Introduction

One of the medical concerns is related to the complications of cesarean delivery (1). Although the advances in specialist knowledge and improvement in facilities have reduced the fatal and debilitating side effects of this method since its inception, the mortality rate of cesarean section (C-section) is still more than 7 times higher than that of normal delivery. Moreover, the unreasonable and unjustifiable growth of the C-section has increased the financial burden on the healthcare system of communities and has significantly increased the share of healthcare per capita in national production (2). One way to reduce the rate of C-sections is to decrease its recurrence, which accounts for about one-third of all C-sections, and its suitable alternative is a vaginal birth after cesarean (VBAC).

The selection of VBAC may seem a wise and rational decision for many women, and if these women are chosen correctly, the risk of such morbidities as postpartum hemorrhage, infection, surgical injuries, thromboembolism, hysterectomy, and even death will decrease. This matter should be taken into consideration by those who decide to have larger families and are, therefore, at risk of possible consequences of repeat C-sections, such as hysterectomy, bladder and intestines damage, blood transfusion, infection, abnormal placental implantation, placenta pervia, and placenta accreta. Moreover, in females who undergo a trial of labor after cesarean and, consequently, experience a successful vaginal delivery, the recovery period is faster and the total cost of delivery is lower than in those who choose a second cesarean (3, 4).

The rate of C-section in Iran has increased from 35% in 2000 to 56% in 2013, while slightly decreased to 50.77% in 2018 (5). Despite the high rate of C-sections in Iran, the rate of VBAC in 2018 was reported less than 1% (i.e., 0.8%) (6), while it was estimated at 13.3% in the United States in the same year. This rate was obtained at 14% and 29-36% in Australia (7, 8) and in Ireland, Germany, and Italy, respectively. In the Netherlands, Sweden, and Finland the same rate was calculated at 44-55% in 2008 (9).

The results of studies have shown that among the factors that could affect the patient's decision about performing VBAC included physician encouragement, ultimate benefits of the type of delivery, physical and psychological factors and the woman's sense of control over the decision-making process, lack of awareness of the possibility of VBAC (10), unawareness of delivery results, fear of unpleasant experiences, lack of access to positive physicians, pressure from others for the type of delivery (abstract norms), lack of self-confidence, lack of self-efficacy in the decision-making process, and maternal negative attitude (11).

Since the fear of legal issues due to the poor results of VBAC is one of its significant obstacles, knowing the results of research conducted in the field of VBAC and comparing them with those reported regarding repetitive C-section can provide the basis for evidence-based performance among healthcare providers and informed choice among healthcare recipients. In addition, access to the research background of a topic in any country provides a good research horizon for users of that topic. Despite the existence of many international studies carried out on research and international and national guidelines for the safety of VBAC, the statistics of Iran indicate that this matter is not dealt with clinically. Therefore, the present study was conducted to review the studies investigating VBAC in Iran.

Materials and Methods

This narrative review research was carried out in 2020 on the studies limited to Internet search. Detailed research was performed on studies conducted in Iran, in both Persian and English, without a time limit on the Irandoc, SID, Google Scholar, Scopus, PubMed, Web of Science Magiran, and Iran Medex databases. All Iranian articles up to October 2020 were included and the research process was conducted using Persian and English keywords of "Vaginal birth after cesarean", "Repeated C-section", "VBAC", "Trial of labor after cesarean", "TOLAC", and Iran.

The initial search was performed by both authors separately and to access all studies conducted in Iran, the type of study and time restriction were not considered. The screening of studies was performed in three stages based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses process. The required data were extracted using a checklist, including the type, time, and results of the study. To improve the research methodology and review the quality of the articles, another researcher reviewed the articles separately in terms of title, abstract, introduction, methodology, and results.

First, irrelevant studies to the subject were excluded by reviewing their title and abstract and repeated research was excluded. The inclusion criteria were English or Persian studies investigating VBAC, conducted in Iran, and full-text available, according to which the required studies were gradually entered to be reviewed. As a result, a total of 142 articles were retrieved; however, finally, according to the inclusion criteria and after removing duplicate articles, 12 full-text articles were carefully reviewed by researchers (Figure 1).

Results

The total number of reported studies on VBAC in Iran was 12 articles (8 Persian and 4 English) with a sample size of 2,969 cases, all of which were reviewed. The results of reviewed studies are summarized in Table 1. It was revealed that in all cesarean deliveries, compared to vaginal delivery, there was an increase in maternal mortality and main and important maternal complications, such as infection, bleeding, thromboembolism, and anesthesia complications. Although cesarean delivery is associated with a lower risk of fetal trauma, the rate of initial respiratory distress is higher in C-section than in VBAC (21). The examined outcomes in the present review studies include:

A- Maternal consequences

Fever: Based on the results of a study performed by Arab (2001), fever was the most common complication in both normal delivery and repeat C-section groups, although it was reported to be more common in the C-section group (7%). Bagheri (2016) reported that there was no significant difference between the two groups (P=0.529) in this regard; however, according to Yousefzadeh (2006), a higher prevalence of postpartum fever (17.88%) was observed in the repeat C-section group. Ghorashi (2004) reported fever in 0.23% of mothers in the repeat C-section group, while, no cases were reported in the VBAC.

