分娩第二期における側臥位が母体および新生児の予後に及ぼす影響：傾向スコアマッチング解析を用いた観察研究

This study aims to examine the effects of lateral positions during the second stage of labour on maternal and neonatal outcomes.

A prospective observational study was conducted in three Chinese hospitals from June to November 2020.

Eligible women were divided into groups based on their use of lithotomy or lateral positions during the second stage of labour. Propensity score matching (PSM) was employed to assess the effects of lateral positions on maternal outcomes (perineal tears, episiotomy use, postpartum blood loss, duration of the second stage of labour, and mode of birth) and neonatal outcomes (Apgar scores at one and 5 min postpartum).

After PSM matching, lateral positions were associated with a 21% reduced risk of episiotomy use among primiparous women. Primiparous women adopting lateral positions also had significantly reduced risks of moderate perineal tears. There were no significant differences in the duration of the second stage of labour, mode of birth or rates of blood loss over 500 mL at 2 h postpartum. However, lateral positions increased the duration of the second stage of labour by 10 min among primiparous women who adopted lateral positions in this study, and both primiparous and parous women using lateral positions had greater postpartum blood loss. Cases of Apgar scores less than seven and severe perineal tears were rare.

This prospective observational study indicates that lateral positions during the second stage of labour may offer protective benefits for the perineum among primiparous women. However, their use requires careful clinical judgement, as they may not be suitable for primiparous women experiencing slower labour progress, and additional attention should be given for monitoring postpartum blood loss, regardless of parity.