a.予定日超過(予定日以後の)妊娠の取り扱い(3.周産期)

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Postterm pregnancy at 42 weeks or later is universally considered abnormal. Management of pregnancy at 40 and 41 weeks, however, has not gained an universal consensus, although several studies reported better prognosis of labors, fetuses and newborns at the earlier gestation. 1. Induction or expectant management According to the report from the perinatal committee in Japan Society of Obstetrics and Gynecology, labor was electively induced at the majority of hospitals (68.4%) at 41 weeks or later. No pregnancy was managed expectantly at 42 weeks or later at any hospita. According to the questionnaire to the members of American Society of Perinatal Obstetricians, 63% of them elected induction of labor at 41 weeks if the cervix was ripe. Ninety eight% of them induced labor at 42 weeks of gestation with ripe cervix and 58% elected induction even with unripe cervix. Several comparison studies between induction and expectant management were made at 42 weeks and 41 weeks where no consistent results were found. Few reports have been found where the comparison was made before EDC (expected data of confinement, <40 weeks). Retrospective and prospective studies indicated better perinatal outcomes but higher C/S rate by induction before EDC than expectant management. 2. Induction of labor (1) Outcome of induction The higher the Bishop score is, the shorter is the duration of labor. Onco-fetal fibronectine of 60 ng/ml or below in the cervical mucus at 39 weeks implies onset of spontaneous labor at 41 weeks or later in 95% of cases. Maternal serum level of DHA-S and incidence of cases without FBM or 20seconds or longer in duration are reported to be higher in cases of successful induction with shorter duration. Shorter cervical length by ultrasound examination correlated positively with the duration of latent phase of the first stage of labor. (2) Method of cervical ripening Mechanical methods such as manual stripping of the membranes, laminaria, metreurynter, dilapan, and Foley catheter are used popularly in Japan. (3) Method of induction Active management of labor with artificial rupture of the membranes and oxytocin infusion is reported possibly to decrease C-section rate due to dystocia. Effect of epidural anesthesia on labor, especially with the use of active management by oxytocin, is recently reported to be none in terms of C-section rate, neonatal prognosis, duration of labor, and incidence of operative delivery. 3. Expectant management Such tests as NST, CST, Biophysical profile score (BPS), modified BPS (NST+AFI), are usually used for fetal surveillance in expectant management of labor. Comparable fetal death rate was reported by expectant management with the aid of CST and BPS, but false positive rate was lower with BPS. There is a report to show possibility that decrease of fetal heart function appears before decreased AFI and FHR pattern of fetal distress. There seems to be no consensus on the method employed for fetal survaillance. It may be prudent, however, to use modified BPS twice a week at 41 weeks of gestation or later with a backup test of CST. In summary, expectant management after EDC under fetal surveillance seems to be rather popular at present. Cases with ripe cervix can also be safely induced around 40 weeks of gestation. Expectant management until the appearance of finding of fetal jeopardy is not advised so that it may be greatly needed to find ways of an early diagnosis of pathological unripe cervix and its treatment. Also, prospective randomized trial remains to be needed with an uniform method of labor induction in order to gain consensus about indication and optimal timing of induction.
社団法人日本産科婦人科学会の論文
2000-08-01

a.予定日超過(予定日以後の)妊娠の取り扱い(3.周産期)

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