Cervical length in normal pregnancy as measured by transvaginal sonography

Abstract

Cervical length may have potential use as a predictor of preterm delivery [1,2] and diagnosis of cervical incompetence. To determine the risk of preterm delivery or outcome of cervical incompetence, a normogram of cervical length for each period of pregnancy is essential. The objective of this longitudinal study is to determine the cervical length in normal pregnancy as measured by transvaginal sonography. This study was undertaken at Maharaj Nakorn Chiang Mai Hospital, Chiang Mai University Thailand, from 1 March 1992 to 30 September 1996. The subjects met the following inclusion criteria: (1) gestational age between 14 and 40 weeks; (2) history of regular menstruation and knowledge of the exact dates of the last menstruation; (3) singleton pregnancy without medical or