Socio-demographic factors and cervical length in pregnancy

The cervical length is an important factor in the risk evaluation of preterm delivery. The aim of this work was to determine the correlation between the cervical length and the demographic characteristics. A transversal type prospective study was done on a sample of 579 pregnant women at various gestational age of low risk mono-fetal pregnancy. The cervical length was measured by trans-vaginal ultrasound procedure within the regular pregnancy monitoring process. The following data were taken into consideration: the woman's age, her body mass at the beginning of the pregnancy and her height in order to calculate the body mass index as well as her smoking habit at the moment of conception. The mean cervical length was 34.3 mm and 35 mm in the group of women aged 30 and less and 31 and over, respectively. The cervix was insignificantly shorter in younger women (being 34.9 mm/35.9 mm in the 1st trimester, 34.5 mm/35.1 mm in the 2nd one and 33.9 mm/34.7 mm in the 3rd trimester). The sample of 579 pregnant women consisted of 448 non-smokers and 131 smokers. The difference in the length of the cervix in smokers and nonsmokers was not significant (being 32.2 mm/35.9 mm; 35 mm/34 mm and 34.4 mm/33.5 mm in the 1st, 2nd and 3rd trimester, respectively). The correlation between the body mass index and the cervical length was analyzed by trimesters. In the first trimester the increase in the body mass index was followed by the shortening of the cervix; the cervical length was not affected by the BAI in the second trimester, whereas the higher the body mass index the longer the cervix in the third trimester. Our study has shown that the cervical length is affected neither by the age of the woman nor her smoking habit but it is affected by the body mass index at the moment of conception, that linear trend being negative in the 1st trimester but positive in the 3rd one. Since the cervical length may be affected not only by the socio-demographic characteristics but the gynecologic obstetric history of the woman as well, we strongly suggest further investigations in this field.