Maternal Outcome in Pregnant Women Undergoing Third Caesarean Section After Onset of Labor

Abstract

Background/Aim

Our study compares repeat cesarian section with and without labor in progress and evaluates adverse maternal outcomes that could discourage pregnant women in planning labor at term or at least after 39 weeks of gestation as recommended due to benefits in neonatal outcome.

Patients and Methods

In this retrospective study, we analyzed 191 patients undergoing third C-section and compared two groups of women of undergoing C-section either before or after the onset of labor. The primary outcome measure was the incidence of maternal morbidity. Values of p≤0.05 were regarded as significant.

Results

Comparing the two subgroups, we did not find any significant differences in the occurrence of maternal complications or severe acute morbidity except for incomplete uterine rupture (p=0.04).

Conclusion

Undergoing a third C-section after the start of labor has no relevant or adverse impact on maternal outcome. Therefore, elective repeat C-section can be planned in late weeks of gestation aiming at reducing neonatal morbidity. The higher rate of uterine dehiscence was not associated with other issues of severe acute maternal morbidity.

The cesarean section (C-section) is one of the most common operations globally and the most frequent in women (1). The global incidence of C-sections lies at 21.1%, with variations between regions: in most industrialized countries, it ranges between 15% and 30%. The global incidence has increased by 5% in the past 30 years (2). With the increase in incidence of the overall C-section rate, the number of women giving birth again following one or several cesarean sections has also consistently increased: in the USA, the rate of repeat C-sections in the year 2022 was at 85.4% (3). In Germany, the rate in 1979 was already 23.6% of all C-sections, and by 2020, it had risen to 33.2% (4).

There are still open questions regarding the best care for pregnant women with a previous C-section in their medical history, both regarding the mode of birth and the optimal time of delivery. Neither the German nor the international guidelines provide specific recommendations in such cases. The desire to benefit the fetus by inducing birth late in the pregnancy has to be weighed against the fear of increased maternal morbidity and mortality in the event of a C-section carried out after the start of labor.

The C-section is considered a relatively safe procedure, with an operation-related mortality rate of just 0.02-0.1% today (5); nonetheless, this intervention is associated with some potentially serious risks (6,7). In particular, women with repeat births by C-section have an increased risk of maternal complications and severe acute maternal morbidity (SAMM): adhesions and injury to adjacent organs, peripartum hemorrhage, blood transfusion, rupture or dehiscence of the uterus, hysterectomy, and stays in the intensive care ward were significantly higher in women who had undergone a higher number of C-sections (8-14). Consequently, operative times and in-patient stays were extended. Subsequent pregnancies have also been found to be associated with significantly higher incidences of placenta praevia, uterine dehiscence and rupture, and placenta accreta (8). Such risks and complications need to be considered when advising pregnant women regarding preparing for delivery, and planning for another child (14).

In addition to the decision on the desired mode of birth and the associated risks, another important aspect is the optimal time of delivery. To lower the risk of neonatal morbidity, it is generally recommended that the delivery be close to term and not before week 39+0 of the pregnancy (15-18). The onset of labor contractions has a positive influence on reducing the occurrence of neonatal respiratory adaptation disorders (19). As shown by Morrison et al., neonatal morbidity was significantly increased when C-sections were carried out before the start of labor (planned C-sections) compared to vaginal births and C-sections after the start of contractions and/or the rupture of the membranes (emergency C-sections) (20). As a result, aiming for and experiencing contractions and the rupture of the membranes is the focus of modern obstetrics, regardless of the success of an attempted vaginal birth.

This analysis will attempt to discover whether these recommendations for a late time of delivery should also be given to women who have already undergone several C-sections or whether increased maternal morbidity should be expected in such cases, which should be balanced against neonatal benefits, and should result in a recommendation against a late time of delivery.

