In recent years, perinatal viability has shifted from 24 to 22 weeks of gestation at many institutions after improvements in survival in neonates delivered at the limit of viability. Monitoring these fetuses is essential because antenatal interventions with resuscitation efforts are available for patients at risk of delivery at the limit of viability. However, fetal monitoring using biophysical profiles has not been extensively studied in very preterm pregnancies, particularly in the periviable period (20 weeks 0 days to 23 weeks 6 days). This study aimed to (1) investigate whether the completion of biophysical profiles within 30 minutes is feasible in very preterm pregnancies, and (2) determine the average observation time required to achieve a score of 8 out of 8 in very preterm pregnancies from 20 weeks 0 days to 31 weeks 6 days. This study prospectively evaluated biophysical scores in singleton pregnancies undergoing routine ultrasonography at or near viability from 20 weeks 0 days to 23 weeks 6 days (periviable or group I), 24 weeks 0 days to 27 weeks 6 days (group II), and 28 weeks 0 days to 31 weeks 6 days (group III). The results and duration of biophysical profiles were compared with those of a control group (32 weeks 0 days to 35 weeks 6 days) undergoing indicated fetal surveillance. Biophysical profiles were performed for all studied pregnancies until a score of 8 out of 8 was obtained. When >1 biophysical profile was obtained during pregnancy, each was analyzed individually. Pregnancies with fetal anomalies or obstetrical/medical indications for fetal well-being surveillance were excluded. Analysis of variance and post hoc Tukey tests were used for comparisons. Data were collected for 123 participants, yielding 79, 75, and 72 studies for groups I, II, and III, respectively. The control group included 42 patients, yielding 140 studies. At 30 minutes, 80% (63/79) of the studies in the periviable group had a score of 8 out of 8, as opposed to 100% (140/140) in the control group (<.001). The mean±standard deviation time in minutes to achieve a biophysical score of 8 out of 8 was 23.3±10.1 in the periviable group, as opposed to 9.4±6.5 in controls (<.001). Extending the study to +2 standard deviations (43.6 minutes) in the periviable group resulted in 97% (77/79) of the scans scoring 8 out of 8 in the absence of adverse outcomes. In the other groups, a biophysical score of 8 out of 8 within 30 minutes was obtained in 97% (73/75) and 100% (72/72) in groups II and III, respectively; the mean±standard deviation times were 17.1±8.4 minutes (group II) and 13.1±7.3 minutes (group III). No adverse outcomes developed during the study participation in groups I to III. Biophysical scores of 8 out of 8 can be successfully achieved in low-risk periviable pregnancies (20 weeks 0 days to 23 weeks 6 days) within an observation time longer than the standard 30-minute duration. The time required to reach a score of 8 out of 8 decreases as gestation progresses. We suggest adjusting the observation time for biophysical profile completion according to the gestational age.

中文翻译：

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围产儿和极早产低风险妊娠的生物物理特征持续时间

近年来，随着生存能力极限新生儿生存率的提高，许多机构的围产期生存能力已从妊娠 24 周转变为 22 周。监测这些胎儿至关重要，因为对于处于生存能力极限的分娩风险的患者，可以进行产前干预和复苏努力。然而，使用生物物理特征进行胎儿监测尚未在极早产妊娠中得到广泛研究，特别是在围产期（20 周 0 天至 23 周 6 天）。本研究旨在 (1) 调查在 30 分钟内完成生物物理特征对于极早产妊娠是否可行，以及 (2) 确定极早产妊娠从 20 周起达到 8 分（满分 8 分）所需的平均观察时间0 天至 31 周 6 天。本研究前瞻性评估了单胎妊娠在 20 周 0 天至 23 周 6 天（可存活或组 I）、24 周 0 天至 27 周 6 天（组 II）和 28 周期间接受常规超声检查时处于或接近存活状态的生物物理评分。 0 天至 31 周 6 天（第 III 组）。将生物物理特征的结果和持续时间与接受指定胎儿监测的对照组（32周0天至35周6天）的结果和持续时间进行比较。对所有研究的妊娠进行生物物理分析，直到获得 8 分（满分 8 分）。当在怀孕期间获得>1个生物物理特征时，对每个特征进行单独分析。排除胎儿异常或有胎儿健康监测的产科/医学指征的妊娠。使用方差分析和事后 Tukey 检验进行比较。收集了 123 名参与者的数据，分别为 I、II 和 III 组开展了 79、75 和 72 项研究。对照组包括 42 名患者，产生 140 项研究。 30 分钟时，可存活组中 80% (63/79) 的研究得分为 8 分（满分 8 分），而对照组为 100% (140/140) (<.001)。在可存活组中，达到 8 分（满分 8 分）生物物理评分的平均±标准差时间（以分钟为单位）为 23.3±10.1，而对照组为 9.4±6.5 (<.001)。在可存活组中将研究扩展至+2标准差（43.6分钟），在没有不良结果的情况下，97%（77/79）的扫描得分为8分（满分8分）。在其他组中，第II组和第III组在30分钟内获得生物物理评分为8分（满分8分）的比例分别为97%（73/75）和100%（72/72）；平均±标准差时间为17.1±8.4分钟（组II）和13.1±7.3分钟（组III）。在第一组至第三组的研究参与期间没有出现不良后果。低风险围产期妊娠（20 周 0 天至 23 周 6 天）可以在比标准 30 分钟持续时间长的观察时间内成功获得生物物理评分 8 分（满分 8 分）。随着妊娠的进展，达到 8 分（满分 8 分）所需的时间会减少。我们建议根据胎龄调整完成生物物理概况的观察时间。