Trends in Vaginal Delivery and Cesarean Section–Part I

Table 17: Logistic regression for Early Onset Neonatal Sepsis (EONS) by vaginal and cesarean section 2015- ‘17.

Sex distribution

Among consecutive live births there was almost equal distribution of 49.98% (n=1288/2577) males to 50% (n=1,289/2577) females a difference of 0.1%. However, among vaginal deliveries more 51.7% (n=746/1433) females as opposed to less 48.7% (n=697/3 males. Significantly more males 52.1% (n=591/1134) among cesarean section as opposed to females 47.88% (n=543/1134) born by cesarean section. The distribution of male and female birth by vaginal delivery and cesarean section seen in (Figure 9).    

Figure 19: Sex distribution in vaginal delivery and cesarean section 2015-17.

Discussion

The incidence of cesarean section increased dramatically threefold to 42.1% noted in 2015-’17 cohort compared to only 13.2% during 1983. The overall cesarean section rate in India is 21.5%, however it varies from state to state with perinatal mortality rate (PMR) of 18.97‰ in 2022 [5]. Upward trend is also observed world-wide, United States reported an increase to 32.1% in 2022 from 22.7% in 1996 with one in three women giving birth by cesarean section and 31.2% were primigravidae, however, the rapid increase in cesarean birth rates from 1996 to 2022 without clear evidence of concomitant decreases in maternal or neonatal morbidity or mortality raises significant concern that cesarean delivery is overused [18, 19]. The 2021 PMR in US being 5.5‰ in declining from 30‰ in the fifties [20]. Similarly, in UK the cesarean section rate is 31% in 2022 but latest rates are inching towards 42% with most 28% in age group 25-34 years opting for Cesarean section with around 16% elective section and the PMR being 5.04‰ [21].

The perinatal mortality rate in 1983 cohort was 33.4‰ for vaginal delivery to high 45.3‰ for cesarean section. A gradual increase in vaginal delivery from 50% in primigravida to 85% for 5+ multi gravida was noted with corresponding increase in PMR from 50.2‰ to 86% for 5+ multi gravida in 1983 cohort. In contrast incidence of cesarean section in 1983 cohort was 18.3% in primigravida decreased to 7% in 5+ multigravida associated with dramatic increase in PMR from 57.8‰ for primigravidae to 230‰ in 5+gravida indicating grave risks in multigravidas. While third gravida mothers in 1983 cohort registered low PMR 19.5‰ for vaginal delivery and 25.6‰ for cesarean section [22].

The incidence of births in relation to gravida between 2015-’17 cohort and 1983 cohort revealed almost equal distribution 32% and 30 % respectively for primigravida subsequently dipped to 22.9% in 1983 with a peak of 27.3% for third gravida mothers in 1983 cohort while 2015-’17 cohort showed steady decline with increasing parity. Indicating a demographic shift from large family in 1983 to small family norm with one to two children in 2015-’17.

However, majority 32% in 2015-’17 cohort were primigravida of whom 55% had vaginal delivery to 45% cesarean section. Second gravidas in 30% most 57.6% had vaginal delivery to 42.3% cesarean section. While third gravida mothers 21.9% had almost equal 50.9% vaginal delivery to peak 49% cesarean section. Fourth gravida comprising 10.3% had 59% vaginal delivery to 41% cesarean section. Low incidence of 5.9% multi-5+ gravida mothers had maximum 60.2% vaginal delivery to lower 39.8% cesarean section. Contrasted sharply to 1983 cohort with 30% primigravida mothers who had high 97.6% vaginal delivery to 2.3% cesarean section. Among 22.9%, second gravida mothers, 81.5% had vaginal delivery to peak 18.5% cesarean section. For 27.3% third gravida mothers 93% had vaginal delivery to 7% cesarean section. Among 12% fourth gravida mothers 93% had vaginal delivery to 7% cesarean section. While 7.6%, multi para 5+, 94% had vaginal delivery and 6% cesarean section. Thus, cesarean section remained above 40% regardless of gravida in 2015-’17 cohort but decreased with increasing gravida in 1983 cohort.

Peak gestation 30% births in third gravida mothers occurred at 38 weeks, indicating better maternal and neonatal outcome, followed by 27% second gravida and 22.5% fourth gravida mothers at 38 weeks gestation, contrasted to majority 27.6% primigravida peaked later at 39 weeks with difficult vaginal delivery with resort to emergency cesarean section. Multigravida 5+ show biphasic peaks of 26.5% at 37 weeks and 22.5% at 39 weeks gestation in 2015-’17 cohort.