To identify the difference in maternal outcomes and severe acute maternal morbidity between planned and emergency repeat C-sections, we analyzed the data of the women who underwent a third C-section at our clinic, a Level I perinatal center with one of the highest numbers of births in Germany.

Patients and Methods

This retrospective cross-sectional study evaluated the delivery data between January 2015 and December 2020 of the Obstetrics Clinic of the Florence Nightingale Hospital in Düsseldorf, Germany. It was approved by the Medical Department of the University of Cologne, following their Guidelines for Safeguarding Good Academic Practice. The study included women who underwent a C-section in the defined period and who had had at least two previous C-sections. For a better understanding, Figure 1 shows a flowchart of the inclusion of examined women.

Figure 1.

Flowchart of the study inclusion.

For better comparability, multiple births were excluded from the study, and the analysis was restricted to the investigation of those undergoing a third C-section.

The cohort of 191 patients was divided into two sub-populations: planned C-section and emergency C-section, based on the absence or presence of cervical contractions and/or an early rupture of membranes at the time of surgery.

The comparison focused primarily on the maternal outcome in the two groups, defined by the appearance of SAMM: injury to adjacent organs, deep vein thrombosis, postoperative infection, sepsis, shock, hysterectomy, acute kidney failure, pulmonary embolism, cardiac arrest, and maternal mortality.

Operative and basic clinical data, such as the duration of the operation, time to delivery, blood loss, duration of in-patient stay and incidence of mild or severe anemia at discharge, were also analyzed.

The basic data were collected using our hospital’s database software (ViewPoint™; GE HealthCare Deutschland, Munich, Germany) and digitally archived patient files with operation reports, discharge and transfer reports, as well as documentation on clinical progression. The investigated parameters are shown in Table I; data were anonymized prior to analysis.

Table I. Investigated parameters.

BMI: Body mass index. ¹Except C-section(s) in medical history. ²Separately collected for every delivery. ³Definition by Allgöwer and Burri (23). ⁴No anemia: Hb ≥9.0 g/dl; mild anemia: Hb 7.0-8.9 g/dl and no blood units; severe anemia: Hb <7 g/dl or ≥1 transfused blood units.

The statistical evaluation of the data was carried out using the Statistical Package for the Social Sciences Version 15.0.1 (SPSS Inc., Chicago, IL, USA).

For the descriptive statistics, the quantitative parameters are presented as the mean and the standard deviation as well as the minimum and maximum values (range) and the most important percentile. Qualitative data are described based on their absolute and percentage frequency. The chi-squared test was used to compare the groups’ qualitative parameters.

To draw conclusions based on our statistical analysis, nominally scaled variables were assessed using Pearson’s chi-squared test. For individual questions regarding ratio-scaled variables, the Mann-Whitney U-test was used. Values of p≤0.05 were considered to be statistically significant.

Firstly, a systematic literature review was carried out using medical databases, such as Pubmed, Elsevier, and Cochrane Library. Combinations of various medical-subject heading terms were used, taking into consideration the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) (21). Articles not published in German or English were not considered. The literature search ended in April 2024.

Mendeley Reference Manager was used as the literature management program.

Results

Evaluation of the population. Overall, 191 women from the database who had undergone a third C-section at our clinic were included, 12 of whom gave birth to more than one child. The mean age was 34 years (Figure 2).

Figure 2.

Maternal age at third C-section.

Of the 191 women included in the study, 57.1% underwent the third C-section for their third pregnancy, another 25.7% for their fourth pregnancy. The remaining 17.3% had had several pregnancies, the highest number being seven. In 94.8% of cases, the third C-section was also the third birth. The remaining cases were fourth births (4.2%) and fifth births (1%).

Table II shows an overview of the clinical comparative parameters: The median duration of pregnancy was 267 days, corresponding to 38+1 weeks of pregnancy (see Figure 3).

Table II. Overview of various medical history and intra-operational comparative parameters in the population of women who delivered via a third C-section.

BMI: Body mass index; Hb: hemoglobin.

