CAN OBSERVED FETAL BREATHING PREDICT SUCCESSFUL LABOR INDUCTION

Objective: To determine if a quantified incidence of fetal breathing a ctivity, observed continuously for 1 h, can aid in the prediction of s uccessful induction of labor at term. Methods: We enrolled gravidas sc heduled to undergo indicated induction of labor (study group) and non- laboring gravidas of similar gestational age who were allowed subseque ntly to enter spontaneous labor (control group) for observation of fet al breathing activity before the onset of labor. Each group received 1 h of continuous ultrasound observation of fetal breathing movements, acquired and analyzed off line by a validated software program. Based on a previously published threshold of fetal breathing movement incide nce (4%) associated with a spontaneous onset of labor, power analysis (beta = 0.20) required a total minimum enrollment of 24 patients. Main outcome variables included length of labor, the interval to entering spontaneous or induced labor, and success of induction, as defined by entry into active phase of labor. Groups were compared with Student's t test and Chi-square test (P < 0.05, considered significant). Results : Thirty study and 18 control patients had ultrasound observations for fetal breathing movement incidence, rate, and breath interval. The me an incidence of breathing was 24% in the study group and 31% in the co ntrol group. A 4% fetal breathing movement incidence was used to di vi de both groups into ''breathers'' (81% study, 95% control) and ''non-b reathers'' (19% study, 5% control). ''Breather'' and ''non-breather'' subgroups were similar for success of induction, length of labor, and cervical ripening. The induction and control groups were also similar for the other maternal and fetal variables analyzed. Conclusions: Pros pective observation of fetal breathing movement incidence does not imp rove the prediction of the successful outcome of labor induction at te rm.