Maternal and obstetrical factors associated with short cervical length at midtrimester in women with no history of preterm delivery

Abstract

Aim

To evaluate associations between maternal characteristics and a short cervix in patients without history of preterm delivery, and to determine if these characteristics can predict the presence of a short cervix.

Materials and methods

This is a retrospective cohort study that included 18,592 women with singleton pregnancies without history of previous preterm deliveries who underwent universal transvaginal cervical length (TVCL) screening between 18 + 0 and 23 + 6 weeks/days of gestation. A short cervix was defined as a cervical length (CL) ≤25 mm, ≤20 mm, and ≤15 mm. Associations between maternal age, weight, height, body mass index (BMI), previous term deliveries, and history of previous miscarriages, with a short cervix were evaluated using logistic regression models.

Results

The prevalence of a short cervix in our population was: CL ≤25 mm, 2.2% (n = 403); CL ≤20 mm, 1.2% (n = 224); and CL ≤15 mm, 0.9% (n = 161). Women with BMI >30 and/or previous abortions constituted 45.5% of the total population (8463/18,582). Significant associations with short cervix were observed for women with BMI ≥30, and for women with at least one previous abortion (p < .001). Parous women had a significantly lower association with a short cervix than nulliparous women (p < .001). Maternal age or height were not associated with a short cervix. Prediction of short cervix based on presence of any of the following: BMI ≥ 30 or previous abortions showed sensitivities of 55.8% (≤25 mm), 61.6% (≤20 mm), and 63.4% (≤15 mm) with similar specificity (50.1–54.6%) and likelihood ratio positive (1.2–1.5); and prediction based on BMI ≥ 30 and previous abortions showed sensitivities of 11.1% (≤25 mm), 14.7% (≤20 mm), and 16.7% (≤15 mm) with specificity 93%.

Conclusions

Among low risk women for spontaneous preterm delivery, those with a BMI ≥30 and/or previous miscarriages had a significantly increased risk for a short cervix at 18 + 0 and 23 + 6 weeks/days of gestation. Despite these significant associations, screening by maternal risk factors in a low risk population of pregnant women should not be an alternative to mid-trimester universal CL measurement.

Key message

In pregnant women evaluated at 18/0 and 23/6 weeks + days of gestation without history of preterm delivery, a 16.7% detection rate for short cervix ≤15 mm can be achieved by risk factors BMI ≥30, and at least one previous miscarriage. Nevertheless, screening for short cervix by risk factors among low risk women might not be an effective alternative to universal cervical length screening.

Keywords:

• Obesity
• obstetric history
• preterm delivery
• prevention
• risk factors
• screening

Acknowledgements

The authors thank all RDMS sonographers who contributed in the implementation and establishment of the universal transvaginal cervical length-screening program in the University of Texas McGovern Medical School Department of Obstetrics and Gynecology.

Author contributions

All authors contributed to the conception or design of the work and participated in the review, drafting, and final approval of the manuscript.

Ethical approval

Data evaluation complies with the guidelines for human studies, and data collection was conducted ethically in accordance with the World Medical Association and the Declaration of Helsinki, under Institutional Review Board approval (HSC-MS-14-0632).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

No funding sources were required for the preparation of this manuscript.