Moroz Leslie A, Brock Clifton O, Govindappagari Shravya, Johnson Denise L, Leopold Beth H, Gyamfi-Bannerman Cynthia
Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY.
Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY.
Am J Obstet Gynecol. 2017 Feb;216(2):159.e1-159.e7. doi: 10.1016/j.ajog.2016.10.002. Epub 2016 Oct 8.
There is a lack of consensus on the optimal transvaginal cervical length for determining risk for spontaneous preterm birth in twin pregnancies. Change in transvaginal cervical length over time may reflect early activation of the parturition process, as has been demonstrated in singleton pregnancies. The association between change in transvaginal cervical length and the risk for spontaneous preterm birth has not yet been described in the population of women with diamniotic twin pregnancies.
Our primary objective is to determine whether rate of change in transvaginal cervical length in the midtrimester is associated with spontaneous preterm birth in twin gestations. Our secondary objective is to describe parameters for identifying patients at increased risk for spontaneous preterm birth based on change in transvaginal cervical length over time.
This is a retrospective cohort of serial transvaginal cervical length performed for twin pregnancies at a single institution from 2008 through 2015. Women with diamniotic twin pregnancies who had transvaginal cervical length measurements at 18 and 22 weeks' gestation and outcome data available were included. Logistic regression was used to determine the relationship between the rate of change in transvaginal cervical length and the risk for the primary outcome of spontaneous preterm birth <35 weeks as well as spontaneous preterm birth <32 weeks.
In all, 527 subjects met inclusion criteria for this study. The average rate of change in transvaginal cervical length for patients with spontaneous preterm birth <35 weeks was -0.21 cm/wk (SD 0.27) vs -0.10 cm/wk (SD 0.24) for patients who delivered ≥35 weeks (P < .01). The rate of change in transvaginal cervical length was associated with spontaneous preterm birth <35 weeks when controlling for initial transvaginal cervical length and other important risk factors for spontaneous preterm birth. Results for spontaneous preterm birth <32 weeks were similar. This association remained significant when the rate of weekly change was treated as a dichotomous variable based on an apparent inflection point in the risk for spontaneous preterm birth: women with rapid change in transvaginal cervical length, ≥-0.2 cm/wk, had 3.45 times the odds of spontaneous preterm birth as those with less rapid change (95% confidence interval, 2.15-5.52) when controlling for initial transvaginal cervical length.
Change in transvaginal cervical length in the midtrimester is associated with spontaneous preterm birth, and therefore protocols for serial transvaginal cervical length measurement can provide the clinician with information to identify at-risk patients. A decrease of ≥0.2 cm/wk of transvaginal cervical length identifies patients at increased risk for spontaneous preterm birth <35 weeks.
对于双胎妊娠中确定自发早产风险的最佳经阴道宫颈长度，目前尚无共识。经阴道宫颈长度随时间的变化可能反映分娩过程的早期激活，这在单胎妊娠中已得到证实。经阴道宫颈长度变化与双绒毛膜双胎妊娠女性自发早产风险之间的关联尚未见报道。
我们的主要目的是确定孕中期经阴道宫颈长度的变化率是否与双胎妊娠的自发早产相关。我们的次要目的是描述基于经阴道宫颈长度随时间的变化来识别自发早产风险增加患者的参数。
这是一项回顾性队列研究，对2008年至2015年在单一机构进行的双胎妊娠系列经阴道宫颈长度测量进行分析。纳入有双绒毛膜双胎妊娠且在妊娠18周和22周有经阴道宫颈长度测量值及结局数据的女性。采用逻辑回归确定经阴道宫颈长度变化率与<35周自发早产以及<32周自发早产这两个主要结局风险之间的关系。
共有527名受试者符合本研究的纳入标准。<35周自发早产患者经阴道宫颈长度的平均变化率为-0.21 cm/周（标准差0.27），而≥35周分娩患者为-0.10 cm/周（标准差0.24）（P<.01）。在控制初始经阴道宫颈长度和其他自发早产重要风险因素后，经阴道宫颈长度变化率与<35周自发早产相关。<32周自发早产的结果相似。当根据自发早产风险的明显转折点将每周变化率视为二分变量时，这种关联仍然显著：经阴道宫颈长度快速变化（≥-0.2 cm/周）的女性，在控制初始经阴道宫颈长度后，自发早产的几率是变化较慢女性的3.45倍（95%置信区间，2.15 - 5.52）。
孕中期经阴道宫颈长度的变化与自发早产相关，因此系列经阴道宫颈长度测量方案可为临床医生提供识别高危患者的信息。经阴道宫颈长度每周减少≥0.2 cm可识别<35周自发早产风险增加的患者。
