Breathing tests: a measure of the regulation of the maternal cardiovascular activity during pregnancy.

ABSTRACT

The study was the response to breathing test in 30 healthy pregnant volunteers in 20th to 29th weeks of singleton pregnancy with a mean of 25.2 gestational weeks. Deep breathing difference (DBD) was similar in both the groups. The heart rate variability was significantly lower in the second trimester of pregnancy reflected by the smaller standard deviation of R-R interval (SD R-R) during the quiet breathing test.