**3. Results**

In total, 166 women were examined sonographically and we found that 95 (57.2%) had cervical length less than 2.7 cm. Dilatation of the internal cervical os >10 mm was found in 138 (83.1%) women and funneling was found in 51 (30.7%). Thirty-nine women (23.5%) who had transvaginal sonographic assessment of the cervix had preterm labor under 33 weeks. Only 20 of 166 women of the study (12%) had a cervical cerclage procedure and 124 of them (74%) had a pessary placement. About the mode of delivery, 61 participants (36.7%) had normal vaginal delivery, 9 (5.4%) had vacuum extraction and 96 (57.8%) had a low segmen<sup>t</sup> cesarean section (Table 1).


**Table 1.** Cervical characteristics of participants and labor modus.

Table 2 describes the relationship between early labor under 33 weeks and the results of the transvaginal sonography. Logistic regression was used for the need of the specific study. As shown in Table 2, the prediction of labor under 33 weeks of gestation cannot be based on the results of transvaginal ultrasonography about cervical length and dilatation of the internal cervical os, since there is not enough statistical significance to support these specific cases. Of the 39 women who had an early preterm delivery, 25.6% had abnormal cervical length, whereas 21.12% had a normal one. However, this inference cannot be considered as a factor of early preterm delivery (*p* = 0.534 > 0.05). Women who had dilatation of cervical os >10 mm (25.3%) were more likely to have preterm delivery than those who did not (14.2%). However, for the same reason, a *p* value of 0.210 means that this factor cannot be considered. These results can also be perfectly explained in Figures 1 and 2. Concluding, if a woman has cervical diameter >10 mm or cervical length <2.7 cm or both, we cannot be definitely sure that she will have a delivery under 33 weeks. Funneling seems to be a predicting factor of grea<sup>t</sup> importance. It was found that there is a relationship between funneling and delivery under 33 weeks (YES = 39.2%, NO = 19.8%, *p* < 0.05). The treatment modus (cervical cerclage and pessary) were also checked in Table 3. Fifty percent of the ten women who had a placement of a cervical suture delivered under 33 weeks, whereas only 19.6% those who did not have a cerclage procedure had preterm labor under 33 weeks. The *p* value is <0.05 and this means that the result is statistically significant. In addition, it is concluded that the incidence of early preterm labor was significantly higher in women with cervical cerclage compared to women with no medical intervention. A group of women had a pessary placement. The outcome from the specific group was very encouraging. It was found that pessary does

not affect the week of delivery in an adverse way. According to our findings, statistical significance of age (*p* = 0.419), parity (*p* = 0.295) and labor modus was not confirmed.

**Figure 1.** The association of cervical length and pregnancy week (*p* = 0.534).

**Figure 2.** The association of cervical diameter and pregnancy week (*p* = 0.210).

**Table 2.** Cervical characteristics of the early preterm labor (<33 weeks) women. Bold type means statistical significance.



**Table 3.** Treatment of cervical insufficiency (cervical cerclage, pessary) of the early preterm labor (<33 weeks) women. Bold type means statistical significance.

As presented in Table 4, if a funneling exists in a woman, there is a three times higher risk of early preterm (Odds Ratio (OR) = 3.260, with Confidence Interval (CI): 1.544–6.881 and *p* < 0.05) and if she has a cervical cerclage placement, there is a four times higher risk of labor under 33 weeks. The placement of the pessary has a 1.7 higher risk of labor (OR = 1.750, CI: 0.503–2.721 and *p* > 0.05) under 33 weeks and it is not statistically significant, which means that it does not affect negatively as the cerclage procedure.

**Table 4.** Correlation between preterm labor and cervical characteristics expressed as odds ratio (OR) with 95% confidence intervals (CI).


Finally, in Table 5, the groups of women with one, two or no invasive characteristics are examined. Forty women with both cerclage and pessary had a grea<sup>t</sup> possibility of early preterm delivery (*p* < 0.05). For women who had no surgical intervention and had only pessary, there was less possibility (*p* = 0.139) for preterm delivery, which means that pessary is a procedure that does not affect negatively the week of labor. As far as the group of women who underwent a cerclage is concerned, there is no statistical significance (*p* = 0.401), which means that it cannot cause early preterm labor. Unfortunately, there is not enough evidence to rule it out (because there were only two cases).

**Table 5.** Labor outcome after treatment of cervical insufficiency (cervical cerclage, pessary). Bold type means statistical significance.


On the other hand, judging from the second and the last line of Table 4, we can see that pessary placement (second line) does not cause preterm labor under 33 weeks, but what make women of the last group have a delivery under 33 weeks is that they have also a placement of a cervical suture during the second trimester and it is presumed harmful for these women concerning their preterm labor.

By using logistic regression, we also managed to create three equations, in which we can predict if the week of labor is under 33, taking into account only the physical features (Equation (1)), only the invasive characteristics (Equation (2)), or both physical and invasive characteristics. If every feature is substituted by 0 or 1 according to the sample, then multiplied with the specific coefficient and added to the constant number of the first column, we find a number which will be very close to 0 or 1, representing the week of labor (early preterm labor <33 is 0, preterm labor is 1). The formulas are the following:

Week = cervical length × (0.136) + cervical diameter × (−0.242) + funneling × (−1.112) + 1.745 (1)

$$\text{Week} = \text{pessary} \times (0.011) + \text{cercage} \times (-1.397) + 1.387 \tag{2}$$

Week = cervical length × (0.123) + cervical diameter × (−0.398) + funneling × (−0.983)+ pessary × (0.503) + cerclage × (−0.740) + 1.568 (3)

with cervical length (<2.7 = 0, >2.7 = 1), cervical diameter (>10 = 0, <10 = 1), funneling (yes = 1, no = 0), cerclage (yes = 1, no = 0), and pessary (yes = 1, no = 0).
