Cesarean sections in a birth center

Abstracts

OBJETIVO: Estimar a prevalência de cesarianas em um centro de parto normal intra-hospitalar e identificar fatores associados. MÉTODOS: Estudo transversal com análise de prontuários de 2.441 partos assistidos em março e abril de 2005 em um centro de parto normal intra-hospitalar de São Paulo, SP. A variável dependente (tipo de parto) foi classificada como parto normal e operação cesariana. As variáveis independentes foram categorizadas em quatro grupos: demográficas; história obstétrica pregressa e atual; assistência intraparto; e resultados perinatais. A razão de prevalência e o intervalo de 95% de confiança (IC95%) foram calculados para identificar associação entre tipo de parto e variáveis maternas e do recém-nascido. RESULTADOS: Do total de partos, 14,9% foram operações cesarianas. Ter sido submetida a cesariana na gestação atual esteve associado a cesariana em gestação anterior (RP = 3,19; IC95%: 2,64;3,84), idade gestacional > 40 semanas (RP = 1,32; IC95%: 1,09;1,61), ser admitida com cervicodilatação até 4 cm (RP = 3,22; IC95%: 2,31;4,50), líquido amniótico meconial (RP = 2,5; IC95%: 2,05;3,06). Quanto ao recém-nascido, a cesariana associou-se a peso > 4kg (RP = 1,86; IC95%: 1,29;2,66). Entre as mulheres com cesariana em gestação anterior, ter também parto normal prévio foi fator de proteção para cesariana na gestação atual (RP = 0,46; IC95% 0,30;0,71). Fatores relacionados à condição fetal, como estresse fetal, líquido amniótico meconial, apresentação pélvica e macrossomia corresponderam a 47,8% (175) das indicações para a realização da cesariana; condições ligadas ao mecanismo do parto, como parada de progressão, distócia funcional e distócia de rotação totalizaram 31,3% (115) das indicações. CONCLUSÕES: A prevalência de cesariana mostrou-se dentro dos limites propostos pela Organização Mundial da Saúde. Mulheres com cesariana em gestação anterior, admitidas com até 4 cm de dilatação, idade gestacional > 40 semanas, com líquido amniótico meconial e recém-nascido > 4 kg tiveram maior risco para cesariana.

Parto normal; Cesárea; Centros Independentes de Assistência à Gravidez e ao Parto; Fatores de Risco; Estudos Transversais

ORIGINAL ARTICLES

Cesarean sections in a birth center

Caracterización de las cesáreas en centro de parto normal

Ruth Hitomi Osava^I; Flora Maria Barbosa da Silva^II; Esteban Fernandes Tuesta^III; Sonia Maria Junqueira Vasconcellos de Oliveira^IV; Maria Clara Estanislau do Amaral^V

^ICurso de Obstetrícia. Escola de Artes, Ciências e Humanidades (EACH). Universidade de São Paulo (USP). São Paulo, SP, Brasil

^IIPrograma de Pós-Graduação em Enfermagem. Escola de Enfermagem (EE). USP. São Paulo, SP, Brasil

^IIICurso de Sistemas de Informação. EACH-USP. São Paulo, SP, Brasil

^IVDepartamento de Enfermagem Materno Infantil e Psiquiátrica. EE-USP. São Paulo, SP, Brasil

^VDepartamento de Enfermagem. Faculdade de Ciências Médicas. Universidade Estadual de Campinas. Campinas, SP, Brasil

^{Correspondence}

ABSTRACT

OBJECTIVE: To estimate the prevalence of cesarean sections in a birth center of a hospital and identify factors associated.

METHODS: Cross-sectional study including medical records of 2,441 births assisted in a birth center in the city of São Paulo, southeastern Brazil, between March and April 2005. The dependent variable (type of delivery) included vaginal delivery and cesarean section. The independent variables were grouped into four categories: demographic characteristics; current and past obstetric history; intrapartum care; and perinatal outcomes. Prevalence ratios and 95% confidence intervals (95% CI) were estimated to assess the association between type of delivery and maternal and newborn variables.

