involved magnetocardiography (MCG),
the magnetic correlate of an electrocardiogram (ECG). MCG is a
safe, non-invasive method to record the magnetic field surrounding
the electrical currents generated by the fetal heart and nervous
system. In addition to measures of heart rate and variability,
the MCG allows for the study of the cardiac waveforms to measure
of cardiac time intervals.
For the study, fetal recordings were obtained from 24 weeks to
term. Maternal and fetal events were recorded in real time. Fetal
movements such as breathing, body and mouth movements were recorded
using the MCG in order to determine fetal state and to track heart
rate accelerations. The recordings were done at four-week
intervals. The data were derived from fetal MCG conducted in the
second and third trimesters of pregnancy and in the postnatal
period. The data captured was used to measure fetal heart rate
(HR) as derived from the fetal MCG recordings.
Ten women participated in the study. Each was classified as either
an exerciser (n=5) or control (n=5). The women were grouped according
to the frequency, intensity, and length of physical activity they
engaged in (i.e., moderate-to-heavy intensity aerobic activity
for 30 minutes per session three times per week or the metabolic
- there were significantly lower heart rates among fetuses that
had been exposed to maternal exercise. The heart rates among
non-exposed fetuses were higher, regardless of the fetal activity
or the gestational age.
- at each stage of gestation the differences between the fetal
heart rates of the two groups were statistically significant
(p<0.05 using a t-test with equal variances).
- the analysis of short- and long-term heart variability at
28, 32 and 36 weeks of gestation in exercise-exposed vs. non-exercise-exposed
fetuses were statistically different at 32 wks. This trend
is still seen at 36 wks, however it is not significant.
According to Dr. May, “This study suggests that a mother
who exercises may not only be imparting health benefits to her
own heart, but to her developing baby’s heart as well. As
a result of this pilot study, we plan to continue the study to
include more pregnant women.”