Department of Obstetrics, Gynecology, and Reproductive Sciences, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania.
Obstet Gynecol. 2013 Oct;122(4):858-862. doi: 10.1097/AOG.0b013e3182a2dccd.
To understand the relationship between cervical length and the risk of prematurity in parous women without a history of preterm delivery.
Data from 2,998 singleton pregnancies enrolled in a multicenter, observational cohort study were analyzed. We subgrouped the population into the following categories: those with history of at least one spontaneous preterm birth (n=467); nulliparous (n=1,237); and parous with a history of at least one term birth and no previous preterm birth (low-risk history group, n=1,284). The relationship between cervical length (measured between 22 and 24 6/7 weeks of gestation) and preterm birth was examined using logistic regression [corrected].Assuming a 40% risk reduction with the use of vaginal progesterone, we calculated the number needed to screen to prevent one preterm birth.
An inverse relationship between cervical length and risk of preterm birth was demonstrated for each subgroup. A short cervix (15 mm or less) was identified in only 0.93% of the low-risk group participants compared with 3.4% of the previous preterm birth group participants and 2.1% of nulliparous women. The overall rate of preterm birth was lowest (10.5%) in the low-risk history group; however, the rate of preterm birth for these women with a short cervix was 25%. For a cervical length cutoff of 15 mm or less, preventing one spontaneous delivery before 34 weeks of gestation would require screening 167 (95% confidence interval [CI] 112-317) women with a previous preterm birth, 344 (95% CI 249-555) nulliparous women, and 1,075 (95% CI 667-2,500) women at low risk.
Although ultrasonographic short cervix is a risk factor for preterm birth among parous women with exclusively term births, the incidence of a short cervix is very low. The number needed to screen to prevent one preterm birth is considerably greater for women who have a low-risk obstetric history.
: II.
了解有既往足月分娩史的经产妇宫颈长度与早产风险的关系。
分析了一项多中心观察性队列研究中 2998 例单胎妊娠的数据。我们将人群分为以下几类：至少有一次自发性早产史（n=467）；初产妇（n=1237）；有既往足月分娩史且无既往早产史的经产妇（低危史组，n=1284）。使用逻辑回归[校正]检查宫颈长度（在 22 至 24 6/7 孕周之间测量）与早产之间的关系。假设阴道用黄体酮可降低 40%的早产风险，我们计算了预防一次早产所需的筛查人数。
每个亚组均显示宫颈长度与早产风险呈反比关系。低危史组参与者中仅 0.93%存在短宫颈（<15 mm），而既往早产组参与者中为 3.4%，初产妇中为 2.1%。低危史组的早产总发生率最低（10.5%）；然而，这些短宫颈的女性早产率为 25%。对于宫颈长度<15 mm 的截断值，为预防 1 例 34 周前自发性分娩，需要对既往有自发性早产的 167 名（95%可信区间 [CI] 112-317）妇女、344 名初产妇（95%CI 249-555）和 1075 名低危史妇女（95%CI 667-2500）进行筛查。
虽然经产妇中仅存在足月分娩史时超声检查发现的短宫颈是早产的危险因素，但短宫颈的发生率非常低。对于有低危产科史的女性，预防一次早产所需的筛查人数明显更多。
II。