Teenagers comprised 8.6% during 2015-’17, most 61.6% had vaginal delivery to 38.3% cesarean section. Young 38.9% mothers aged 20-24 years, 61.8% had vaginal delivery to 38.2% cesarean section, while 34.7% older 25-29 years mothers had similar distribution of 51.7% vaginal delivery to 48.3% cesarean section. Similarly, 15.9% aged 30-35 years, nearly equal 51% vaginal delivery to 49% cesarean sections, while 1.8% elderly mothers ≥35 years had slightly higher incidence 52% cesarean section compared to 48% vaginal delivery. Thus, older mothers ≥ 25 years were subjected to slightly more cesarean sections than younger mothers.

In contrast 13%, teenaged mothers in 1983, majority 89.3% had vaginal delivery to 10.7% cesarean section, while 15.9% aged 20-24 years had 88.8% vaginal delivery to 11.2% cesarean section, contrasted to peak 50% older 25-29 years mothers who had 87.6% vaginal delivery to 12.4% cesarean section, however mothers aged 30-34 years comprised 16.2%, more 80.7% had vaginal delivery to 19.3% cesarean section. While among 4.8% elderly mothers aged ≥35 years, 79.6% were vaginal delivery with peak 20.4% cesarean section.

The percentage distribution of births in relation to maternal age and mode of delivery in 1983 cohort revealed that nearly 40% of mothers in the age group 25 to 29 years had the highest incidence 73.3% of cesarean section. High PMR was noted for cesarean section of 40.8‰ in teenagers decreased to a minimum 17.4‰ for 20-24 years; thereafter increase to 44.8‰ in 25-29 years age group, to 45.8‰ for 30-34 years to a high 60.6‰ above 35 years mothers. In contrast PMR for vaginal delivery ranged from 57.1‰ in teenagers, to 36.8‰ for 20-24 years with least 27.5‰ in 25-29 years age group, thereafter increased to 59.6‰ for 30-34 years and to 66.7‰ for 35 years and above. The incidence of cesarean section increased with maternal age from 10.7% in teenagers to 20% in those above 35 years associated with high PMR ranging from 50-70. Risk for Cesarean section increased with maternal age in 1983 cohort from 10% to 20% while incidence of vaginal delivery was maximum 73% for 25-29 years increased with maternal age. Thus, increase maternal age is at increased risk for cesarean section [23].

Thus higher 43% cesarean section was noted for mothers aged 20-24 years and 34% in 25-29 years, while teenage and older mothers above 30 years also had higher incidence of cesarean section compared to vaginal delivery. Thus, older mothers were more subjected to cesarean sections. Logistic Regression for cesarean section and vaginal delivery between young mothers below and above 25 years was highly statistically significant OR 0.65 [95% CI 0.55,0.76]; p<0.001. In fact, older mothers had higher incidence cesarean section when compared to younger mothers below 24 years who had higher 52% vaginal delivery to 34.7% cesarean section. Other studies show increased cesarean section rates 43.1% above 40 years and only 11.6% younger than 25 years [8, 23].

The comparison of peak delivery in 2015-’17 revealed 38.9% were young mothers aged 20-24 years followed by 34.7% in mothers aged 25-29 years with subsequent progressive decline of older mothers, contrasted to peak 50% or half of all births to older mothers aged 25-29 years with 15.9% and 16.2% for maternal ages 20-24 years and 30-34 years. Indicating that in recent times there is a demographic shift of small family norm in younger mothers.

Obstetrical complication of pre-labor rupture of membranes PROM) is more frequent in developing countries with increased risk for cesarean section is an important problem in obstetric practice. In the present study overall PROM occurred in 7.2% consecutive live births in 2015-’17 cohort, however, among vaginal delivery PROM was only 6% compared to higher 9% for caesarean sections as PROM is often an indication due to prolonged labor, fetal distress, malpresentation, cephalopelvic disproportion, failed induction, birth asphyxia, sepsis etc. Logistic Regression of PROM between cesarean section and vaginal delivery being highly statistically significant OR 1.53 [95% CI 1.08, 1. 1.13, 2.06]; p=0.005.  PROM being an indication for cesarean section more so if meconium-stained liquor and fetal distress.

