Background

Cesarean section (CS) is the worldwide process of pregnancy termination that delivers live or dead fetuses with an incision on the abdominal wall and uterine wall [1]. In the last decades, cesarean section has been performed to be a safe operation and improved the parturition outcome [2]. In America, the overall maternal mortality rate varies from 6 to 22 per 100,000 live births, and one-third or one half of the deaths attributed to the cesarean delivery that should be done [3]. CS has been rose in its frequency in many countries around the world [4, 5]. The previous studies have reported that the incidence of CS in the developed countries varies from 10 to 25%, while studies in India showed the cesarean rates varied between 8 and 36% [6, 7].

Though the rate of cesarean section has steadily increased and usually it is lifesaving, the procedure by itself carries risks and may increase the mortality and morbidity of mother and new born when compared to vaginal delivery [8,9,10]. Some studies have reported that the recovery time and intra- and post-operative complications of cesarean section, especially the emergency cesarean section (EmCS) [11, 12]. Postpartum maternal complications of cesarean sections include infection of wound and chest, blood transfusion complications, postpartum hemorrhage, burst abdomen, urinary tract infections (UTI), disseminated intravascular coagulation (DIC), fever caused by infection, and other inflammation like endometritis, and mainly postpartum fetal complications consist of birth asphyxia, transient tachypnea of newborn (TTN), respiratory distress syndrome (RDS), sepsis, and soft tissue injury. Because of the inherent risks, World Health Organization stated that there is no justification for any region to have cesarean section rates higher than 10–15% [13]. Concerning these various and severe complications of pregnant women and fetuses, guidelines were established and implemented and cesarean section should be performed when some specific defined indications presented [14].

EmCS is a cesarean section that conducted in an emergence, and the indications consist of fetal distress, cephalopelvic disproportion, failure to induce labor, none progress of labor, and previous cesarean delivery [15, 16]. Another important reason of choosing cesarean section in present is the increase in maternal age [4]. Elective cesarean section (ElCS) is a procedure that is generally done around 39 weeks when the incidence of newborn with tachypnoea is much less. Several indications mentioned above are also observed in the indication of ElCS, and another main indication is the previous surgery of cesarean section. The relative risk for emergency CS was 1.7 times more than that of elective CS apart from antenatal complications and medical disorder [17]. ElCS may reduce the incidence of maternal morbidity and mortality, and it is not surprising that older mothers tend to automatically require elective cesarean section.

Although the types of complication in ElCS and EmCS were similar, several studies have reported that the rates of post-operative complications after ElCS and EmCS were different [18, 19], and the current study aims to synthetically establish comparisons of the main maternal and fetal complications and outcomes in two groups of pregnancy between ElCS and EmCS.

Materials and methods

Search strategy

Related studies about the maternal and fetal complications and outcomes of ElCS and EmCS were comprehensive searched in multiple databases, including PubMed, Springer, EMBASE, Wiley-Blackwell, and China Journal Full-text Database. The systematic review and meta-analysis was undertaken with articles published from inception to October 2016 with all publication statuses (published, unpublished, in press, and in progress). The articles were searched independently and efficiently with the following keywords: (1) maternal OR fetal; (2) complication OR outcome; (3) elective cesarean section OR emergency cesarean section OR ElCS OR EmCS. All these terms were assembled with the connection symbol “AND” to search the articles related in the databases. To obtain more relevant studies and higher accuracy, the reference lists of each article we searched out should also be reviewed.

Citation selection

All the articles after the first screening were reviewed for the further selection. The titles and abstracts of these articles were screened independently and attentively. Then, the full text of the studies was obtained if the study was likely to be relevant.

The following inclusion criteria must be met in the citations included in this study:

  1. 1.

    a randomized control trial study or a controlled clinical trial study;

  2. 2.

    comparison of the morbidity and mortality between ElCS and EmCS;

  3. 3.

    availability of full text.

Exclusion criteria:

  1. 1.

    not a randomized study;

  2. 2.

    studies on other means of pregnancy other than cesarean section;

  3. 3.

    studies lacking outcome measures or comparable results.

The articles finally included were determined by these two investigators together. They checked whether the study was met the conditions presented above.

Data extraction

Two reviewers read the full text of the articles independently and extracted the relevant data of each study into coding sheets in Microsoft Excel software. In this study, the characteristics extracted consisted of the first author’s name, year of publication, year of onset, sample size (ElCS/EmCS), age range of pregnant woman, and outcome parameters. The extracted parameters included the maternal and fetal complications of ElCS and EmCS and infant mortality rate.