RESULTS: Of all deliveries, 14.9% were cesarean sections. Cesarean section in the current pregnancy was associated with past cesarean sections (PR = 3.19, 95%CI: 2.64,3.84); gestational age >40 weeks (PR = 1.32, 95%CI: 1.09;1.61); cervical dilation of up to 4 cm on admission (PR = 3.22, 95%CI: 2.31;4.50); and meconium-stained amniotic fluid (PR = 2.5, 95%CI: 2.05;3.06). Regarding newborn characteristics cesarean section was associated with birth weight >4 kg (PR = 1.86, 95%CI: 1.29;2.66). Among women with history of past cesarean sections, having had also a prior vaginal delivery was a protective factor for cesarean section in the current pregnancy (PR = 0.46, 95%CI: 0.30;0.71). Factors related to fetal conditions including fetal stress, meconium-stained amniotic fluid, breech presentation and macrosomia accounted for 47.8% (175) while those related to the mechanism of birth including arrest disorders, functional dystocia and malposition accounted for 31.3% (115) of all indications for a cesarean section.

CONCLUSIONS: Prevalence of c-section was consistent with World Health Organization recommendations. Increased risk of c-section was associated with prior history of c-sections, cervical dilation of at least 4 cm upon admission, gestational age > 40 weeks, meconium-stained amniotic fluid, and birthweight > 4 kg.

Descriptors: Natural Childbirth. Cesarean Section. Birthing Centers. Risk Factors. Cross-Sectional Studies.

RESUMEN

OBJETIVO: Estimar la prevalencia de cesáreas en un centro de parto normal intra-hospitalario e identificar factores asociados.

MÉTODOS: Estudio transversal con análisis de prontuarios de los 2.441 partos asistidos en marzo y abril de 2005 en Centro de Parto Normal de Sao Paulo, Sureste de Brasil. La variable dependiente (tipo de parto) fue clasificada como parto normal y operación cesárea. Las variables independientes fueron categorizadas en cuatro grupos: demográficas; historia obstétrica anterior y actual; asistencia intraparto; y resultados prenatales. La tasa de prevalencia y el intervalo con 95% de confianza (IC95%) fueron calculados para identificar asociación entre tipo de parto y variables maternas y del recién nacido.

RESULTADOS: Del total de partos, 14,9% fueron operaciones cesáreas. Haber tenido parto por cesárea en la gestación actual estuvo asociada a cesárea en gestación anterior (RP=3,19; IC95%: 2,64;3,84), edad gestacional >40 semanas (RP=1,32;IC95%: 1,09;1,61), ser admitida con dilatación cervical hasta 4 cm (RP=3,22; IC95%: 2,31;4,50), liquido amniótico meconial (RP=2,5; IC95%: 2,05;3,06). con relación al recién nacido, la cesárea se asoció al peso>4kg (RP=1,86; IC 95%: 1,29;2,66). Entre las mujeres con cesárea en gestación anterior, tener también parto normal previo fue factor de protección para cesárea en la gestación actual (RP=0,46; IC95%: 0,30;0,71). Factores relacionados a la condición fetal, como estrés fetal, liquido amniótico meconial, presentación pélvica y macrosomia correspondieron a 41,8% (175) de las indicaciones para la realización de la cesárea; condiciones ligadas al mecanismo del parto, como parada de progresión, distoccia funcional y distoccia de rotación totalizaron 31,3% (115) de las indicaciones.

CONCLUSIONES: La prevalencia de cesárea se mostró dentro de los límites propuestos por la Organización Mundial de la Salud. Mayor riesgo para cesárea fue asociado a cesárea en gestación anterior, dilatación cervical hasta 4 cm, edad gestacional >40 semanas, presencia de liquido amniótico meconial y peso del recién nacido >4 kg.

Descriptores: Parto Normal. Cesárea. Centros Independientes de Asistencia al Embarazo y al Parto. Factores de Riesgo. Estudios Transversales.

