Uterine electrical activity at labor: is there a correlation between labor stages?
OBJECTIVE
To determine the association between the myometrial electrical activity in the active and second stages of labor at term using electrical uterine myography (EUM).


METHODS
A prospective observational study of 47 singleton deliveries at term in a tertiary hospital. All women were assessed using noninvasive 9-channel surface electrodes of the EUM during labor. EUM index (EUMi) was calculated as the mean electrical activity during a 30 min monitoring period and expressed as microjouls (MJ). Mean EUMi of the active and second stages of labor were compared accordingly.


RESULTS
Mean EUMi during the active phase was 3.53 ± 0.43 MJ, whereas mean EUMi in the second stage was 3.66 ± 0.48 MJ (p = 0.02). Correlation analysis between mean EUMi of the active and second stages of labor produced r2=0.68 (p < 0.01). In a regression analysis model EUMi of the active stage of labor remained strongly correlated with the duration of the second stage (r2=0.73, p < 0.001). No correlation was found between EUMi and the duration of the second stage.


CONCLUSIONS
A positive correlation of myometrial electrical activity exists between active phase and second stage of labor. However, while EUMi was associated with the duration of the active phase, no correlation was found between EUMi and the duration of the second stage.
a Helen Schneider Hospital for Women, Rabin Medical Center , Petach Tikva , Israel.|b Sackler Faculty of Medicine, Tel Aviv University , Tel Aviv , Israel.
Liran
L
Hiersch
a Helen Schneider Hospital for Women, Rabin Medical Center , Petach Tikva , Israel.|b Sackler Faculty of Medicine, Tel Aviv University , Tel Aviv , Israel.
Liat
L
Salzer
b Sackler Faculty of Medicine, Tel Aviv University , Tel Aviv , Israel.|c Lis Maternity Hospital, Tel Aviv Sourasky Medical Center , Tel Aviv , Israel.
Amir
A
Aviram
a Helen Schneider Hospital for Women, Rabin Medical Center , Petach Tikva , Israel.|b Sackler Faculty of Medicine, Tel Aviv University , Tel Aviv , Israel.
Eran
E
Hadar
b Sackler Faculty of Medicine, Tel Aviv University , Tel Aviv , Israel.|c Lis Maternity Hospital, Tel Aviv Sourasky Medical Center , Tel Aviv , Israel.
Yariv
Y
Yogev
b Sackler Faculty of Medicine, Tel Aviv University , Tel Aviv , Israel.|c Lis Maternity Hospital, Tel Aviv Sourasky Medical Center , Tel Aviv , Israel.
Eran
E
Ashwal
D000328:Adult; D004576:Electromyography; D005260:Female; D006801:Humans; D007748:Labor Stage, Second / Q000502:physiology*; D011247:Pregnancy; D011446:Prospective Studies; D014590:Uterine Contraction / Q000502:physiology*
Uterine electrical activity; active phase; electronic uterine myography; second stage