PROM is abnormal prior to the onset of clinically apparent labor contractions while spontaneous rupture of membranes (ROM) is a normal component after onset of labor. Etiology of PROM is probably infection and may be preventable with proper antenatal screening and treating of genito-urinary infections etc. Literature also reports that PROM is associated with an increased risk of cesarean delivery common indications being fetal distress, malpresentation, cephalopelvic disproportion and failed induction [24], another study reported high 28% PROM among cesarean section in Iran [25]  similarly also West Bengal 26.6% [26]  Common maternal complications of PROM are chorioamnionitis, retained placenta, endomyometritis, wound infection, pelvic abscess, bacteremia and postpartum hemorrhage while early onset neonatal sepsis has serious consequences [27].

The management of PROM includes immediate labor induction in pregnant woman at term in absence of other maternal and fetal contraindications however pre-term PROM is more complex and carries risk of prematurity and other related fetal complications [28, 29]. However, planned early birth resulted in decrease risk of maternal infections such as chorioamnionitis and/or endometritis than expectant management following term prelabour rupture of membranes. Randomized controlled trials of planned early birth are more likely to have their labor induced compared with expectant management in women with PROM at 37 weeks' gestation or later included ten trials assessing intravenous oxytocin; twelve trials assessed prostaglandins (six trials in the form of vaginal prostaglandin E2 and six as oral, sublingual or vaginal misoprostol) without an apparent increased risk of caesarean section [30].

Gestational Diabetes Mellitus with overall incidence of 5.2% among 2609 live births, contrasted 8% in cesarean section being nearly three times higher to 3% vaginal delivery in 2015-’17 cohort. Thus, logistic regression of GDM between cesarean section to vaginal delivery is highly statistically significant OR 2.78 [95% CI 1.93,4.02]; p<0.001. Though vaginal delivery is possible the increased risk of a large baby with shoulder dystocia, perineal laceration, primary postpartum hemorrhage (PPH), sepsis, or undetected genitourinary tract infections predisposes to early onset neonatal sepsis, fetal distress etc. are often indication for cesarean section results in improved maternal and neonatal outcome [31, 32].

Pregnancy Induced Hypertension (PIH) overall incidence of 5.8% had high 8% among Cesarean section as compared to one-half of 4% in vaginal delivery was highly statistically significant p<0.001 in the 2015-’17 cohort. PIH defined as systolic blood pressure ≥140 mmhg or diastolic blood pressure ≥90 mmhg or both after 20 weeks of gestation and broadly classified as gestational hypertension, proteinuria ≥300mg/24 hours or protein/creatinine ratio ≥0.3mg/dl, pedal edema as pre-eclampsia with convulsions as eclampsia. Severe hypertension increases mother’s risk of cardiac failure, heart attack, renal failure and cerebrovascular accidents, in addition fetus is at risk for poor placental transfer of oxygen, growth restriction, preterm birth, placental abruption, stillbirth and neonatal death and a main cause of maternal mortality if appropriate preventive measures are not undertaken. Complications like seizures (eclampsia), placental abruption and fetal distress or even death due to placental dysfunction during vaginal delivery can be mitigated, as the only cure for preeclampsia is birth of baby [33].

 The overall incidence of pregnancy Induced Hypertension (PIH) in 2015-’17 cohort was 5.8%. Low incidence of 4% by vaginal delivery contrasted with twice higher 8% in cesarean section being highly statistically significant, OR 2.09 [95% CI 1.49, 2.93]; p<0.001. Early delivery by cesarean section preferably elective section as opposed to emergency section is safer for both mother and baby. Thus, PIH significantly increases like hood of cesarean section compared to vaginal delivery with potential for early induction of labor [33].

Neonatal factor of birthweight among total 2584 births, majority 38% weighed between 2500-2599g, with 57% vaginal delivery to 42.4% caesarean section, similarly also 34% weighing 3000-3499g, also 57.3% were vaginal delivery to 42% caesarean section, however, increasing birthweight 3500-3999g in 7.3%, majority 59.6% were cesarean section contrasted to 41.5% vaginal delivery. Similarly, 0.8% with ≥ 4000g had nearly three quarters 71.4% cesarean section to 28.5%. vaginal delivery. Indicating increased birthweight causing undetected CPD with fetal distress resulted in obstetric surgical intervention. Thus, cesarean section was more common in larger babies weighing >3500g usually due cephalo-pelvic disproportion with macrosomic fetuses presenting with prolonged labor, fetal distress with resort to cesarean section However low birth weights below 2499g had almost equal vaginal delivery and cesarean section rates but not statistically significant.

