Short-term heart rate dynamics of women during labor

We studied 10 minutes segments of heartbeat interval fluctuations from 18 young women in labor with normal outcome of pregnancy. Data of each studied case were classified into two distinct groups. One group involving segments where the uterine activity was observable (three or more contractions in ten minutes), and the other group of reference having segments with fewer uterine activity or not presenting contractions at all. For comparison, we also included segments collected during the last trimester of gestation prior to labor from a third group of women. Corresponding RR interval series were analyzed to estimate RR_mean, RMSSD, α₁, α_1(MAG) and α_1(SIGN) parameters. No significant differences among groups were identified in RMSSD, α₁ and α_1(MAG) Nevertheless, α_1(SIGN) did present significant differences in comparison with the last trimester results (p<;0.007), revealing a subtle change in the temporal organization of maternal RR series during labor. Results of these parameters then suggest that during labor, despite preserving a concomitant non-linear influence, the maternal short-term autonomic cardiac regulation behaves with less antagonism.