Statistical analysis

The meta-analyses were performed with the Review Manager 5.0 (The Cochrane Collaboration, 2011) to estimate the difference of complication rates and infant mortality rates between ElCS and EmCS, and STATA 10.0 software was used to estimate the publication bias. Q statistics was used to reflect the levels of heterogeneity. A random-effect model was adopted when heterogeneity I 2 statistic >50%, which means that the moderate or high heterogeneity was obtained; otherwise, a fixed-effect model was chosen. We performed the sensitivity analysis and bias analysis to the quality of included articles, and risk of bias of the included studies was assessed with the following criterions: (1) random sequence generation, (2) allocation concealment, (3) blinding of participants and personnel, (4) blinding of outcome assessment, (5) incomplete outcome data, (6) selective reporting, and (7) other bias. In our studies, all parameters were binary variables and related risk (RR) with 95% confidence intervals (CIs) was calculated. Funnel plots together with Egger’s tests were also applied to assess possible publication bias. P value <0.05 was considered that statistically significant was observed.

Results

Search results

A total of 1137 related titles and abstracts were initially searched out in electronic databases, and after an in-depth review, nine articles [18,19,20,21,22,23,24,25,26] eventually met all the inclusion criteria. The other 1128 articles were excluded for duplication, irrelevant studies, without a control group, incomplete data or comparison, other operations, reviews, or not a full text. Figure 1 shows the flow diagram of the study identification, inclusion, and exclusion that reflects the search process and the reasons of exclusion. Among these nine articles, seven were involved in the maternal complication of post-operation, three were involved in the fetal complication of post-operation, and four were involved in the fetal outcomes.

Fig. 1
figure 1

Flow diagram of the study identification, inclusion, and exclusion

Full size image

Characteristics of included studies

Details of the included articles are presented in Table 1. The first author’s name, year of publication, year of onset, sample size (ElCS/EmCS), age range of parturient woman, and sand outcome parameters of each study are shown in Table 1. All these articles were published from 2012 to 2016. The sample size ranges from 100 to 3217. Totally5019parturient women were included in these studies, and the puerperal in ElCS and EmCS group were 1390 and 3629, respectively.

Table 1 Characteristic of the included studies
Full size table

Quality assessment

The bias table in the Review Manager 5.3 Tutorial was used to evaluate the risk of each study by applying the criteria of evaluating design-related bias. The risk of bias table in this study is present in Table 2. Due to the obvious differences between ElCS and EmCS, high risk of blinding of participants and personnel was existed for in the included studies.

Table 2 Risk of bias table in this study
Full size table

Results of meta-analysis

Meta-analysis about the rate of maternal complication

Seven of nine included studies were involved in the maternal complication of post-operation. The forest plot for the rate of maternal complication in ElCS and EmCS group is shown in Fig. 2. All these seven studies showed the statistical difference of the rate of maternal complication between ElCS and EmCS group. In addition, the meta-analysis suggested that significant difference of the rate of maternal complication in ElCS and EmCS was observed [RR = 0.43, 95% CI (0.38, 0.48), P < 0.00001; P for heterogeneity = 0.68, I 2 = 0%].

Fig. 2
figure 2

Forest plot for the rate of maternal complication in ElCS and EmCS group

Full size image

Subgroup analyses about the rate of maternal complication

Subgroup analyses were preformed according to the types of complications. The major maternal complications in ElCS and EmCS were similar, including infection of wound and respiratory infection, fever, UTI, headache, wound dehiscence, DIC, and reoperation. The forest plot for subgroup analyses is shown in Fig. 3. The combined results demonstrated that the rates of infection, fever, UTI, wound dehiscence, DIC, and reoperation of EmCS were all much higher than those of ElCS [RR = 0.44, 95% CI (0.37, 0.53), P < 0.00001; RR = 0.29, 95% CI (0.19, 0.45), P < 0.00001; RR = 0.31, 95% CI (0.23, 0.41), P < 0.00001; RR = 0.67, 95% CI (0.48, 0.95), P = 0.02; RR = 0.34, 95% CI (0.17, 0.66), P = 0.001; RR = 0.44, 95% CI (0.21, 0.93), P = 0.03, respectively], while the rate of headache between ElCS and EmCS showed no difference [RR = 1.85, 95% CI (0.80, 4.30), P = 0.15].

Fig. 3
figure 3

Forest plot for subgroup analyses of the rate of maternal complication in ElCS and EmCS group

Full size image

Meta-analysis about the rate of fetal complication

These three included studies which involve in the fetal complication of post-operation are shown in Fig. 4. Despite Najam suggested that difference of the rate of fetal complication between ElCS and EmCS was not significant, the overall result indicated that the rate of fetal complication in EmCS was higher than that of ElCS [RR = 0.36, 95% CI (0.24, 0.55), P < 0.00001; P for heterogeneity = 0.28, I 2 = 22%].

Fig. 4
figure 4

Forest plot for the rate of fetal complication in ElCS and EmCS group

Full size image

Meta-analysis about the infant mortality rate

Four studies were involved in the fetal outcome, as shown in Fig. 5. Souksyna reported that the infant mortality rate in EmCS was similar to that of ElCS (P > 0.05), while the combined result suggested that the infant mortality rate of EmCS was also much larger than that of ElCS [RR = 0.16, 95% CI (0.10, 0.26), P < 0.00001; P for heterogeneity = 0.76, I 2 = 0%].