In 1983 cohort most 42.9% weighed 2500-2999g, next 22.6% in higher 3000-3499g, followed by 21.5% with 2000-2499g contrasted to almost biphasic pattern of 38% and 34% in 2500-2999g and 3000-3499g birthweight category in 2015-’17 cohort indicating improved nutrition in recent times with higher birthweight compared to 22.6% in 1983 in 3000-3499g category.

Gestation had significant influence on outcome on mode of delivery, most 30% cesarean section, peaked at 38 weeks with 20.7% at 39 weeks, while 19.6% had preterm 36 weeks gestation. In contrast peak 30% vaginal delivery occurred at 39 weeks and 27% at 38 weeks with 19% at 40 weeks, indicating difficult vaginal delivery due to increase fetal weight gain due to prolonged gestation. The mean gestation in 1983 cohort for vaginal delivery was 38.3 weeks, S.D 2.42 while cesarean section was 37.94, weeks, SD 2.48. The, 50th% being 38.6 and 38.2 weeks for vaginal delivery and cesarean section resp. while instrumental delivery, vacuum extraction and Outlet forceps applied late during prolonged traumatic vaginal to cut short second stage was at later 38.4 weeks and 38.75 weeks respectively with 50th % being 39 weeks for both. Logistic regression in 2015-’17 cohort among 15% preterm ≥36 weeks by cesarean section to 9.5% vaginal delivery contrasted to 90.5% term newborns by vaginal delivery to 85% cesarean section being highly statistically significant, OR 1.67 [95% CI 1.31, 2.14]; p<0.001. Thus, low birthweight is 1.24-fold higher to normal birthweight as well as preterm gestation have higher chances for cesarean section due to potential complications of higher risks for both baby and mother complicated by PIH, GDM, sepsis etc. [34, 35]

 Neonatal complications among newborns by vaginal delivery was 22.6% majority 77.3% being healthy, contrasted to high 46% morbidity in cesarean section, as fetal distress is a common indication for emergency section is highly statistically significant OR 2.89 [95% CI 2.44, 3.42]; p<0.001.Study has reported high 69% neonatal mortality in cesarean section with no prior labor complications or procedures when compared planned vaginal delivery assumes importance given the rapid increase in the number of primary cesarean sections without a reported medical indication [36]. Maternal and neonatal adverse outcomes were more so in emergency operative deliveries including elective and emergency cesarean section, associated with three times moderate blood loss compared to unassisted vaginal delivery and twice as likely in operative vaginal delivery [37]. The risk of shoulder dystocia associated with increased birthweight, diabetes, induction of labor, use of epidural analgesia at delivery, prolonged labor, forceps-assisted and vacuum-assisted delivery, parity and gestation but not with post-term delivery reported in Norway [38]. Thus, both maternal and neonatal morbidity and mortality were higher in cesarean section rather than vaginal delivery [37]. Neonatal complication by cesarean section compared to vaginal delivery was highly statistically significant, OR 2.89 [95% CI 2.44, 3.42]; p<0.001 in 2015-’17 cohort.

The overall incidence of birth asphyxia was 20% among 2750 consecutive live births, however incidence of birth asphyxia was low 11.4% for vaginal delivery with 88.5% healthy newborns, contrasts to cesarean sections with high 30% asphyxiated newborns. Thus, birth asphyxia being three times higher in cesarean section compared to vaginal delivery was highly statistically significant OR 3.29 [95% CI 2.68, 4.04]; p<0.001 in 2015-’17 cohort, common indication for cesarean section often being fetal distress.

The incidence of early onset neonatal sepsis was 8.7% for total live births, however high incidence of 10.3% noted among cesarean section compared to 7.4% vaginal delivery, being statistically significant OR 1.42 [95% CI 1.08, 1.86]; p<0.01. An almost equal sex distribution, male to female ratio of 1:1 with slightly more 52.1% males born by cesarean section as opposed to 51.7% more females by vaginal delivery.

Cesarean section also increases adverse neonatal outcomes such as neonatal intensive care unit admission, including perinatal deaths with higher 1.77 per 1,000 live births 1.77 per 1,000 live births neonatal mortality in cesarean section contrasted to 0.62‰ in vaginal delivery [39]. In fact, cesarean section with no labor complications or procedures has a 69 percent higher risk more so in emergency operative deliveries than planned vaginal deliveries is of importance. Moderate blood loss was three times higher in elective and emergency cesarean section than in unassisted vaginal delivery and twice as likely in operative vaginal delivery. Therefore, cesarean section should only be practiced when conditions clearly demand it, given the recent rapid increase in the number of primary cesarean deliveries without a reported medical indication as well as relationship between cesarean delivery rate and high maternal and neonatal mortality [40].

