Cervical length in the mid-trimester is now a well-verified predictor of
preterm birth, for both low-and high-risk women. Furthermore, vaginal
progesterone has been shown to be a safe and beneficial intervention for women
with no risk factors who are diagnosed with a shortened cervical length (<2cm). In
fact, at 24 weeks’ gestation, every 1 mm of additional cervical length equates to a
significant decrease in preterm birth risks (odds ratio, 0.91). However, the use of
cervical measurement did not achieve widespread use until more than a decade
later, when researchers began to identify interventions that could prolong
pregnancy if a short cervix was diagnosed.
The benefits of identifying a short cervix likely extend to women with a
history of prior preterm birth. The possible benefits of diagnosing and intervening
for a shortened cervix have tipped many experts and clinicians toward the practice
of universal cervical length screening of all singleton pregnancies. We estimated that
screening would prevent 248 early preterm births-as well as 22 neonatal deaths or
neonates with long-term neurological deficits-per 100,000 deliveries. Neither the
American College of Obstetricians and Gynecologists and the Society for Maternal-
Fetal Medicine state that this approach may be considered in women with singleton
gestations without prior spontaneous preterm births.