Analysis of the Impact of Cervical Excision Procedure on Delivery Mode

Background: Many young women with a history of prior cervical excision procedure have reproductive intention. However, the relationship between having a prior cervical excision procedure and delivery mode has not drawn enough attention from physicians. The aim of this study was to observe the delivery mode of women with a prior cervical excision procedure, and analyze the relationship between having a prior cervical excision procedure and delivery mode. Methods: In this retrospective cohort study of nulliparous women with a singleton pregnancy who have given birth at Beijing Obstetrics and Gynecology Hospital, Capital Medical University between May 2016 and April 2018, delivery mode of women with a history of prior cervical excision procedure were compared with those without such a history. Bivariable analysis were performed to identify whether there was a correlation between having a prior cervical excision procedure and delivery mode, and logistic regression were used modeling on cervical excision procedure for delivery mode outcome. Results: (1) The proportion of premature rupture of fetal membrane (38.3% vs 27.0%, p=0.034) , forceps delivery (12.2% vs 5.9%, p=0.043), and Caesarean sections delivery (33.9% vs. 30.2%,p=0.484 ) were higher among women with a prior cervical excision procedure. (2) The main indication for forceps delivery was to shorten the second stage of labor among women with a prior cervical excision procedure, signicantly higher (50% vs 7.7%, p=0.033) among women without such a history. There were no differences in indications for Caesarean sections delivery in two groups (p>0.05). (3) The time interval between cervical excision procedure and pregnancy was not associated with delivery mode (p=0.445). (4) By setting spontaneous labor as control, forceps delivery was associated with cervical excision procedure (OR=0.403, 95%CI=0.179-0.906, p=0.028). Conclusions: Our ndings revealed a relationship between having a prior cervical excision procedure and delivery mode. Women with a prior cervical excision procedure were at an increased risk of forceps delivery. The time interval between cervical excision procedure and pregnancy did

from cervical tissue [5,6]. This kind of surgery can not only make a damage to the cervical itself, but also affect the structure and function of uterus integrally.
An authoritative report showed that the incidence of cervical squamous intraepithelial lesion among all women in China was about 1.9% and the incidence of cervical excision procedure (LEEP or CKC) was about 1.3% [7]. The data of cervical squamous intraepithelial lesion was lower in Beijing, the capital of China, with an incidence of 0.6% [8]. Many young women with a history of prior cervical excision procedure have never given birth and have reproductive intention [9]. Between May 2016 and April 2018, 149 nulliparous women with a prior cervical excision procedure have given birth at Beijing Obstetrics and Gynecology Hospital, Capital Medical University. Thus, the impact of cervical excision procedure on delivery mode should be considered.
Controversy exists surrounding the impact of a prior cervical excision procedure on delivery mode. Prior studies showed that the incidence of Caesarean section rates among women with a prior cervical excision procedure varied widely, from 6.4-42.0% [6,[10][11][12][13][14]. Although, most studies demonstrated that a prior cervical excision procedure did not affect Caesarean section rates [10][11][12][13], some proved that Caesarean section rates were signi cant higher [14] or lower [6] among the women with a prior cervical excision procedure. In addition, the incidence of forceps rates among the women with a prior cervical excision procedure has not been calculated yet. Thus, the impact of cervical excision procedure on delivery mode still remains a controversial subject of debate.
The objective of this retrospective cohort study was to observe the delivery mode of women with a prior cervical excision procedure, and analyze the relationship between having a prior cervical excision procedure and delivery mode.

Study groups
This is a retrospective cohort study of women who have given birth at Beijing Obstetrics and Gynecology Hospital, Capital Medical University between May 2016 and April 2018. Among 149 nulliparous women with a history of prior cervical excision procedure, 115 women met the inclusion criteria and exclusion criteria, and were compared with 222 nulliparous women without such a history. The case and control subjects were matched by pre-pregnancy body mass index (BMI), weight gain during pregnancy, gestational age at delivery, tobacco use, alcohol use,pregnancy complications, fetal birth weight, nationality and area (1:2 matching), and only 222 women without a prior cervical excision procedure were conducted as control group. Study was approved by the Ethics Committee of the Beijing Obstetrics and Gynecology Hospital, Capital Medical University. (3) with invasive carcinoma of uterine cervix; (4) with a signi cant cerebrovascular, renal, hepatic, endocrine disease or any major disease.