INTRODUCTION

Caesarean (c-)section rates are on the rise in practically every country in the world. A study carried out in 126 countries and which included 98% of all live births in 2002 reported c-section rates ranging from 3.5% in Africa to 19.0% in Europe and 29.2% in Latin America. The worldwide rate was 15%, though distribution was irregular.⁶ A maternal and perinatal health survey conducted by the World Health Organization (WHO) in eight countries in Latin America (Argentina, Brazil, Cuba, Ecuador, Mexico, Nicaragua, Paraguay, and Peru) reported a C-section rate in public and private institutions of 33%. Of these, 49% were elective, 46% were intrapartum, and 5% were emergency c-sections.²⁴

Few countries reached c-section rates as high as Brazil, where rates in private health facilities can exceed 80%.^ª These rates have become emblematic of medical interference with the female body and its dynamics.^3,18

Maternal and neonatal morbidity/mortality rates are failing to decline as a result of excessive c-sections. Excessive c-sections are also associated with poor maternal and perinatal outcomes. A Brazilian study of three birth cohorts (1982, 1993, and 2004) from the city of Pelotas, Southern Brazil, showed that c-section rates increased in both public (from 23.6% to 34.1%) and private (49.4% to 82.4%) sectors, with a much higher proportion in the latter. Maternal characteristics have improved: women have become taller, better nourished and educated, smoke less, begin antenatal care earlier, and have more antenatal care appointments. However, the percentage of preterm deliveries increased (from 6.3% in 1982 to 16.2% in 2004) both among c-sections and vaginal births, leading to a mean reduction of 47 g in newborn weight. The increase in preterm vaginal births was associated with a 2.5% increase in inductions, which reached 43.0% in 2004, although these data may not be entirely reliable, given that they were self-reported by the mothers.⁵

Elective c-sections may result in iatrogenic preterm birth, prolong hospitalization, and have a negative effect on breastfeeding.^b C-sections involve surgical and anesthesia-related risks, and may have long-term consequences on later pregnancies, including conditions of high hemorrhagic risk (such as placenta previa and placenta accreta), which may often lead to maternal death.^ª As an attempt to reduce these issues, efforts have been made to avoid primary or repeat c-sections. In the Unites States, the vaginal delivery rate among women with one prior c-section and who did a trial of labor remains around 74%.^c

Strategies aimed at reducing c-section rates in Brazil, include the creation of Birth Centers (BC). Created in 1998 through Ministry of Health statute GM 985/99,^d BCs are aimed at promoting vaginal birth outside the surgical environment. These facilities value the physiology of vaginal delivery, the presence of the partner, and the immediate contact between mother and newborn. Vaginal delivery care is provided by nurse-midwives and midwives, and may take place in in-hospital, alongside or freestanding birth centers. Encouragement of vaginal delivery and delimitation of the interventions provided by physicians and nurses are among the foundations of the BC philosophy.² Nurse-midwives and midwives are legally entitled to provide care during physiological delivery in Brazil.^e In the BC, physicians are usually only required for surgical delivery or in the case of complications.

Although there are a small number of studies^7,14,16 investigating the results obtained by BCs in Brazil, few of these address the use of c-sections within these centers. Thus, the aim of the present study was to estimate the prevalence of c-sections in a BC, and to identify its associated factors.

METHODS

We carried out a cross-sectional study in an intra-hospital BC in the city of Sao Paulo, Southeastern Brazil. This BC provides care to pregnant women classified as of low-risk. Care for labor and vaginal delivery is provided by nurse-midwives and midwives. Any abnormalities in the physiological labor process or in fetal vitality are referred to obstetricians. Examples of such alterations include meconium-stained amniotic fluid, failure to progress, and deceleration of fetal heart rate, among others.

Our study population comprised all births taken place within the institution between March and April 2005, totaling 2,441 mothers and their newborns. The survey was conducted by manual review of pregnancy charts, from which data on mother, labor, delivery, and newborn were extracted and transcribed to our own forms. Missing data from pregnancy charts were defined as "losses." Variables in the study included maternal age, parity, gestational age, obstetric history, use of oxytocin, duration of labor, c-section indication (categorized as fetus-related, labor-related, and other), and birthweight.

The dependent variable (mode of delivery) was classified as vaginal or c-section, and independent variables were grouped into maternal age and current/prior obstetric history; delivery care; and perinatal outcomes.

In order to measure the association between c-section and the other variables, we calculated prevalence ratios (PR) and their respective 95% confidence intervals (95%CI). In cross-sectional studies, measures of association are presented as odds ratios (OR) and PRs. In the literature, there is an intense discussion among epidemiologists as to which measure (OR or PR) is most appropriate to measure the effects of risk factors. When prevalence of the class of interest is high (greater than 10%, for instance), the OR overestimates the PR. Confusion arises when prevalence is interpreted as a PR. This approximation may be considered correct when prevalence of the studied class is low (as in the case of rare diseases).⁴ In the present study, we use the delta method¹⁹ to estimate confidence intervals for PRs.