Usually, labor is heralded by rupture of membranes and/or onset of uterine contractions initially occasional gradually increases both in intensity and frequency. Labor is divided into three stages: first, second and third stage, though fourth stage may also be included. The first stage is further subdivided into latent and active phase [41]. False labor pains or spurious labor occur more common in primigravida usually appearing one or two weeks prior to onset of true labor pain, or a few days earlier in multipara. prelabor or “lightening” occurs when the head sinks into the pelvic outlet or gets engaged. False labor pains are distinguished by its dull, continuous pain or discomfort usually confined to the lower abdomen and unrelated to hardening of the uterus with no effect on dilation of the cervix, usually relieved by sedation or enema. Often uterine contraction in ethnic Asian between 34-37 weeks of pregnancy is considered as ‘false labor pains and pregnancy prolonged to 40 weeks EDD, however labor be allowed to progress with delivery of small, healthy baby, who after birth will feed avidly and gain extra uterine weight, instead of intrauterine weight gain predisposing to difficult vaginal delivery with cephalopelvic disproportion leading to emergency cesarean section with indication of fetal distress.

The latent phase or early labor starts with maternal perception of regular contractions causing effacement the cervix which gradually effaces or thins out and dilates from 1 to 4 cm. normal duration varies from 8– to 12 hours and prolonged when it exceeds 20 hours in primiparous and 14 hours in multiparous women. On average, active labor usually lasts about four to eight hours cervical dilates normally from about 4 to 10 centimeters or about 1-1.5 cm every hour.

Cervical dilation occurs as a result of uterine contractions and the counter pressure applied by the bag of membranes and the presenting part. A well flexed fetal head closely applied to the cervix favors efficient dilation and pressure applied evenly to the cervix causes the uterine fundus to respond by contractions. Cervix will not dilate until effacement is complete. Effacement is the inclusion of the cervical canal into the lower segment; this may usually occur late in pregnancy or after labor begins. In primigravida the cervix will not dilate until effacement is complete. In multigravida effacement and dilation may occur simultaneously.

The active phase has a more rapid rate of 1-1.5 cm cervical dilation per hour. However, an interval of arrest of 4 hours was significant only after 6 cm dilation as cervical dilation is not related to time. Abnormalities of active phase labor include protraction disorders with slower progress than normal and cervical dilatation <1.2 cm/h in primigravida and <1.5 cm/h in multigravida or arrest with no cervical change for 2 hours or more in the presence of adequate uterine contractions and cervical dilation of at least 4 cm. However, from 4–6 cm both primigravida and multigravida dilated at essentially the same rate but beyond 6 cm, multiparous women dilated more rapidly. The maximal slope in the rate of change of cervical dilation over time in active phase often does not start until at least 6 cm, full dilation of cervix equates to about 10 cm diameter [42]. 

Diagnosis of failure to progress is the most common indication for intrapartum cesareans section based on assessment of cervical dilation and station over time and fetal descent earlier according to labor curves of Friedman with cervical dilation to time derived from mothers with spontaneous onset of labor however with induction of labor, new labor curves of dilation and station improve the accuracy of predicting labor progress. Two labor disorders arrest of dilation and arrest of descent are primary indication in nearly 50% of all intrapartum cesarean section however not just time alone though women with labor dystocia may deliver vaginally a longer first stage of labor is associated with adverse maternal and neonatal outcome.

The last part of active labor when the cervix dilates from 8 to 10 centimeters is called transition phase because it marks the shift to the second stage of labor. pitocin generally speeds up the active phase, while epidural anesthesia, tend to make it last longer. The cervix finishes dilating and makes the transition from opening to pushing. Contractions are now powerful and efficient so this phase is usually short, less than one hour with full cervical dilation and ends with the birth of the baby has two phases, propulsive phase, fetus moves down the birth canal due to the pressure exerted by the contracting uterus referred to as the “pushing” phase when “crowning” occurs and the expulsive phase with delivery of the baby.

