Full-term pregnancy is defined as a gestational age of 39 to 41 weeks; late-term pregnancy, as a gestational age of 41 to 42 weeks; and post-term pregnancy, as a gestational age of $\ge$42 weeks [1]. In pregnancies without any defined risk factors (low-risk pregnancy), delivery does not occur spontaneously at term or at gestation. When gestation is prolonged after a full-term pregnancy, perinatal morbidity and mortality rates increase [2, 3]. Thus, obstetricians recommend delivery with induction of labor (IOL) to reduce the risks of fetal morbidity and mortality. However, no consensus has been reached on the optimal timing to initiate IOL in term or post-term pregnancies [4, 5]. Previous studies have suggested that IOL during late-term pregnancy decreases the risks of fetal and maternal morbidity compared with IOL during post-term pregnancy [5, 6].

The cesarean section (CS) rate is increasing worldwide, with one in three women in the United States and four in five women in some regions of the world having undergone CS [7]. CS rates are higher in Türkiye, Egypt, and Brazil than in other countries. Many factors affect obstetricians’ decision to perform CS, such as the patient’s desire to have CS or noncompliance during labor, health laws, and defensive medicine. On the basis of data from the years 2021 and 2022, the CS and primary CS rates in live births in Türkiye were 58.4% and 57.6%, and 29.1% and 29.8%, respectively [8, 9]. However, CS is associated with maternal morbidities and a high cost and economic burden on the health system [7]. Thus, we conducted this study to determine whether the CS rate in late-term pregnancy was high in women with a cephalic fetal presentation and to identify the factors associated with the CS rate in a tertiary hospital in Türkiye.

The results showed that the total CS rate was 28.7% in the late-term pregnancies, which was lower than the annual national CS rate of 57.6%. The CS rate among the nulliparous women with late-term pregnancies was higher (44.3%) than the national primary CS rate (29.8%) [9]. The multivariate analyses revealed that being nulliparous and male fetal sex were associated with the increased CS rate. Having a prior vaginal delivery is known to enhance the likelihood of a later vaginal delivery, which explains why the CS rate was higher in the nulliparous women. Since the caesarean section rate will be higher in nulliparous than in multiparous, we think that it will not be meaningful to compare the CS rates and CS indications. A low BS indicates inefficient cervical ripening, which explains why the CS rate was higher in the pregnant women who received dinoprostone for cervical ripening before oxytocin administration.

IOL is a common practice that can also interfere with the natural processes of pregnancy and childbirth. It is often painful for women and may require epidural analgesia or operative delivery [14]. According to maternal and perinatal health data from the World Health Organization (WHO), based on approximately 300,000 births in 24 countries, IOL is performed in approximately 9.6% of deliveries. The IOL rates tend to be lower in African countries than in Asian and Latin American countries and generally higher in developed countries than in developing countries [15]. While IOL may be necessary in certain high-risk situations, it is an independent risk factor for complications that can increase the risk of fetal and maternal morbidities and mortality [16]. In studies that evaluated the risks in late- and post-term pregnancies, primiparous women have been found to have a higher risk than multiparous women [17, 18]. Furthermore, in a cohort study that compared maternal and perinatal risks according to gestational age, the adverse risks of both maternal and fetal morbidities were higher in nulliparous women than in multiparous women [19]. The results of the present study support those of previous studies that indicated that nulliparous women have a higher CS rate (44.3%), which represents fetal and maternal morbidities.

No information has been reported on the effect of fetal sex on post-term pregnancies. A recent study concluded that fetal sex did not have a significant effect on post-term pregnancy [2]. In our study, the proportion of male fetuses (45.3%) was lower than that of female fetuses (54.7%). However, having a male fetus increased the CS rate by twofold compared with having a female fetus, which could be attributed to differences in birth weight between male and female fetuses.

Late- and post-term pregnancies are associated with increased maternal morbidity, neonatal morbidity, and mortality [18, 20]. The main concern in late- and post-term pregnancies is the increased risk of intrauterine fetal death [5]. The perinatal mortality rate increases from 0.7% to 5.8% as the gestational age increases to between 37 0/7 and 43 6/7 weeks [21]. The fetal and neonatal complications in late- and post-term pregnancies include macrosomia, meconium aspiration, hypoxia due to placental insufficiency, asphyxia, oligohydramnios with related morbidity, and a low Apgar score [18, 22, 23, 24, 25]. Postmaturity syndrome has been observed in approximately 20% of post-term pregnancies. Macrosomia is defined as a birth weight $>$4000 g, and its incidence rate increases in post-term pregnancies, which leads to increases in CS and fetal and maternal morbidity rates [23, 25]. In our clinic, fetuses with an estimated weight $>$4000 g during prenatal visits were delivered via CS. Hence, the incidence rates of fetal and maternal morbidities due to macrosomia in the present study were very low. In addition, operative vaginal delivery is not usually performed in our clinic because of the risk of complications and legal issues. Thus, we prefer cesarean delivery over operative vaginal delivery, which explains the higher CS rate in our clinic.

Keulen et al. [26] reported that the CS rate in late-term pregnancy was 10.1% in a high-population (n: 1801) study. The CS rate in our study was 28.7%, much higher than that in their rate. Keulen et al. [26] also reported an operative delivery rate of approximately 10.0%. However, none of the women in our study had an operative vaginal delivery because CS is generally preferred to operative vaginal delivery in Türkiye, which explains the higher CS rate in our study than in those in other countries. Ranjbar et al. [27] reported a cesarean rate of 27.7% and an operative vaginal delivery rate of 1.3%. The fetal distress rate in their study was 82.0%, which is higher than that in our study (60.2%). The results of the previous and present studies are similar and suggest that patients and physicians from similar geographical regions have similar characteristics and attitudes toward the mode of labor induction.

The fact that this study was conducted at a single tertiary center represents an important limitation. However, we think that there is no risk of bias in the study because the study is retrospective and the treatments and procedures given to the patients in the delivery room are performed by different teams, not just a single physician.

Recent studies have indicated that the CS rate is higher in post-term than in term pregnancies [28, 29]. This finding suggests that both physicians and pregnant women have the intention for CS, as also demonstrated in our study. In our study, we tried to reveal that even if labor induction is applied in late-term pregnancies, our CS rate is still high and the factors affecting the high CS rate. We think that it will help future studies and may guide clinicians working to reduce cesarean section rates in clinics.

On the basis of the findings of this study, nulliparity, and male fetal sex were associated with an increased CS rate. These factors influence obstetricians’ decision-making process regarding the mode of delivery in late- and post-term pregnancies. The high CS rate in late-term cephalic pregnancies may be attributed to the aim of avoiding maternal and fetal morbidities. Further research is required to enhance our understanding and effective management of late- and post-term pregnancies.

The datasets analyzed in the present study are available from the corresponding author upon reasonable request.

NE and MK designed the study. NE, MK, YAM, and FEIE performed the experiments. NE and MK analyzed the data. NE and MK prepared the manuscript. All authors contributed to the editorial changes in the manuscript. All authors read and approved the final version of the manuscript. All authors have participated sufficiently in the work, and agreed to be accountable for all aspects of the work.

All subjects gave their informed consent for inclusion before they participated in the study. This study was conducted in accordance with the 1975 Declaration of Helsinki, as revised in 2008. It was approved by the ethics committee of Antalya Training and Research Hospital in 2022 (protocol No. 318).

This research received no external funding.

The authors declare no conflict of interest.