Introduction
Prematurity is the leading cause of neonatal morbidity and mortality1, with severe emotional sequelae and high economic
costs. Nowadays, the Preterm Birth (PTB) rate is 10.6% worldwide and
11.2% in Brazil, higher than suggested by the World Health Organization2,3. There are 15 million PTBs each year and the
burden is directly associated with gestational age at birth.
To prevent PTB bad outcomes, studies have focused on identifiable risk
factors such as having a short cervix. Early uterine cervical shortening
in the second trimester is an important risk factor for prematurity4 and is associated with spontaneous preterm birth
(sPTB). Thus, cervical length (CL) measurement during the second
trimester could be used as a tool to identify women at risk of premature
delivery 5.
Transvaginal ultrasound (TVU) performed during the second trimester can
evaluate cervical shortening before labor and then a universal screening
test has been proposed 6. Nevertheless, the CL cutoff
point related to PTB is still in debate. Most studies consider CL ≤25mm
as a risk factor, whereas others consider higher or lower cutoff points7–9.
Predicting PTB among pregnant women is the key to preventive
interventions10. Thus, the aim of this study is to
identify the association between CL at 18–22(+6) weeks of pregnancy and
gestational age at birth in asymptomatic Brazilian women with singleton
pregnancy and to assess the performance of TVU as a screening test to
predict PTB.