Figure 3.

Gestational age at delivery.

The median body mass index of the pregnant women at the time of delivery was 25.6 kg/m² and ranged from 17.3 to 42.1 kg/m² across the 191 cases as shown in Figure 4.

Figure 4.

Body mass index (BMI) of mother at delivery.

Of the 191 participants, 165 (86.4%) had had no prior abdominal operations except for the C-sections. Twenty-six women (13.6%) had had one (12%) or two (1.6%) abdominal operations in addition to previous C-section.

On average, there were 8.8 years between the first C-section and the last (third). The shortest period was four years, the longest was 21 years (cf. Figure 5).

Figure 5.

Distribution of the time between the first and last C-section in the population.

The average time between incision and stitching was 52 minutes and ranged from 20 to 105 minutes (Figure 6). A total of 43 women were excluded because they additionally underwent sterilization by salpingectomy during the operation (148 cases remaining).

Figure 6.

Distribution of the time from incision to stitching for third C-sections.

For the overall population of 191 women, an average of 8.7 minutes passed between incision and delivery. The duration ranged from 1 minute for the fastest to 50 minutes for the longest, as illustrated in Figure 7. Average blood loss was 561 ml (Figure 8).

Figure 7.

Distribution of the time from incision to delivery in the whole cohort.

Figure 8.

Intra-operative blood loss in all third C-sections.

Twelve out of 191 cases (6.8%) suffered iatrogenic injuries to adjacent organs, mainly to the parametrium (4.7% of all C-sections). A uterine rupture was described in 23 cases (12%), all of which were partial ruptures or dehiscence.

In 13 out of 191 cases (6.8%), there were further cases of SAMM during or following the operation. Table III shows the incidence of one or more parameters. Table IV lists the individual SAMM complications in absolute and relative terms.

Table III. Number of severe acute maternal morbidity (SAMM) complications during planned and emergency C-sections.

Table IV. Comparison of the incidence of SAMM and other maternal complications during third C-section for planned and emergency C-sections.

Statistically significant p-values are shown in bold.

Comparison of complications between planned and emergency third C-section. Table II includes the parameters intra-operative blood loss and hemoglobin value at discharge, comparing planned and emergency third C-sections. There was no significant difference for any of the parameters.

The average blood loss considering all 191 deliveries was 561 ml. When divided into planned and emergency C-sections, the analysis found an average blood loss of 541 ml for planned C-sections and 538 ml for emergency C-sections (p=0.46). At 1,300 ml, the maximum documented blood loss was lower for emergency third C-sections than for planned C-sections (2,000 ml).

Blood loss resulted in anemia in 33 out of the 191 cases (17.3%). No significant difference was identified between planned (19.4%) and emergency (8.3%) C-sections (p=0.12) in regard to blood loss. The anemia cases were then further divided into mild anemia (Hb value between 7.0 and 8.9 g/dl) and severe anemia (Hb value under 7 g/dl or administration of ≥1 blood unit). Blood transfusions were included to consider cases of high blood loss in patients who had a comparatively high Hb value because of a red blood cell transfusion when investigating anemia requiring treatment. Based on this definition, severe anemia occurred in only two cases, both in the planned C-section sub-group. This corresponds to 1% of all C-sections, 1.3% in the respective sub-group (p=0.27). The mean Hb value at discharge was approximately 10 g/dl in both sub-groups, with a difference of just 0.3 g/dl.

The comparison of the Hb value revealed not just a similar nominal mean value, but also a narrower distribution for the emergency C-section group: the standard deviation was 1.10 g/dl for the emergency group, compared to 1.35 g/dl in the planned group (p=0.20); this is shown in Figure 9.

Figure 9.

Distribution of the hemoglobin value at discharge, according to planned and emergency third C-section.

The only transfusion (two units of blood) in the entire population was necessary for one of the planned C-sections (0.6% of planned and 0.5% of all C-sections, p=0.63).

