13: Is a universal midtrimester transvaginal cervical length assessment program associated with a reduced preterm birth rate?


      To examine whether the introduction of a universal midtrimester transvaginal cervical length (TV CL) assessment program is associated with a reduction in the preterm birth (PTB) rate in low-risk women.

      Study Design

      This is a retrospective cohort study of low-risk women (nulliparas or multiparas with singleton gestations and without any prior PTB) who had a midtrimester sonogram and delivered at a single tertiary institution from January 2007- January 2014. In July 2011, a universal screening program was implemented in which all pregnant women having a sonogram between 18 and 24 weeks of gestation received a routine TV CL measurement. The PTB rates prior to and after the universal assessment were compared. Bivariable analyses were performed, and multivariable analysis was used to identify whether the universal TV CL program was independently associated with a change in the frequency of PTB.


      Of 64,188 eligible women, 46,598 underwent a sonogram prior to the universal TV CL program and 17,590 underwent a sonogram with routine CL assessment after implementation of the program. Of those who underwent screening, 157 (0.89%) had a TV CL measurement of <25 mm. Women who were examined after the TV CL program were more likely to be of white race, have a higher mean body mass index, have a history of a cervical excision procedure, and have chronic hypertension; they were less likely to be cigarette smokers or have pre-gestational diabetes. The introduction of the TV CL program was associated with a significant decrease in the frequency of PTB at less than 37 weeks of gestation, less than 34 weeks of gestation, and less than 32 weeks of gestation (Table). These differences persisted after adjusting for confounders in multivariable regression, and were due to a change in spontaneous (and not medically-indicated) PTB (Table).


      The introduction of a universal TV CL asssessment program in women without a history of prior preterm birth was associated with a reduced risk of PTB.
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