In the subgroups of women with previous cervical surgery and history of previous preterm birth, cervical shortening was significantly more prominent.

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First-trimester cervical length measurement can predict preterm delivery.

Prematurity remains a leading cause of death and disability, more so actually than chromosomal and structural abnormalities.1,2 The financial impact of preterm birth in health care systems is also a cause of concern globally.

Measurement of cervical length by transvaginal sonography in the late second trimester has proved to be an effective method of prediction.3–5 In addition, evidence from 2 randomized trials suggests that the prophylactic administration of progesterone in women with short cervices reduces the risk of preterm delivery by about 40%.6,7 Few studies have focused on the cervix in the first trimester and the physiologic changes that occur from the end of the first to the second trimester of the pregnancy.8–11 So far, the literature has not been supportive regarding the value of first-trimester cervical length measurement in the prediction of preterm delivery.9–12 Recently a study measuring cervical length at the 11- to 14-week sonographic examination, which focused particularly on the endocervical mucosa, reported promising results.13 In addition, we have reported that first-trimester cervical length alone and in conjunction with the maternal history can predict a short cervix in the second trimester.14 In this study, we longitudinally examined a large cohort of pregnant women from 11 to 24 gestational weeks, and we provide information on physiologic changes in cervical length.

Objectives—The purpose of this study was to examine the evolution of cervical length from the first to second trimester of pregnancy and the value of first-trimester cervical measurement in the prediction of preterm delivery.

Results—Eight hundred singleton pregnancies were studied. The median cervical lengths were 33 mm for Cx1 and 31 mm for Cx2 and Cx3.