Table 1.

Exercise Intensity Recommendations from ACOG, 1985 to 2020.

Year, reference	Background text from ACOG guideline	ACOG recommendation
1985 21	“During normal pregnancy, maternal blood volume increases by about 30% and sometimes more, and heart rate and cardiac output are significantly elevated at rest.” (page 2)	“In general, target heart rates for pregnant and postpartum women should be set approximately 25-30% lower than would be appropriate at other times.” (page 2) “Pregnant and postpartum women who exercise should be advised to measure heart rates during activity and given limits to follow.” (page 2) “Pregnancy only: Maternal heart rate should not exceed 140 beats per minute.” (page 4) “Heart rate should be measured at times of peak activity. Target heart rates and limits established in consultation with the physician should not be exceeded.” (page 4)
1994, Technical Bulliten #189 22	“Conflicting evidence exists concerning maternal heart rate response to steady-state aerobic exercise during pregnancy; both blunted and normal responses to weight-bearing and nonweight-bearing exercise have been reported.68,82” (page 65) “There are no data in humans to indicate that pregnant women should limit exercise intensity and lower target heart rates because of potential adverse effects.” (page 68)	Not mentioned
2002 Committee Opinion #267 23	Not mentioned	Not mentioned
2015 Committee Opinion #650 27	“Blood volume, heart rate, stroke volume, and cardiac output normally increase during pregnancy, while systemic vascular resistance decreases.” (page 3)	“Because blunted and normal heart-rate responses to exercise have been reported in pregnant women, the use of ratings of perceived exertion may be a more effective means to monitor exercise intensity during pregnancy than heart-rate parameters. 83 For moderate-intensity exercise, ratings of perceived exertion should be 13—14 (somewhat hard) on the 6-20 Borg scale of perceived exertion (Table 1 ACOG). Using the “talk test” is another way to measure exertion. As long as a woman can carry on a conversation while exercising, she is likely not overexerting herself. 84 ” (page 4)
2020 ACOG Committee Opinion #804 28	“Blood volume, heart rate, stroke volume, and cardiac output normally increase during pregnancy, and systemic vascular resistance decreases.” (page e179) “Further research is needed on the effects of vigorous intensity exercise in the first and second trimesters and of exercise intensity exceeding 90% of maximal heart rate. 85 ” (page e183)	Quote from 2015 (“because blunted….) repeated on page e182 Intensity of exercise, less than 60-80% of age predicted maximal maternal heart rate, usually not exceeding 140 beats per minute; ratings of perceived exertion 12-14 (Table 3 ACOG)

Abbreviation: ACOG, American College of Obstetricians and Gynecologists