Nearly two-thirds of preterm births are spontaneous, often
resulting from either the early stat of labour or preterm premature rupture of
membranes (PPROM). The remaining one-third of preterm births are induced due to
maternal or foetal complications. Preterm labour can occur at various
gestational ages and through different mechanisms. While term labour is
initiated by physiological activation of the labour pathways, preterm labour is
often triggered by pathological factors that activate one or more components of
the same pathway. The pathway, which involves uterine contractions, cervical
dilation, and membrane activation, is consistent across both term and preterm
labour.

Identifying women at risk for preterm labour early is very
crucial, particularly due to the recent increase in preterm births. While
advancements in neonatal care have improved survival rates for very premature
infants, early detection of preterm birth risk remains essential. Therefore,
developing a very sensitive approach to diagnose women at high risk and
implementing effective prevention strategies for preterm labour is of paramount
importance.

Cervical length measurement is considered the gold standard
for detecting preterm birth risk. Since eighties (1980), transvaginal
ultrasonography (TVU) has been used to measure length of cervix, offering a
simple, non-invasive, and accessible tool for identifying pregnant women at
high risk for PTD. TVU can be integrated with routine nuchal translucency (NT)
and anomaly scans to enhance early detection. In some cases, early recognition
of a shortened cervical length can lead to interventions that may reduce the
likelihood of PTB.

Research has shown that using 17αhydroxyprogesterone
caproate, micronized progesterone, and cervical cerclage can help prevent
preterm birth. Measuring cervical length during the first trimester NT scan (10
to 14 weeks) and repeating the measurement during the second trimester anomaly
scan (20 to 24 weeks) while monitoring the rate of shortening is a valuable
indicator for predicting PTL. Although no statistically significant difference
in cervical lengths between term and non-term pregnancies has been observed
during TVS at 10 to 14 weeks, this method provides a useful baseline for
monitoring.

The predictive accuracy for spontaneous preterm delivery
varies based on factors such as the number of foetuses, gestational age during
testing, cervical length, and the presence of preterm birth risk factors. While
a short cervical length is associated with preterm delivery, it remains unclear
whether this condition is a cause or a consequence of pathophysiological
processes.

A prospective cohort design was employed, involving 70
asymptomatic pregnant women aged 18-35 with singleton pregnancies, cervical
lengths >25 mm, and no history of cervical issues. Length of cervix was
measured using TVS at 10-14 weeks and 20-24 weeks of gestation and pregnancy
outcome was noted. Regression models were used to analyse the relationship
between preterm labour and cervical length changes.

The study found that preterm labour occurred in 30% of
patients, predominantly in those with cervical lengths under 26 mm during the
second measurement. Significant differences in cervical length were observed
between pregnancies under and over 37 weeks. Cervical length measurement
demonstrated a specificity of 90.91% and a sensitivity of 76.19% in predicting
preterm labour.

This study’s results highlight the significance of measuring
cervical length as a predictor of premature labour. The statistics showed that
most patients were between the ages of 26 and 30, which is a crucial
reproductive period. The even distribution between first-time mothers (PRIMI)
and those with previous pregnancies (MULTI) suggests that parity alone is not a
significant predictor of preterm labour within this sample. The gestational age
measurements at 10 and 20 weeks provide key insights into common periods for
evaluating cervical length changes. Notably, preterm labour was significantly
associated with shorter cervical lengths, particularly those less than 26 mm
during the second measurement. Consistent with previous research, this data
confirms that shorter cervical lengths raise the likelihood of premature
delivery.

This study highlights the significant association between
cervical length and the risk of preterm labour. Notably, 30% of the patients
experienced preterm labour, predominantly among those with a length of cervix
less than 26 mm during the second assessment. Length of cervix emerged as a
strong predictor of preterm labor, with significant differences observed
between pregnancies that lasted less than 37 weeks and those that exceeded this
gestational period. Patients who delivered before 37 weeks had a shorter
cervical length, with more substantial mean rate and absolute changes,
emphasizing the dynamic nature of cervical shortening as a risk factor for
preterm labour. Vaginal delivery was the predominant mode of birth, followed by
caesarean sections (LSCS). The high sensitivity and specificity of cervical length
measurements underscore their effectiveness as a predictive tool in managing
pregnancy outcomes.

Overall, the findings support the importance of cervical
length evaluation in prenatal care, especially for identifying and managing the
risk of preterm labour. Shorter cervical lengths were consistently associated
with higher risks of early delivery, reinforcing the need for regular
monitoring. Implementing standardized cervical length assessments could
significantly improve early detection and intervention strategies, ultimately
enhancing maternal and neonatal health outcomes.

Source: Gopalan et al. / Indian Journal of Obstetrics and
Gynecology Research 2025;12(3):427–431