Thus, increasing rate of cesarean delivery has significantly decreased the rates of operative vaginal deliveries viz vacuum or forceps and in low-risk pregnancies, cesarean section poses greater risk of maternal morbidity and mortality compared to vaginal delivery as placenta previa increases threefold from one prior cesarean section to three or more prior cesarean section and further complicated with around 40% placenta accrete [43]. Though prolonged labor is high in vaginal delivery, wound infection, surgical injury, maternal death was high in cesarean section, particularly when performed in labor however postpartum hemorrhage occurred regardless of mode of delivery [37]. Cesarean sections are absolutely critical to saving infant lives where vaginal delivery pose risks, though unnecessary surgical procedure can be harmful, both to mother and baby [40, 43].

The average Asian woman is comparatively small when compared to the tall, well-built Caucasian women.  In the U.S., only 5 % of mothers had pregnancy weight less than 45.5 kg and 16 % less than 50 kg, compared to 37 % and 68 % of Indian women who weighed less than 46 kg and 51 kg respectively [45].  Correlation between “small’ women and high perinatal loss is well documented.  Studies have shown that those weighing 45 to 50 kg had a perinatal mortality of 60%. While in those weighing above 52 kg the mortality it was only 7.5 % [46, 47]. The outcome of labor depends on the fetal weight, often small Asian women have small babies with peak 28.1% delivery at 38 weeks, Asian Due Date (ADD) ideally should be at 38 weeks term gestation. Thus, delivery even prior to ADD as early as 34-37 weeks with spontaneous onset of uterine contractions though often termed as false labor pains should be allowed to progress with birth of a healthy small baby and mother instead of prolonging pregnancy to EDD or 40 weeks gestation, well suited for ethnic Caucasian population with peak delivery 31% at 41 weeks gestation [48-50].

Other studies in the west have also noted risks of maternal morbidity such as chorioamnionitis, endometritis, wound infection, uterine atony and/or blood transfusion and cesarean delivery significantly beyond 39 weeks however adverse neonatal outcomes included death, respiratory distress syndrome (RDS), transient tachypnea of newborn (TTN), seizure, sepsis, intraventricular hemorrhage (IVH), hypoglycemia, intubation and ventilator support, 5-min Apgar score ≤3, hypoxic ischemic encephalopathy (HIE) and neonatal ICU admission  though not statistically significant if delivered after 39 weeks [51]. While cesarean delivery is firmly established as the safest route of delivery but low-risk, cesarean delivery poses greater risk of maternal morbidity and mortality than vaginal delivery it is important to assess indication between cesarean and vaginal delivery to prevent overuse of cesarean delivery, particularly primary cesarean delivery [52, 53].

Thus, delivery at 40 weeks gestation proves detrimental to the small Asian fetus with increased mortality [22], hence delivery at 38 weeks term gestation at ADD has best outcome for both mother and baby. Onset of spontaneous contractions from 34 weeks upto 38 weeks, labor should be allowed to progress or induction at 38 weeks [54], facilitating vaginal delivery of a small healthy newborn who after birth will feed avidly and gain extrauterine weight, recommended, as opposed to intrauterine weight gain by prolonging pregnancy up to 40-41 weeks gestation fraught with complications and high maternal and neonatal morbidity and mortality [55].

Conclusion

Rising 42.1% cesarean section rate noted in 2015-’17 from low 13.2% during 1983, high risk factors for cesarean section include primigravida, older mothers ≥25 years (p<0.001), obstetric complications of PROM (p=0.005), GDM (p=0.005), PIH (p<0.001), neonatal factors of prematurity ≤36 weeks (p<0.001) and low birth weight, neonatal complications 46% (p<0.001), birth asphyxia 30% (p<0.001), neonatal sepsis 11% (p<0.001) including male gender.  Though peak 30% cesarean section mainly elective took place at 38 weeks gestation, peak 30% vaginal delivery occurred later at 39 weeks gestation. Hence it is recommended that vaginal delivery at 38 weeks term gestation will improve outcome for both mother and baby.

