Bronson Women's Services in Kalamazoo, Michigan, USA.
J Midwifery Womens Health. 2012 Jul;57 Suppl 1:S12-8. doi: 10.1111/j.1542-2011.2012.00210.x.
Premature shortening of the cervix, or short cervix, is the most predictive risk factor for preterm birth. Results of clinical studies of interventions to prevent preterm birth have shown that identifying at-risk women on the basis of cervical length versus obstetric history alone improves the likelihood of timely interventions with cervical cerclage or progesterone supplementation, improving outcomes. Debate continues over the use of cerclage; however, results of a meta-analysis of randomized controlled trials provide evidence to support its use in women who have history of prior preterm birth and who develop short cervix before 24 weeks' gestation. Results of the recent PREGNANT trial, consistent with the earlier Fetal Medicine Foundation study, support the use of vaginal progesterone for prevention of preterm birth. In women identified by transvaginal ultrasound to have short cervix (10-20 mm) in midtrimester, daily vaginal progesterone gel reduced the risk of preterm birth before 33 weeks' gestation by 45% and before 28 weeks' gestation by 50%. Occurrence of any morbidity and mortality event also was significantly reduced by 43%, with a 61% reduction in the rate of respiratory distress syndrome in infants born to women receiving vaginal progesterone gel versus those receiving placebo. The safety profile of progesterone treatment in early pregnancy is well established, and studies of vaginal progesterone for prevention of preterm birth have identified no additional safety issues. Adverse events were comparable between women receiving progesterone and those receiving placebo. Recent guidelines issued by the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine recommend vaginal progesterone in women with no prior spontaneous preterm birth and cervical length of 20 mm or less at 24 weeks' gestation or earlier. Future studies will refine strategies for prevention of preterm birth to address other risk factors and determine the role of other interventions.
宫颈过短，即宫颈过早缩短，是预测早产的最具预测性的风险因素。预防早产的临床研究结果表明，根据宫颈长度而非产科史来识别高危妇女，可以提高及时进行宫颈环扎术或孕激素补充治疗的可能性，从而改善结局。关于环扎术的使用仍存在争议；然而，一项随机对照试验的荟萃分析结果提供了证据支持在有早产史且妊娠 24 周前出现宫颈过短的妇女中使用环扎术。最近的 PREGNANT 试验结果与早期胎儿医学基金会的研究一致，支持使用阴道孕激素预防早产。在经阴道超声检查发现中孕期宫颈过短（10-20mm）的妇女中，每日阴道用孕激素凝胶可使 33 周前早产的风险降低 45%，28 周前早产的风险降低 50%。任何发病率和死亡率事件的发生也显著降低了 43%，接受阴道用孕激素凝胶治疗的妇女所生婴儿的呼吸窘迫综合征发生率降低了 61%，而安慰剂组则降低了 61%。孕激素治疗在早孕时的安全性已得到充分确立，并且阴道用孕激素预防早产的研究没有发现其他安全性问题。接受孕激素治疗的妇女与接受安慰剂治疗的妇女的不良事件发生率相当。最近美国妇产科医师学会和母胎医学学会发布的指南建议，对于无自发性早产史且妊娠 24 周或更早时宫颈长度为 20mm 或更短时，使用阴道用孕激素。未来的研究将进一步完善预防早产的策略，以解决其他风险因素，并确定其他干预措施的作用。