DATA
Baseline clinical data, such as maternal age, pre-pregnancy body mass index (BMI), weight gain during pregnancy, gestational age at delivery, tobacco use, alcohol use, pregnancy complications (hypertensive disorders, gestational diabetes mellitus or diabetes mellitus), premature rupture of fetal membrane (PROM), delivery mode (spontaneous labor, forceps delivery or Caesarean sections delivery), fetal birth weight, time interval between cervical excision procedure and pregnancy, and indications for forceps or Caesarean sections were abstracted from the clinical records.
Time interval between cervical excision procedure and pregnancy was calculated from the day of cervical excision procedure to the rst day of last menstrual period among the women with a history of cervical excision procedure.

Statistical analysis
All statistical analysis were performed by using the SPSS 21.0 (SPSS Inc., Chicago, Illinois, USA). Quantitative variables were expressed as mean ± SD. Qualitative variables were expressed as "n (%)".

Non-normal distribution data were expressed by medians, quartiles and range. Student's t-test, χ 2 -test and
Fisher's exact test were used for comparisons, as appropriate. The Kruskal Wallis rank test was used to estimate different time intervals between cervical excision procedure and pregnancy in different delivery modes. Uni-variable multinomial logistic regression was used to determine whether having a prior cervical excision procedure was associated with delivery mode. All tests were 2-tailed and a P < 0.05 was considered signi cant.

Results
Main characteristics of patient strati ed by prior cervical excision procedure were shown in Table 1.
Women with a prior cervical excision procedure were older (32.8 ± 3.7 vs 30.9 ± 3.5, p < 0.001), and were more likely to have a PROM (38.3% vs 27.0%, p = 0.034). The proportion of forceps delivery (12.2% vs 5.9%, p = 0.043) or Caesarean sections delivery (33.9% vs. 30.2%, p = 0.484) were higher among women with a prior cervical excision procedure. The pre-pregnancy BMI, weight gain during pregnancy, gestational age at delivery, tobacco use, alcohol use, pregnancy complications (hypertensive disorders, gestational diabetes mellitus or diabetes mellitus), and fetal birth weight were comparable between the two groups (P > 0.05) ( Table 1).
The main indication for forceps delivery was to shorten the second stage of labor among women with a prior cervical excision procedure, signi cantly higher (50% vs 7.7%, p = 0.033) among women without such a history. Nevertheless, no differences were found in the indications for Caesarean sections delivery between the different groups ( Table 2).
The data suggested that time interval between cervical excision procedure and pregnancy was not signi cantly associated with delivery mode (p = 0.445) ( Table 3 Fig. 1). Table 4 showed uni-variable multinomial logistic regression analysis of cervical excision procedure for the outcome of delivery mode. By setting spontaneous labor as control, the result indicted that forceps delivery was associated with cervical excision procedure (OR = 0.403, 95%CI = 0.179-0.906, p = 0.028).