References

1. WHO Caesarean section rates continue to rise, amid growing inequalities in access.
2. Trends and projections of caesarean section rates – BMJ Global Health.
3. Cesarean sections in OECD countries 2018| Statista
4. Yong HU, Hong Shen, Landon MB. (2017) Optimal timing for elective caesarean delivery in a Chinese population: a large hospital-based retrospective cohort study in Shanghai. BMJ Open. 7(6): e014659
5. National Family health survey (NFHS-5).
6. World Health Organization. WHO/MPS/07; 0. Geneva: WHO; 2007. WHO Recommended Interventions for Improving Maternal and Newborn Health
7. World Health Organization. (2006) pregnancy, Childbirth, postpartum and Newborn Care: A Guide for Essential practice. Geneva: WHO. 
8. Mazzoni A, Althabe F, Liu NH, Bonotti AM, Gibbons L, et al. (2011) Belizan JM. Women’s preference for caesarean section: a systematic review and meta-analysis of observational studies. BJOG. 118(4):391-9. 
9. Ali M, Hafeez R, Ahmad M. (2005) Maternal and fetal outcome; comparison between emergency caesarean section versus elective caesarean section. Prof Med J. 12(1):32-9. 
10. Kim G, Bae J, Kim MJ. (2020) Delayed establishment of gut microbiota in infants delivered by cesarean section. Front Microbiol. 11:2099 
11.  Blustein J, Liu J. (2015) Time to consider the risks of cesarean delivery for long term child health BMJ. 350:h2410.
12. Kimm, Sue YS. (2004) Fetal origins of adult disease: The Barker hypothesis revisited – 2004.Current Opinion in Endocrinology & Diabetes. 11(4): p192-196.
13. Stein CE, Fall CH, Kumaran K Osmond C, Cox C, Barker DJP. (1996) Fetal growth and coronary heart disease in South India. Lancet. 348(9037):1269-73
14. Eriksson JG, Forsen TJ, Osmond C, Barker DJP. (2003) Pathways of infant and childhood growth that led to type of diabetes. Diabetic care. 26(11):3006-10.
15. Minkoff H. (2012) Fear of litigation and cesarean section rates Semin Perinatol. 36(5):390-4
16. Dubay L, Kaestner R, Waidmann T. (1999) The impact of malpractice fears on cesarean section rates. J Health Econ. 18(4):491-522. 
17. Leitch CR, Walker JJ. (1998) The rise in caesarean section rate: the same indications but a lower threshold. Br J Obstet Gynaecol. 105(6):621-6.
18. Discroll AK, Osterman MJK, Hamilton BE, Valenzuela Cp, Marin JA. (2022) Quarterly provisional estimates for selected birth indicators, Quarter 4, 2021. National Center for Health Statistics. National Vital Statistics System, Vital Statistics Rapid Release Program.
19. Valenzuela Cp, Gregory ECW, Martin JA. (2023) Perinatal Mortality in the United States, 2020-2021. NCHS Data Brief. 489:1-8.
20. UK C-Section Rates 2023: Stats, Perspectives & Guidance 2023 Commissioned by Dr. Chrissie Yu MBBS (Lond) MD (Lond) FRCOG, Consultant Obstetrician & Specialist in Fetal-Maternal Medicine
21. Christopher GL. (2023) Mode of delivery on perinatal outcome.  Recent advances in Perinatology with special reference to ethnicity.
22. Ecker JL, Chen KT, Cohen Ap, Riley LE Liberman ES. (2001) Increased risk of cesarean delivery with advancing maternal age: indications and associated factors in nulliparous women. Am L Obstet Gynecol. 185(4):883-887
23. Hussain. (2013) Early rupture of membrane a risk factor for cesarean section in term pregnancy. FASCICULA XVII nr. 2 
24. Eslamian L, Asadi M. (2002) The cesarean section rate in cases with PROM. Acta Medica Iranica. 40:2.  
25. Chakraborty B. (2013) Outcome of prelabor rupture of membranes in a tertiary care center in west Bengal. Indian J Clin Pract. 24(7)
26. Kunze M. (2011) Intrapartum management of premature rupture of membranes: effect on cesarean delivery rate. Obstet Gynecol. 118(6):1247-54. 
27. Caughey AB. (2008) Contemporary diagnosis and management of preterm premature rupture of membranes. Rev Obstet Gynecol. 1(1):11-22. 
28.  Keirse MJ, Ohlsson A, Treffers PE, Kanhani HHH. (1989) Prelabour rupture of the membranes preterm. In: Chalmers I, Enkin M, Keirse MJ, editors. Effective care in pregnancy and childbirth. Oxford: Oxford University press. 666.
