(447) Cervical length nomograms for singleton pregnancies

The study took place within a health maintenance organization (HMO) with more than 2.5 million insured population. HMO databases were retrospectively searched between the years 2012-2020. Data was extracted for all women with singleton pregnancies from week 16 to week 36 .A statistical modal was constructed in order to calculate the 5^th, 10^th, 25^th, 50^th, 75^th, 90^th, and 95^th percentiles for each pregnancy week.

Results:

144,961 women and 249,404 cervical length measurements were included in our analysis. The median number of one cervical measurement per woman was 1 (1.72-/+1.45). The study population included women between the ages of 16-52 years with a median age of 30 years. The maximal number of cervical length measurements was noted at 22 week of pregnancy (30,518 measurements) and the minimal number of cervical length measurements was included for 34 weeks of pregnancy (393 measurements).

When reviewing the 5^th and 50^th percentiles through the different pregnancy weeks, consistent progressing cervical shortening is observed. At 18 and 24 weeks of pregnancy, the 5^th percentiles are 31 mm and 30 mm, respectively, and at 30 and 34 weeks of pregnancy, the 5^th percentiles are 22 mm and 16 mm, respectively. Similarly, change is observed in the 50^th percentiles – cervical length of 40 mm at 18 and 24 weeks of pregnancy and 38 mm and 34 mm at 30 and 34 weeks of pregnancy respectively. Nomograms are displayed in Table 1.

Conclusion:

Cervical length nomogram based on 249,404 measurements of singleton gestation demonstrates that the cervical length tends to shorten as pregnancy progresses.  Those observations can assist in the management and treatment of women by providing tailored medical care throughout pregnancy.