The present study was approved by the Research Ethics Committee of the School of Nursing of the University of Sao Paulo (Process no. 527/2006).

RESULTS

Of a total of 2,441 births taken place during the study period, 336 were by c-section, corresponding to 14.9% of all deliveries. Adolescent mothers accounted for approximately 11% of the sample. C-sections were most prevalent among older women. History of prior c-sections and gestational age over 40 weeks were also associated with higher prevalence of c-sections (Table 1).

Oxytocin was administered to 41.4% of women. There was no significant association between use of oxytocin and prevalence of c-sections (Table 2).

Time of the day was associated with mode of delivery. Deliveries that took place between 7 p.m. and 11:59 p.m. were less likely to have been by c-section than those that took place during the day shift. Those taking place during early hours (midnight to 6:59 a.m.) were even less likely to be by c-section. Regarding the length of time between admission and delivery, intervals from 7 to 12 hours emerged as a protective factor against c-sections when compared to shorter periods. Almost one-quarter of women that delivered via c-section underwent surgery less than one hour after admission; most of these women had had repeated (two or more previous) c-sections.

Women admitted to the BC with no cervical dilation were more likely to undergo c-section when compared to women with 5-9 cm. Women with meconium-stained the amniotic fluid were also more likely to undergo c-sections compared to those with clear fluid. Birthweight was also associated with mode of delivery: babies born weighing under 2,500 g and over 3,500 g were more likely to have been delivered by c-section.

Women who delivered vaginally in their previous pregnancies showed lower prevalence of c-sections, even when their obstetric history included a prior c-section (PR 0.46, 95%CI 0.30;0.71, p = 0.0010). Taking obstetric history into account, 283 women had a history of c-sections in their previously delivery. Of these, 175 (61.8%) delivered their current babies vaginally, while 108 (38.2%) did so by c-section.

In 206/366 women (56.3%), c-sections were primary, that is, were for the woman's first delivery. Fetal distress emerged as the major indication for this procedure, followed by failure to progress through labor.

Among the indications for c-sections, we found that factors associated to the newborn, such as fetal distress, meconium-stained amniotic fluid (diagnosed by cardiotocography), macrosomia, and breech presentation accounted for 47.8% (175) of c-section indications. Labor-related conditions, such as failure to progress, functional dystocia, and shoulder dystocia accounted for 31.3% (115) of these indications (Table 3).

DISCUSSION

In the present study, the rate of c-sections (14.9%) was within the 15% limit proposed by the World Health Organization (WHO) in 1985.²⁵ A number of authors have questioned this ideal rate, arguing that it is inconsistent and that ideal rates should reflect resource availability and women's preferences.^ª Notwithstanding, the rate found in the present study was lower than those observed in public hospitals (29.7%) and medium complexity hospitals (28.1%).²⁰

Women aged 35 of older were 20% more likely to deliver by c-section than those aged 20-34 years (although this difference was not statistically significant). Women under 20 years of age were 33% less likely to undergo a c-section. Studies of the factors associated with c-sections in Brazilian hospitals found that women aged 35 years or older have twice the prevalence of c-sections than women aged under 20 years.²⁰

Roughly 60% of women whose previous delivery had been by c-section delivered their current babies vaginally, and we observed no cases of uterine rupture. These results are in agreement with those of surveys that compare planned c-sections and planned vaginal birth among women with a history of c-sections.^11,12 Success rates for vaginal birth after c-section ranged from 64% to 85%, whereas prevalence of uterine rupture ranged from 0.16% to 2.1%.¹¹ In the review that compared planned induction with c-section for women with one prior c-section, prostaglandins and oxytocin were reported as being used for labor induction, in spite of such use being contraindicated for women with uterine scars by the drug manufacturers.¹² Neither review was able to find randomized studies on the subject. Their results must therefore be interpreted with caution, given that risks and benefits may be overestimated by bias in the surveys reviewed.