Fig. 5
figure 5

Forest plot for the infant mortality rate in ElCS and EmCS group

Full size image

Bias analysis

According to the results above, low heterogeneities of meta-analyses about the rate of maternal complication, fetal complication, and infant mortality rate were observed (I 2 = 0, 22, and 0%, respectively), and fixed-effect models were chosen.

Funnel plots for the studies about the maternal complication, fetal complication, and fetal outcome were performed (Figs. 6, 7, 8), and the Egger’s tests of different parameters are presented in Table 3, which showed that no publication bias was observed in these meta-analyses (P > 0.05).

Fig. 6
figure 6

Funnel plot of studies involved in the maternal complication

Full size image
Fig. 7
figure 7

Funnel plot of studies involved in the fetal complication

Full size image
Fig. 8
figure 8

Funnel plot of studies involved in the fetal outcome

Full size image
Table 3 Egger’s tests of different parameters
Full size table

Discussion

Cesarean section rates have increased dramatically in recent years. Due to economical aspects in terms of health care budgets and customs, the cesarean rates vary in different countries, even in different regions. The CS rate of US was 32.8% in 2010 [27]. In India, cesarean rates ranged from 8 to 36% [28]. Cesarean section was used as a lifesaving operation of the mothers and because of the poor facilities and technology, the rate of complications reached 50 to 70% in the past decades. With the widely use of spectrum antibiotics, advanced blood transfusion facilities, and improved surgical techniques, the morbidity and mortality of mother and newborn with this procedure has come down considerably. Nowadays, cesarean section has been one of the most widely used procedures, even at some points, it has been abused. Though the mortality and morbidity of pregnant and fetuses is significantly decreased, it is still relatively high. The increasing rise of cesarean sections has attracted the attention of profession and public, and some gynecologists begin to discuss the necessity of cesarean section. WHO has recommended that cesarean section should only be done when it is necessary [29].

In this study, we compared that the rate of maternal and fetal complications between ElCS and EmCS for the previous has reported that elective cesarean section may reduce neonatal complications [30]. The articles included in our studies contained almost all types of maternal and fetal complications. The meta-analysis about the rate of maternal complication suggested that the morbidity of ElCS is quite lower than that of EmCS. The related risk of different complications varies. Except the headache of mother, other incidence of maternal complications including infection, fever, UTI, wound dehiscence, DIC, and reoperation is more common in EmCS compared with ElCS. These results may attribute to the longer preparation time, better surgical preparation of obstetricians, and also better condition of pregnant women. The headache of mother after the surgery may mainly be caused by anaesthesia, which is irrelevant to the types of cesarean section. Similarly, lower rate of fetal complication in elective cesarean sections was observed compared with emergency cesarean sections.

Except the complications of mother and newborn with cesarean section, fetal morbidity is another important issue. As a study in the developed country has reported, the infant mortality rate of cesarean sections is about 13 per 100,000, while the rate of vaginal birth is only 3.5 per 100,000, which is almost a quarter of the former [31]. Choate [32] et al. have suggested that compared with emergency cesarean section, elective CS has some advantages on fetal morbidity. In our studies, it has been shown that the risk of infant death is much greater with EmCS compared with ElCS.

Despite the fact that the same indications were observed in both elective and emergency groups, the proportions of symptoms are various. The indications of EmCS are usually emergent and critical, which would affect the occurrence of complications. In the results, the pure event rates of maternal complication were 23.3% (273/1172) in ElCS and 55.2% (1709/3094) in EmCS. The combined rates of fetal complication in ElCS and EmCS were 8.3% (22/265) and 20.2% (134/665), and rates of infant mortality were 1.7% (18/1035) and 9.8% (319/3248), respectively. Though the results showed the better outcomes of ElCS, the complications of both ElCS and EmCS were relatively high. One of the possible reasons was that some slight complications including headache were took into account. In addition, the week of gestation and decision-to-delivery interval (DDI) could also influence the prognosis. As long as the gestational age is more than 37 weeks or the DDI is less than 30 min, detrimental post-operative effects may be decreased, especially for fetuses [33,34,35].

In the present study, low heterogeneities of meta-analyses were obtained, and according to the funnel plots and Egger’s test, no publication bias was observed, which would support our results better. Although this study suggests that emergency cesarean sections showed significantly higher maternal and fetal complications than elective cesarean sections, there are some limitations that should be avoided. First, because of the particularity of the management, high risk of blinding of participants and personnel might be existed. The previous studies have pointed that ElCS may be more common in the urban, while EmCS may be more common in the rural [7]. Due to the better facilities and care in the hospital, the results may be influenced. Besides EmCS was usually applied in emergency situations, the status of the baby is bad originally, so it is not surprising that negative results are observed. In this study, we got some positive results, but some studies had relatively poor quality and a few studies included were published in internationally leading journals about obstetrics and gynecology, which indicates a need for further well-designed and prospective studies.

Conclusion

It was suggested that both elective cesarean section and emergency cesarean section cause certain complications to the mother and the fetuses. The incidences of maternal and fetal complications were relatively higher in EmCS than ElCS, and considerable care should be still required to provide and reduce the rates of maternal and fetal morbidity and mortality.