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Fetal heart rate pattern interpretation in the second stage of labor using the five‐tier classification: Impact of the degree and duration on severe fetal acidosis
Author(s) -
Ikeda Sayako,
Okazaki Atsuko,
Miyazaki Ken,
Kihira Kana,
Furuhashi Madoka
Publication year - 2014
Publication title -
journal of obstetrics and gynaecology research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.597
H-Index - 50
eISSN - 1447-0756
pISSN - 1341-8076
DOI - 10.1111/jog.12343
Subject(s) - medicine , fetus , fetal heart rate , acidosis , cephalic presentation , umbilical artery , gestational age , obstetrics , metabolic acidosis , pregnancy , heart rate , blood pressure , genetics , biology
Aim The aim of this study was to clarify the association between fetal heart rate ( FHR ) tracing interpretation levels in the second stage of labor and poor fetal acid‐base balance. Material and Methods The database at one tertiary hospital in N agoya, J apan, was retrospectively reviewed for women with singleton fetuses in cephalic presentation and vaginal labor at ≥37 + 0 gestational weeks between 1 J une 2011 and 30 A pril 2012. Continuous FHR tracings in the second stage of labor were subdivided into 15‐min intervals, each of which we called a window, from the beginning of labor through delivery, and were assessed according to the five‐tier classification proposed by the J apan S ociety of O bstetrics and G ynecology, in which level 1 is normal, level 2 is subnormal, and levels 3–5 are abnormal patterns. Results In total, 777 parturient women were eligible for the study protocol. The numbers of women with maximal levels of 1, 2, 3, 4, and 5 were 3, 77, 341, 349, and 7, respectively. No cases of severe fetal acidosis ( pH < 7.0 or base excess <−12 mmol/L) were recorded when the maximal levels were below 3. Both the pH and base excess of the umbilical artery decreased with higher levels of FHR tracings interpretation ( P < 0.001). Both the summations of level‐4 windows and level‐3 and level‐4 windows were significantly higher in women with severe fetal acidosis than in women without ( P < 0.001), indicating that the duration of abnormal levels is associated with severe fetal acidosis. Conclusions Both the degree and duration of FHR tracing abnormalities correlate with severe fetal acidosis.