A report by the United States National Institutes of Health concluded that rates of vaginal birth after c-section have decreased significantly since 1996,^c in association with a number of obstetric and demographic factors. According to this study, African or Hispanic ascendance, being single, having less than 12 years of schooling, having a maternal disease, and being admitted at a rural or private hospital are among the factors associated with lower probability of delivering vaginally after a c-section.

In this sense, having had a prior c-section may, in conjunction with other factors, influence the decision to deliver vaginally in the current pregnancy. A study carried out in Greece analyzed c-section indications between 2002 and 2009. The predominant reason for indicating a c-section in this study was previous c-section (30.9%), followed by cardiotocographic abnormalities (12.3%).¹⁰ This was the only reason for indication that increased significantly during the studied period. Choudhury & Dawson⁸ showed a similar trend in a study of a 7-year period in Wales. In this study, prior c-sections accounted for 20% of surgical delivery indications. In the present study, prior c-section was not a determinant factor for current c-section. However, based in our clinical experience, prior c-sections, when associated with other maternal characteristics, such as age greater than 35 years, suspected macrosomia or rupture of membranes, and unfavorable cervix may increase the probability of a c-section indication. We also found that prolonged pregnancies tend to be more strongly associated with induction of labor, use of oxytocin, presence of meconium, and c-section delivery.

Considering the possibility of vaginal delivery for women with prior c-sections may be a means to reduce the high rates of surgical delivery in Brazil.

It is difficult to analyze c-section indications in cases where this procedure is performed almost routinely. Thus, we sought studies from countries in which c-section indications are thought to be related more closely to medical than to economic reasons.

In Pakistan, a study comparing the clinical and epidemiological characteristics of women undergoing c-sections, either for the first time or after prior c-sections, found an overall rate of 13.6%, of which 70.1% were primary and 29.9%, were repeat c-sections. Characteristics associated with primary c-sections were age under 20 years, early rupture of membranes, labor induction, and birthweight > 3.500 g. Emergency procedures were predominant among primary c-sections.²¹ In the present survey, mother's age was not associated with c-section indication; however, birthweight > 4 kg and presence of meconium were associated with this outcome.

In a study carried out in Singapore, the rate of c-sections increased from 16.8% in 1998 to 25.1% in 2001. Rates of primary and placenta previa-related c-sections showed the greatest increase.²³ A similar phenomenon is taking place in Greece. Primary c-sections, which, between 1977 and 1983 accounted for 6.1% of these surgeries, increased to 19% in the period from 1994 to 2000.²² Despite this increase, these rates were still lower than those found in the present study. In Saudi-Arabia, the c-section rate in a medical facility was 18%. C-sections were mostly due to dystocia (more frequent among young women and primiparas) and to repeat c-sections (among multiparas). Fetal monitoring was implicated as a cause of inadequate c-section indication.⁹ In the present study, the proportion of c-section indications due to dystocia was 15.2%. In another Brazilian survey, the c-section rate in a university hospital was 10.3%, with 6.1% of primary c-sections. Major reasons for c-section were breech presentation, failure to progress, and fetal distress.¹⁵

A multicenter study¹³ involving four countries in Southeast Asia (Indonesia, Malaysia, Phillipines, and Thailand) analyzed the hospital delivery records of nine participating institutions. This study included 9,550 women and 9,665 newborns; c-section rates ranged from 19% to 35% between countries, and from 12% to 39% among hospitals within a same country. The major reason for c-section indication was prior c-section (7%); followed by cephalopelvic disproportion (6.3%) - more than twice the proportion found in the present study (2.7%); breech presentation (4.7%); and fetal distress (3.3%) - much lower than in the present study (23.2%). In the present study, history of prior c-section increased the probability of c-section in the current delivery by more than three fold.