29.  Middleton P, Shepherd E, Flenady V, McBain RD, Crowther CA. (2017) planned early birth versus expectant management (waiting) for prelabour rupture of membranes at term (37 weeks or more). Cochrane Database Syst Rev. 1(1):CD005302.
30. Moses RG, Knights SJ, Lucas EM, Moses M. (2000) Gestational diabetes: is higher cesarean section inevitable. Diabetes Care. 23:15-17.
31. Overland EA, Vatten LJ, Eskild A. (2014) Pregnancy week at delivery and the risk of shoulder dystocia: a  population study of 2,014,956 deliveries. 121(1):34-41.
32. Brown MA, Magee LA, Kenny LC. (2018) Hypertensive disorders in pregnancy: ISSHP classification, diagnosis and management recommendations for international practice. Hypertension. 72:24-43.
33. Chen Y. (2016) Delivery modes and pregnancy outcomes of low-birth-weight infants in China. J Perinatol.
34. Ghahiri A, Khosravi M. (2015) Maternal and neonatal morbidity and mortality rate in cesarean section and vaginal delivery Adv Biomed Res. 4:193
35. Sharma S, Dhakal I. (2018) Cesarean vs Vaginal Delivery: An Institutional Experience. J Nepal Med Assoc 56(209):535-39
36. Kamilya G,Seal GL, Mukherji J, Bhattacharyya SK, Hazra A. Maternal mortality and cesarean delivery: An analytical observational study.
37. Nielsen KK. (2021). Migration, Gestational Diabetes and Adverse Outcome: A nation-wide study of singleton deliveries in Denmark J Clin Endocrinol Metab.
38. Molina G, Weise TG, Lipsitz SR. (2015) Relationship between cesarean delivery rate and maternal and neonatal mortality. JAMA. 314:2263-2270
39. MacDorman MF, Declercq E,Menacker F, Mallloy MH. (2006) Infant and neonatal mortality for primary cesarean and vaginal births to women with "no indicated risk," United States, 1998-2001 birth cohorts. Birth. 33(3):175-182. 
40. Normal Labor: Physiology, Evaluation and Management. National Institutes of Health (NIH).
41. Hamilton EF, Zhoroev T, WarrickpA, Tarca AL. (2024) New labor curves of dilation and station to improve the accuracy of predicting labor progress Am J Obstet Gynecol. 231 (1):1-18.
42. Gregory KD, Jackson S, Korst L, Fridman M. (2012) Cesarean versus vaginal delivery: whose risks? Whose benefits? Am J Perinatol. 29:7-18.
43. Mac Donald HM, Mulligan JS, Allen AC, Taylorp M. (1970) Neonatal Asphyxia I, Relationship of obstetric and neonatal complications and   neonatal   mortality in 38, 405 consecutive deliveries. Pediatrics. 96:898-902.
44. Malvakar DV. (1994) Maternal weight, height, and risk of poor pregnancy outcome in Ahmadabad, India. Ind Pediatr. 31:1205-1212.
45. David RJ. Differing Birth Weight among Infants of U.S.-Born Blacks, African-Born  
46. Perkins JM, Subramanian SV, Davey Smith G, Ozaltin E. (2016) Adult height, nutrition, and population health. Nutr Rev. 74(3):149-65.
47. Park GL: The duration of pregnancy. Lancet 1968; ii: 1388.
48. Miere HB. (1981) Ultrasound demonstration of an unusual fetal growth pattern in Indians Brit J Obstet & Gynecol. 88:269
49. Papiernik E. (1986) Ethnic difference in duration of pregnancy. Am Hum Biol. 13;259-256
50. Tita ATN, Lai Y, Bloom SL, Spong CY, MW, Ramin SM, et al. (2011) Timing of Delivery and Pregnancy Outcomes Among Laboring Nulliparous Women: Am J Obstet Gynecol. 206(3):239.e1–239.e8.
51. Clark SL, Belfort MA, Dildy GA, Herbst MA, Meyers JA, et al. (2008) Maternal death in the 21st century: causes, prevention, and relationship to cesarean delivery. Am J Obstet Gynecol. 199:36. e1-36.e5;91–2. 
52. Liu S, Liston RM, Joseph KS, Heaman M, Sauve R, et al. (2007) Maternal mortality and severe morbidity associated with low-risk planned cesarean delivery versus planned vaginal delivery at term. Maternal Health Study Group of the Canadian Perinatal Surveillance System. CMAJ. 176:455-60. 
53. Gülmezoglu AM, Crowther CA, Middleton P, Heatley E. (2012) Induction of labour for improving birth outcomes for women at or beyond term. Cochrane Database of Systematic Rev. 6:CD004945.
54. Bruckner TA, Cheng YW, Caughey AB. (2008) Increased neonatal mortality among normal-weight births beyond 41 weeks of gestation in California. Am J Obstet Gynecol. 199:421. e1-421.e