Discussion
The aim of our study was to observe the delivery mode of women with a prior cervical excision procedure, and analyze the relationship between having a prior cervical excision procedure and delivery mode.
Our study found that a prior cervical excision procedure was associated with an increased risk of forceps delivery(p = 0.034), and the main purpose of forceps delivery was to shorten the second stage of labor(p = 0.033). The cervix, which is consisted of smooth muscle, broblasts, epithelium, and blood vessels, is considered to play an important role in delivery [15,16]. Theoretically, cervical excision procedure has an impact on the structure and function of the uterus, which may affect the process of labor. Our study con rmed the theory which can be explained by three aspects below. First of all, excision leads an incomplete cervix, which can cause the dis-coordination of uterine contractions and low level of integral e ciency of uterine contractions, and uterus will exert less direct force on uterine contents. Secondly, cervix has the ability to adjust the position of fetal head, and an incomplete cervix can in uence position of fetal head which is more likely to lead a cephalic presentation dystocia. In addition, women with a prior cervical excision procedure were elder in our study, who might undergo a physiologic aging process of myometrial tissues and skeletal muscle [17]. Those three reasons may prolong the duration of the second stage of labor. Because a prolonged duration of the second stage of labor may increase potential risk for both mothers and infants, active treatments, such as forceps, to complete delivery are necessarily needed [18], which increases the risk of forceps delivery.
We did not nd an association between having a prior cervical excision procedure and Caesarean sections delivery(p = 0.484), similar with vast previous studies [10][11][12][13]. Theoretically, having a prior cervical excision procedure can affect the coordination of uterine contractions, which is more likely to result in dystocia and increases the risk of both forceps delivery and Caesarean sections delivery. However, our results did not con rm the inference.This was probably because the physicians didn't consider fully of the impact of a prior cervical excision procedure on the integral e ciency of uterine contractions, when they were selecting the proper delivery pattern. Those who should have a Caesarean section were suggested to go through a vaginal breech delivery. Because of the low level of integral e ciency of uterine contractions with an incomplete cervix, those women had to nish the delivery with the help of forceps, which increased the risk of forceps delivery and decreased the risk of Caesarean section delivery that was supposed to be.
Our study also indicated that the time interval between cervical excision procedure and pregnancy did not affect delivery mode (p = 0.445). It happens because cervix is a growing organ[19]; because uterus can repair itself in a short time with abundant vascularity; because during the long period of pregnancy, uterus grows slowly and has enough time to repair itself to suit pregnancy and delivery condition. However, Liverani et al [13] reported that women who became pregnant within 12 months since LEEP showed a signi cantly lower rate of cesarean sections (31.6% vs. 44.3%, P = 0.03) compared with women with a longer time interval from LEEP to pregnancy. Therefore, further study is still needed to increase the sample size, layer the time interval between cervical excision procedure and pregnancy, and observe the delivery mode between different layers of the time interval.
One of the strengths of this study is that few research have focused on forceps delivery after cervical excision procedure. The results can be used as references for delivery mode selection. Physicians should pay attention to the impact of a prior cervical excision procedure on delivery mode, select the delivery pattern properly, and keep both mothers and infants safe and healthy.

Conclusions
In conclusion, our data demonstrate that having a prior cervical excision procedure can signi cantly increase the risk of foreceps delivery compared with the general population. When physicians are selecting a proper delivery mode, having a prior cervical excision procedure should also be considered as an important indicator. 23. We focused on observing the delivery. mode of women with a prior cervical excision procedure, which was rarely mentioned in other articles.

Abbreviations
24. In our paper, we found that women with a prior cervical excision procedure were at an increased risk of forceps delivery compared with general population. And we presented the idea that the a prior excision procedure can cause low level of integral e ciency of uterine contractions, which may prolong the second stage of labor and increase the risk of forceps delivery.
25. The idea of. "integral e ciency of uterine contractions" is A WHOLE NEW THEORY which is inspired by Alexander Romanovich Luria, a soviet psychologist and neuropsychologist, who has presented the integrity of brain function theory. We believe that our theory-integral e ciency of uterine contractions, will arouse the awareness of physicians and should be considered as an important indicator for delivery mode selection among women with a prior cervical excision procedure.
26. The research should. appeal to a broad audience interested in delivery mode of women with a prior cervical excision procedure. We thus believe that the manuscript is appropriate for the readership of BMC Pregnancy and Childbirth.
27. We. remain at your disposal for any further questions.  Figure 1 Time interval between cervical excision procedure and pregnancy according to delivery mode

Supplementary Files
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