Maternal death: The results of studies performed by Arab (2001), Yousefzadeh (2006), and Mirtimouri (2015) were indicative of no cases of maternal death followed by VBAC.

Bleeding: Based on the findings of a study performed by Bagheri (2016), bleeding was not significant in the two groups (P=0.629). The postpartum hemorrhage incidence in the VBAC group was estimated at 5.88%, 2.7%, and 2% of cases respectively in the studies carried out by Yousefzadeh (2004), Mirtimori (2015), Asgarian (2018), which were higher than in the repeat C-section. Ghorashi (2004) reported bleeding in 0.23% of mothers in the repeat C-section group, while no cases were observed in the VBAC group regarding this.

Uterine rupture: One of the most important complications in VBAC is uterine rupture, which is reported to be 1 out of 200 cases and is accompanied by such factors as the unripe cervix and the use of prostaglandins for induction of labor. The incidence probability of this complication in repeat C-sections was found to be 1 out of 4,000 cases (22). Bagheri (2016) and Yousefzadeh (2006) reported that uterine rupture occurred in 2.15% and 0.49% of women with a repeat C-section, respectively. However, Pahlavani-Sheikhi (2015) and Vatanchi (2016), respectively, reported two cases of uterine rupture associated with the trial of labor and one case of vaginal omentum prolapse following uterine rupture associated with VBAC. According to the results of a study performed by Asgarian (2018), the uterine rupture was observed in 0.7% of females who underwent trial labor.

Hysterectomy: The rate of a hysterectomy varies from 0.4 to 2.5 cases per 1,000 deliveries, and hysterectomy is performed during C-section with the most common reasons of preventing or stopping bleeding due to uterine atony or abnormal placental implantation (21). The rate of hysterectomy in the repeat C-section group was estimated at 1.05%, 0.49%, 0.9%, in the studies carried out by Bagheri (2013), Yousefzadeh (2006), Ghorashi (2004).

Constipation: Bagheri (2016) reported that constipation was significant in the normal delivery and in the repeat C-section group (16.67% and 34.73%, respectively; P=0.005). Based on the results of a study conducted by Yousefzadeh (2004), a higher prevalence of constipation was observed in the repeat C-section group (1.48%).

Flatulence: Yousefzadeh (2006) reported flatulence incidence in 6.43% of the cases in the repeat C-section group.

Cervical rupture: According to Ghorashi (2004), the cervical rupture was observed in 0.6% of cases following a VBAC.

Curettage: Ghorashi (2004) reported the 1.2% frequency of postpartum curettage for placental abruption in the normal delivery group.

Nausea and vomiting: In a study performed by Ghorashi (2004), ileus, including nausea and vomiting, were the complications that were reported only in the repeat C-section group (0.7%).

Bladder rupture: Ghorashi (2004) reported that intraoperative bladder rupture was a complication observed only in the repeat C-section group (0.46%).

B- Neonatal outcomes: Apgar score: In the studies conducted by Bagheri (2016) and Ghorashi (2004), no difference was observed in neonatal outcomes (Apgar score) in the two groups. Yousefzadeh (2006) reported that Apgar scores of less than 7 were revealed only in 1.98% of repeated C-sections.

Admission to the neonatal intensive care unit: Based on the results of a study performed by Mirtimori (2015), admission to the neonatal intensive care unit and the need for resuscitation were more common (57.1%) in the repeat C-section group (P=0.002). According to the findings of a study carried out by Asgarian (2018), 2.67% of neonates born by normal delivery needed resuscitation.

Breastfeeding: Mirtimori (2015) reported that the rate of successful breastfeeding was higher in the VBAC group (95.8%) than in the repeat C-section group (42.9%), which was significantly different (0.002).

C- Costs and length of hospitalization

It was found that the mean length of hospital stay was longer in the repeat C-section group than in the normal delivery, estimated at 2.7, 3.1, and 4.7 days in the studies performed by Arab (2001), Yousefzadeh (2004), and Ghorashi (2004), respectively. Mirtimori (2015) reported this index for 2 days, which was significantly higher than that in the VBAC group (P=0.007).

Cost of C-section: In a study conducted by Arab (1996), the cost of repeated C-section was calculated as twice the cost of VBAC.

D- Success rate and failure cause

The success chances of VBAC in cephalic pregnancy and one previous C-section were estimated at 37 weeks and more and 80-60%, respectively. Vaginal birth after cesarean is recognized as an appropriate option among 83% of cases with a history of one C-section and one natural childbirth, and 94% of individuals with a history of VBAC (23, 24). The success rates of VBAC was obtained at 91.2%, 74.3%, 47.8%, 62.9%, 85.33%, and 27.4% in the studies carried out by Mirtimori (2015), Arab (2001), Bagheri (2016), Yousefzadeh (2004), Asgarian (2018), and Ghorashi (2004), respectively. Based on the results of a study performed by Asgarian (2018), the most important causes of VBAC failure were found to be prolonged and stopped labor and fetal heart failure.

E- Obstacles and effective factors in the selection of the delivery type

In the studies carried out by Firoozi (2007, 2020), the attitude of the medical staff towards performing VBAC was reported positively and from the point of view of gynecologists and specialized students, lack of legal protection was recognized as the most important obstacle for VBAC.