Cervical consistency index is a valid predictor of preterm birth in low-risk pregnant women

Main Article Content

Parichehr Pooransari
Fatemeh Salehi
Maryam Afrakhteh
Masoumeh Mirzamoradi
Soraya Saleh Gargari
Omid Ghatreh Samani


Preterm birth (PTB) remains a global problem associated with perinatal morbidity, including low birth weight, growth retardation and irreversible damage to the nervous system. The objective of this study was to determine the predictive value of cervical consistency index (CCI) to indicate the occurrence of PTB in mid trimester screening of low risk pregnant women.

This was a prospective study conducted on low-risk pregnant women at 14-28 weeks of pregnancy. The cervical length (CL) and AP cervical diameter were measured and the CCI determined according to the formula AP2/AP1*100. The ROC curves were drawn according to gestational age and the sensitivity and the specificity were calculated for optimal cut-off for 1st, 5th, 10th, 21th, and 24th centiles of CCI. The inter-observer agreement was validated by interclass correlation coefficients (ICC).

A total of 149 participants were enrolled in this study. Among them, 12.08% had PTB (<37weeks) and 87.92% had normal birth. Mean CCI for all subjects was 68.60%, but was lower in PTB (48.9%). The best cutoff for predicting PTB based on CCI was 59.46% with 99.18% sensitivity and 85% specificity. The AUC for CCI for prediction of PTB <37weeks was 0.936. There was no inter-observer difference in measurement of CCI and CL (ICC values for CCI and CL were 0.997 and 0.990 respectively).

In women with normal CL the CCI could predict PTB in the second trimester in low risk women. So, CCI is a valid predictor of PTB in low risk women.

Article Details

How to Cite
Pooransari, P., Salehi, F., Afrakhteh, M., Mirzamoradi, M., Saleh Gargari, S., & Ghatreh Samani, O. (2018). Cervical consistency index is a valid predictor of preterm birth in low-risk pregnant women. Universa Medicina, 37(2), 150–158. https://doi.org/10.18051/UnivMed.2018.v37.150-158
Original Articles


Kemp MW. Preterm birth, intrauterine infection, and fetal inflammation. Front Immunol 2014;5:574. doi: 10.3389/fimmu.2014.00574.

World Health Organization. Preterm birth. Geneva: World Health Organization;2017.

Blencowe H, Cousens S, Oestergaard MZ, et al. National, regional, and worldwide estimates of preterm birth rates in the year 2010 with time trends since 1990 for selected countries: a systematic analysis and implications. Lancet 2012;379:2162-72. doi: 10.1016/S0140-6736(12)60820-4.

Saigal S, Doyle LW. An overview of mortality and sequelae of preterm birth from infancy to adulthood. Lancet 2008;371:261-9. doi: 10.1016/S0140-6736(08)60136-1.

Hafstrom M, Kallen K, Serenius F, et al. Cerebral Palsy in Extremely Preterm Infants. Pediatrics. 2018;141:e20171433. doi: 10.1542/peds.2017-1433.

Lawson MJ. The role of inflammation in the pathogenesis of preterm birth [thesis].Cincinnati, Ohio: University of Cincinnati; 2017.

Gargari SS, Kashanian M, Zendedel H, et al. Survival and risk factors of extremely preterm infants (<28 weeks) in the three Iranian Hospitals. Acta Medica Iranica 2018;56:181-8.

Simmons LE, Rubens CE, Darmstadt GL, et al. Preventing preterm birth and neonatal mortality: exploring the epidemiology, causes, and interventions. Semin Perinatol 2010;34:408-15.

Tamura N, Hanaoka T, Ito K, et al. Different risk factors for very low birth weight, term-small-for-gestational-age, or preterm birth in Japan. Int J Environ Res Public Health 2018;15:369. doi: 10.3390/ijerph15020369.

Koullali B, Oudijk MA, Nijman TA, et al. Risk assessment and management to prevent preterm birth. Semin Fetal Neonatal Med 2016;21:80-8. doi: 10.1016/j.siny.2016.01.005.

Myers KM, Feltovich H, Mazza E, et al. The mechanical role of the cervix in pregnancy. J Biomech 2015;48:1511-23. doi: 10.1016/j.jbiomech.2015.02.065.

Romero R, Nicolaides K, Conde‐Agudelo A, et al. Vaginal progesterone decreases preterm birth 34 weeks of gestation in women with a singleton pregnancy and a short cervix: an updated meta‐analysis including data from the OPPTIMUM study. Ultrasound Obstet Gynecol 2016;48:308-17. doi: 10.1002/uog.15953.

Facco FL, Simhan HN. Short ultrasonographic cervical length in women with low-risk obstetric history. Obstet Gynecol 2013;122:858-62. doi: 10.1097/AOG.0b013e3182a2dccd.

Dekker GA, Lee S Y, North RA, et al. Risk factors for preterm birth in an international prospective cohort of nulliparous women. PLoS ONE 2012;7:e39154. doi: 10.1371/journal.pone.0039154.e39154.

Iams JD, Romero R, Culhane JF, et al. Primary, secondary, and tertiary interventions to reduce the morbidity and mortality of preterm birth. Lancet 2008;371:164-75. doi: 10.1016/S0140-6736(08)60108-7.

Parra-Saavedra M, Gomez L, Barrero A, et al. Cervical consistency index: a new concept in uterine cervix evaluation. Ultrasound Obstet Gynecol 2011 ;38:44-51. doi: 10.1002/uog.9010.

Banos N, Julia C, Lorente N, et al. Mid-trimester cervical consistency index and cervical length to predict spontaneous preterm birth in a high-risk population. Am J Perinatol Rep 2018;8:e43–50. https://doi.org/10.1055/s-0038-1636993.

Banos N, Murillo-Bravo C, Julia C, et al. Mid-trimester sonographic cervical consistency index to predict spontaneous preterm birth in a low-risk population. Ultrasound Obstet Gynecol 2017;51:629-36. doi: 10.1002/uog.17482.

Cazanas A, de San Miguel A, Parra E. Estimating sample size for usability testing. Enfoque UTE 2017;7:172-85.

Stolarova M, Wolf C, Rinker T, et al. How to assess and compare inter-rater reliability,agreement and correlation of ratings: an exemplary analysis of mother-father and parent-teacher expressive vocabulary rating pairs. Front Physiolog 2014;5:1-13. doi: 10.3389/fpsyg.2014.00509.

Amini P, Maroufizadeh S, Samani RO, et al. Prevalence and determinants of preterm birth in Tehran, Iran: a comparison between logistic regression and decision tree methods. Osong Public Health Res Perspect 2017;8:195-200. doi: 10.24171/j.phrp.2017.8.3.06.

Martin J, Hamilton B, Ventura S, et al. Births: final data for 2010. Natl Vital Stat Rep 2012;61:1–72.

Liu L, Oza S, Hogan D, et al. Global, regional, and national causes of child mortality in 2000–13, with projections to inform post-2015 priorities: an updated systematic analysis. Lancet 2015;385:430-40. doi: 10.1016/S0140-6736(14)61698-6.

Goldenberg RL, Culhane JF, Iams JD, et al. Epidemiology and causes of preterm birth. Lancet 2008;371:75-84. doi: 10.1016/S0140-6736(08)60074-4.

Donoghue D, Lincoln D, Morgan G, et al. Influences on the degree of preterm birth in New South Wales. Aust N Z J Public Health 2013;37:562–7.

Myers KM, Feltovich H, Mazzad E, et al. The mechanical role of the cervix in pregnancy. J Biomech 2015;48:1511–23. doi:10.1016/j.jbiomech.2015.02.065.