Suto Maiko, Takehara Kenji, Misago Chizuru, Matsui Mitsuaki
J Midwifery Womens Health. 2015 Jul-Aug;60(4):419-27. doi: 10.1111/jmwh.12324.
Perineal lacerations during birth can cause ongoing physical, psychological, and social problems. However, the prevalence of lacerations following normal spontaneous vaginal birth in women with low-risk pregnancies is unknown. We investigated the prevalence of perineal lacerations and factors associated with lacerations among low-risk Japanese women who had normal spontaneous vaginal births.
Pregnant women who were cared for between January 1, 2008, and June 30, 2011, in 3 midwife-led birth centers in Tokyo, Japan, where invasive medical interventions are rarely applied, were included. We investigated the prevalence of perineal lacerations and conducted univariate and multivariate analyses on the relationship between the prevalence of lacerations and selected maternal and neonatal characteristics.
A total of 1881 pregnant women had initial antenatal care at one of the 3 study sites. Of these, 1521 were eligible for inclusion. Intact perineum rates were 49.5% (209/422) and 69.9% (768/1099) in nulliparous and multiparous women, respectively. First-degree lacerations occurred in 36.7% (155/422) of nulliparous women and 27.1% (298/1099) of multiparous women, and second-degree lacerations occurred in 13.5% (57/422) of nulliparous women and 3.0% (33/1099) of multiparous women. One multiparous woman experienced a third-degree laceration (0.1%). No women suffered fourth-degree or cervical lacerations. Logistic regression analyses showed that older age (≥ 35 years), the hands-and-knees position, and using a birthing chair during birth increased the risk of perineal laceration both in nulliparous and in multiparous women. In addition, waterbirths increased the risk of perineal laceration in multiparous women.
In normal spontaneous vaginal births among a low-risk population, it is possible to avoid episiotomy and achieve a high rate of intact perineum, with few second-degree and third-degree lacerations.
分娩时的会阴撕裂可导致持续的身体、心理和社会问题。然而，低风险妊娠女性正常自然阴道分娩后撕裂伤的发生率尚不清楚。我们调查了正常自然阴道分娩的低风险日本女性会阴撕裂伤的发生率以及与撕裂伤相关的因素。
纳入2008年1月1日至2011年6月30日期间在日本东京3个由助产士主导的分娩中心接受护理的孕妇，这些分娩中心很少采用侵入性医疗干预措施。我们调查了会阴撕裂伤的发生率，并对撕裂伤发生率与选定的孕产妇和新生儿特征之间的关系进行了单因素和多因素分析。
共有1881名孕妇在3个研究地点之一接受了初次产前护理。其中，1521名符合纳入条件。初产妇和经产妇的会阴完整率分别为49.5%（209/422）和69.9%（768/1099）。初产妇中36.7%（155/422）发生一度撕裂伤，经产妇中27.1%（298/1099）发生一度撕裂伤；初产妇中13.5%（57/422）发生二度撕裂伤，经产妇中3.0%（33/1099）发生二度撕裂伤。一名经产妇发生了三度撕裂伤（0.1%）。没有女性发生四度或宫颈撕裂伤。逻辑回归分析表明，年龄较大（≥35岁）、手膝位以及分娩时使用分娩椅会增加初产妇和经产妇会阴撕裂伤的风险。此外，水中分娩会增加经产妇会阴撕裂伤的风险。
在低风险人群的正常自然阴道分娩中，可以避免会阴切开术，并实现较高的会阴完整率，二度和三度撕裂伤较少。