Table IV lists the individual complications and SAMM with their absolute and relative frequencies and compares the two parameters for the planned and emergency C-sections.

Overall, there were injuries in nine out of 146 planned C-sections. This represents 5.8% of all cases, with two cases (1.3%) suffering several simultaneous injuries. There were four cases of injury in 32 planned deliveries, almost double the rate at 11.1%; with a p-value of 0.25, this difference was not significant.

One or more SAMM complications occurred in a total of nine planned C-sections, corresponding to 5.8% of this sub-group. In comparison, four out of 32 patients (11.1%) suffered a SAMM when their third C-section was carried out as an emergency (p=0.25). Table III additionally lists the incidence of one or more SAMM complications.

The risk of uterine rupture was significantly higher in the population of patients undergoing their third C-section as an emergency than in those undergoing it as planned (p=0.04).

Eight out of 36 cases suffered a rupture (22.2%) in emergency operations. In contrast, the rate for planned C-sections was only 9.7% (15 of 155). All cases of rupture in the population were partial ruptures.

Discussion

There is little evidence and no precise treatment algorithms to provide obstetric advice and planning for women with several prior C-sections. Maternal morbidity increases with the number of C-sections. A vaginal birth after previous cesarean delivery can be considered; the risk for the mother is higher in relative terms but low in absolute numbers (8-14).

For the sake of the fetus, pregnant women are usually advised to plan for delivery as close to term as possible unless there are medical grounds not to do so. Planned C-sections should thus not be planned before the 40th week of pregnancy (15-19,22).

The data from our analysis can improve advice for women who have already undergone two C-sections and who, for their next pregnancy and after considering the type of delivery, opt for a third C-section. According to our findings, the recommendation to carry out the operation close to term can also apply to this form of repeat C-section.

The analysis of the patients who delivered via a third C-section showed only a significantly higher incidence of uterine dehiscence in the emergency subgroup. The other investigated SAMM variables, as well as other parameters of the procedure and the postoperative treatment, revealed no statistically significant disadvantage for women undergoing an emergency third C-section (cf. Table IV).

As seen in Table II, we recorded a mean delivery date of 267 days in the total population, corresponding to 38+1 weeks of pregnancy, which contradicts the recommendations above for the optimal delivery time for the fetus. One reason for this may be the subjective assessment of both the patients and their treating medical staff that choosing an earlier delivery time results in fewer complications during third C-sections. Our investigation disproved this assessment and thus has delivered important insights for everyday obstetric consultations with pregnant women.

Finally, it should be stated that our data yielded almost no statistically significant findings (cf. Table IV) and that, therefore, further analyses with larger populations are required. However, gathering additional data from a larger population is difficult because third C-sections are much less frequent than first and second ones. The flow diagram of our study in Figure 1 shows the low proportion of third C-sections, representing just 1.28% of all deliveries. Because we did not find any similar studies, a meta-analysis also cannot be conducted. Alternatively, one could extend the investigation to the data held by other obstetric clinics in the form of a multi-center study.

Conclusion

To preserve the benefits for the child of a delivery as close to term as possible, when planning a third C-section, it can be scheduled late in the pregnancy and even after the start of contractions, as there should be no increased maternal morbidity compared to a first C-section.

Pregnant women envisioning a vaginal delivery after two previous C-sections can be reassured by the fact that even an interrupted vaginal birth and subsequent emergency (third) C-section should not come with any greater risks than a planned C-section.

Conflicts of Interest

The Authors declared no potential conflicts of interest concerning the research, authorship, and/or publication of this article.

Authors’ Contributions

B.L and M.M. conceived the study, curated and interpreted data. M.M. and A.I. collected clinical data. M.M. evaluated the data, performed the statistical analysis and wrote the article. P.M. and B.L. supervised the project and critically revised the article. All Authors read and approved the final version of the article.

The data that support the findings of this study are available from the corresponding author, MM, upon reasonable request.