Effects of Supine Exercise on Fetal Heart Rate in the Second and Third Trimesters

Abstract

The effects of a brief period of supine exercise on fetal heart rate (FHR) was studied in 25 healthy, regularly exercising women, 12 in the late second trimester and 13 in the mid third trimester. Although statistically significant increases in maternal mean arterial pressure and pulse occurred, the exercise intensity was mild, with the average percent maximal pulse being 46 +/- 5% and 49 +/- 5% in the second and third trimester groups, respectively. Small increases in FHR were seen in both groups, which were insignificant statistically and physiologically. No patient experienced significant FHR abnormalities as a result of the supine exercise sequence. The findings suggest that pregnant women may continue submaximal supine exercise of short duration into the mid to late third trimester.

Effects of prenatal exercise on fetal heart rate, umbilical and uterine blood flow: a systematic review and meta-analysis

“…1 22 23 25 26 42–47 56 68 75 77 A post hoc sensitivity analysis was performed removing one trial (n=6 women) demonstrating a decrease in FHR of 58 bpm during exercise1; the impact of prenatal exercise on FHR was similar (mean difference (MD)=7.41 bpm; see online supplement figure 1). Four studies could not be included in the pooled analysis due to missing SD,27 78 missing baseline values79 and insufficient figure quality76 (n=57 women; see online supplement tables 1 and 2 for additional details). Two of these studies demonstrated that in response to a single bout of swimming exercise, FHR was increased by a mean of 2.0 bpm27 and 7.0 bpm 78.…”

“…Two of these studies demonstrated that in response to a single bout of swimming exercise, FHR was increased by a mean of 2.0 bpm27 and 7.0 bpm 78. One study demonstrated an increase in FHR by 6 bpm in the second trimester and 9 bpm in the third trimester during 5 min of resistance training exercises 79. We were unable to extract data from a fourth study due to insufficient figure quality; however, the authors reported that FHR did not differ between trimesters at rest and during exercise 76…”

“…Fifty-four studies were included in the pooled analysis (n=1494 women) and showed a mean increase in FHR of 4.05 bpm during acute exercise (95% CI 2.98, 5.12, I 2 =83%, p<0.00001; see figure 3). Eleven studies (n=360 women) could not be included in the pooled analysis due to missing SD,2 27 78 80 81 FHR reported as a range,82–84 missing values,85 unusable metrics (ie, percentage of maximal pulse)79 or data were presented in figures that were not of high enough quality to be extracted digitally76 (see online supplement tables 1 and 2 for additional details). These studies reported an increase (mean increase ranged from 2 to 25 bpm)2 27 78–83 or no change76 84 85 in FHR following exercise.…”

Is supine exercise associated with adverse maternal and fetal outcomes? A systematic review

“…Acute exercise consisted of static exercises (eg, pelvis raised off the floor) held for 5 min (total exercise time 35–40 min),22 abdominal strengthening exercises including pelvic tilts performed for 5 min,19 dynamic floor exercise that included abdominal exercises such as crunches and leg lifts for 10 min,20 and sets of single leg extensions and double leg extensions 23. Intensity (defined as 15 (hard) on the Borg’s Rating of Perceived Exertion 20-point scale) was recorded in only one study 20.…”

“…Fetal outcomes were potentially adverse changes in (5) fetal movements, (6) FHR (patterns and fetal bradycardia FHR <110 bpm19), (7) uterine blood flow, (8) low birth weight (small for gestational age (SGA), <2500 g, <10th/15th percentile for gestational age or intrauterine growth restriction (IUGR)), (9) perinatal mortality (death between 20 weeks’ gestation and 28 days of life), and (10) others (as defined and documented by individual study authors). Examples of abnormal FHR patterns included absent (non-reactive) baseline FHR variability in combination with recurrent late decelerations or recurrent variable decelerations 5 6.…”