Recent literature has questioned both the cost-efficiency and the usefulness of cervical length measurement as an indicator of preterm delivery 15, 16, especially in developing nations like Iran 17. In this regard, studies have found that a cervical length below 25 mm at 24 to 28 weeks of gestation can predict preterm birth 18. This study evaluated the relationship between cervical length in the second trimester of pregnancy and gestational age, birth weight, and Apgar scores at delivery.
While ANOVA demonstrated a significant relationship between cervical length classification and gestational age (p=0.031) and birth weight (p=0.001), no significant (p≤0.05) correlation was found between cervical length classification gestational age at birth (p=0.35), and Apgar scores (p=0.29). However, a significant correlation was found with birth weight (p=0.04).
The results of this study showed that the mean cervical length at 18-20 weeks of gestation was 30.94±3.74 mm. While this finding is more than the 31 mm of Melamed et al. 19, it is lower than that of Jafari et al., which demonstrated a mean cervical length of 38.30±7.28 mm at 20 weeks gestation 20. In addition to maternal characteristics, increased stress, psychosocial problems, obesity, aging, smoking, alcohol abuse, underlying diseases, race, nationality, socioeconomic status, number of fetuses, and lack of prenatal care may be contributing factors to this variation 18, 21.
Despite not finding a definitive association between cervical length and Apgar scores, this study demonstrated that cervical sonography has limited potential in predicting gestational age, which is in line with previous research that has indicated that shorter cervical length is associated with preterm birth 22. As Jafari-Dehkordi et al. found, a shorter cervical length from 8-38 weeks of gestation led to an increased likelihood of preterm birth 20.
This study also found that cervical length had a significant impact on infant birth weight, showing that as cervical length increased, so did infant birth weight. These findings are consistent with previous studies 23. This finding is important since low birth weight can result from preterm birth or intrauterine growth restriction (IUGR). This low birth weight, whatever the cause, is strongly associated with fetal and neonatal mortality and morbidity, inhibited growth and cognitive development, mortality risk in the first year and is also associated with an increased risk of developing diseases in adulthood.
Despite inconsistent recommendations regarding the routine assessment of cervical length during pregnancy (9, 10, 11), this study does recommend the targeted use of cervical length sonography. However, based on the findings of this study, there may not be a need for global cervical length evaluation but rather a regional and country-specific approach to allowing early interventions to reduce preterm birth rates.