C-sections are becoming more frequent in cases of breech presentation. Nonetheless, there are professionals who argue for its resolution by vaginal delivery. In the present study, all cases of breech presentation were resolved by c-section, accounting for 8.2% of the indications for this procedure. In a Saudi hospital, of 112 deliveries by first-time mothers with breech presentation, 96 (857%) entered labor, and 67 (69.8%) delivered vaginally. Perinatal results did not differ between the two groups.¹ In Athens, Greece, the proportion of c-sections related to breech presentation increased from 16.9% in 1965 to 74.1% in 1995. In the same period, neonatal mortality decreased from 70.1% to 36.6%. Thus, a four-fold increase in c-sections reduced by half the perinatal mortality among fetuses with breech presentation.¹⁷ On the other hand, a study carried out in a hospital in England investigated c-section indications in a 7-year period, showing that the percentage of c-sections due to breech presentation remained constant throughout the surveyed period, ranging from 10.4% in 2002 to 11.4% in 2007.⁸

The increase in the proportion of c-sections in WHO's Global Survey on Maternal and Perinatal Health was associated with a worsening of perinatal outcomes, including increases in preterm deliveries and admission to neonatal intensive care units.²⁴ The authors of this survey concluded that increased c-section rates were associated with greater use of antibiotics in the postpartum period and greater maternal and newborn morbidity and mortality, even after adjustment for demographic characteristics, risk factors, clinical complications of pregnancy, type and complexity of the institutions where babies were delivered, and percentage of transfers. There was increased risk of perinatal mortality at c-section rates between 10% and 20%. In hospitals with high c-section rates, the greater proportion of babies that remain in intensive care for seven days or more may be related to the respiratory distress syndrome associated with elective c-section.²⁴

A limitation of the present study is that data are collected from secondary sources (patient charts) spanning a relatively short period, and which may have been influenced by other variables, such as absence of a protocol for c-section indication.

However, our results may provide input for improving c-section indication criteria. Careful monitoring of fetal conditions during labor, especially in pregnancies lasting longer than 40 weeks, may decrease the rate of c-sections.

Prevalence of c-sections in this in-hospital Birth Center was lower than the rates found in other maternity wards across the country, in both the public and private networks.

REFERENCES

Received: 7/1/2010

Approved: 5/17/2011

The authors declare no conflict of interest.

Rev Saude Publica.

2011;45(6):1037

Results (abstract)

Onde se lê | Where it reads

"Factors related to fetal conditions including fetal stress, meconium-stained amniotic fluid, breech presentation and macrosomia accounted for 47.8% (175) while those related to the mechanism of birth including arrest disorders, and functional rotation dystocia accounted for 31,3% (115) of all indications for a cesarian section."

Leia-se | It should read

"Factors related to fetal conditions including fetal stress, meconium-stained amniotic fluid, breech presentation and macrosomia accounted for 47.8% (175) while those related to the mechanism of birth including arrest disorders, functional dystocia and malposition accounted for 31,3% (115) of all indications for a cesarian section."

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a

Agênci Ncionl de Súde Suplementr. O modelo de tenção obstétric no setor de súde suplementr no Brsil: cenários e perspectivs. Brsíli (DF): Ministério d Súde; 2008 [cited 2010 Jun 23]. Avilble from:

http://bvsms.saude.gov.br/bvs/publicacoes/modelo_atencao_obstetrica.pdf

b

NIH State-of-the-Science Conference Statement on Caesarean Delivery on Maternal Request. NIH Consens Sci Statements. 2006. Mar 27-29; 23(1) 1-29. [cited 2010 Jun 22]. Available from:

http://consensus.nih.gov/2006/cesareanstatement.pdf

c

NIH Consensus Development Conferene Statement Vaginal Birth After Caesarean: new insights. NIH Consens Si Statements. 2010. Mar 8-10;27(3):1-48. [ited 2010 Jun 22]. Available from:

http://consensus.nih.gov/2010/images/vbac/vbac_statement.pdf

d

Ministério da Saúde. Portaria no 985/GM, de 5 de agosto de 1999. Cria o Centro de Parto Normal-CPN, no âmbito do Sistema Único de Saúde. Brasília (DF); 1999. [cited 2010 Jun 22]. Available from:

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e

Ministério da Saúde. Portaria nº 163, de 22 de setembro de 1998. Reafirma as atribuições da enfermeira obstetra e da obstetriz e aprova modelo do laudo de Enfermagem para emissão da A.I.H.

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http://sna.saude.gov.br/legisla/legisla/obst/SAS_P163_98obst.doc

Publication Dates

• Publication in this collection
  10 Aug 2012
• Date of issue
  Dec 2011

History

• Accepted
  17 May 2011
• Received
  01 July 2010