Prenatal risk factors for Caesarean section. Analyses of the ALSPAC cohort of 12,944 women in England

BACKGROUND: There has been an escalation in Caesarean section rates globally. Numerous prenatal factors have been associated with elective and emergency Caesarean section, some of which may be amenable to change. METHODS: A population-based cohort of 12,944 singleton, liveborn, term pregnancies were used to investigate risk factors for Caesarean section using multivariable logistic regression modelling. Numerous prenatal factors were investigated for their associations with the following outcomes: first, with Caesarean section (both elective and emergency) compared with vaginal delivery (spontaneous and assisted); second, for their associations with elective Caesarean section compared with attempted vaginal delivery; and finally emergency Caesarean section compared with spontaneous vaginal delivery. RESULTS: 11,791 women had vaginal delivery and 1153 had Caesarean section (685 emergency, 468 elective). Non-cephalic (breech) presentation (all Caesareans odds ratio (OR) 36.6, 95% confidence interval (CI) 26.8-50.0; elective Caesarean OR 86.4, 95% CI 58.5-127.8; emergency Caesarean OR 9.58, 95% CI 6.06-15.1) and previous Caesarean section (all Caesareans OR 27.8, 95% CI 20.9-37.0, elective Caesarean OR 54.4, 95% CI 38.4-77.5; emergency Caesarean OR 13.0, 95% CI 7.76-21.7) were associated in all analyses with an increased risk of Caesarean section. Extremes of neonatal birthweight were associated with an increased risk of Caesarean section (all Caesareans and emergency section) compared with vaginal delivery as was increasing neonatal head circumferences. In all analyses increasing maternal age (OR 1.07 per year, 95 % CI 1.04-1.09; OR 1.04 per year, 95 % CI 1.01-1.08; OR 1.11 per year, 95% CI 1.08-1.15) was independently associated with increased odds of Caesarean section. Increasing parity was associated with a decrease in risk for all Caesareans and emergency section (OR 0.63, 95% CI 0.53-0.75 and OR 0.46, 95% CI 0.33-0.63, respectively), as was the outcome of the last pregnancy being a live child. Increasing gestation was independently associated with a decreased risk of both all Caesareans and elective Caesarean (OR 0.86, 95% CI 0.80-0.93 and OR 0.52, 95% CI 0.46-0.58 respectively), whereas diabetes mellitus was associated with increased risk. These variables were not associated with emergency section. However, epidural use was associated with an increased risk of emergency Caesarean (OR 6.49, 95% CI 4.78-8.82) while being in a preferred labour position decreased the risk (OR 0.59, 95% CI 0.49-0.73). CONCLUSIONS: A careful exploration of risk factors may allow us to identify reasons for the increasing rates of Caesarean section and the marked variation between institutions.     

An investigation of Caesarean sections in three Greek hospitals: the impact of financial incentives and convenience

BACKGROUND: Caesarean section (CS) rates have been increasing dramatically in the past decades around the world. The objective of our study was to investigate the factors increasing the likelihood of undergoing CS in two public hospitals and one private hospital in Athens, Greece. Specifically, the purpose was primarily to assess the impact of non-medical factors such as private health insurance, potential for making informal payments, physician convenience and socio-economic status on the rate of CS deliveries. METHODS: All available demographic, socio-economic and medical information from the medical records of all deliveries in the three hospitals in January 2002 were analysed. The relative importance of the variables in predicting delivery with CS rather than normal vaginal delivery was calculated in multiple logistic regression models to generate odds ratios (OR). RESULTS: The CS rate in the public hospitals was 41.6% (52.5% for Greeks and 26% for immigrants), while the CS rate in the private hospital was 53% (65.2% for women with private insurance and 23.9% for women who paid directly). In the public hospitals, after controlling for demographic and medical factors, Greek ethnic background, delivery between 8 a.m. and 4 p.m., between 4 p.m. and midnight, and on Monday, Wednesday and Friday were found to increase the likelihood of CS delivery. In the private hospital, having private health insurance is the strongest predictor of CS delivery, followed by delivery between 8 a.m. and 4 p.m., between 4 p.m. and midnight, delivery on a Saturday and being a housewife. CONCLUSION: The results of this study lend support to the hypothesis that physicians are motivated to perform CS for financial and convenience incentives. The recent commercialization of gynaecology services in Greece is discussed, along with its implications on physicians' decisions to perform CS.     

Can Caesarean section improve child and maternal health? The case of breech babies

This paper examines the health effects of Caesarean section (CS) for children and their mothers. We use exogenous variation in the probability of CS in a fuzzy regression discontinuity design. Using administrative Danish data, we exploit an information shock for obstetricians that sharply altered CS rates for breech babies. We find that CS decreases the child's probability of having a low APGAR score and the number of family doctor visits in the first year of life. We find no significant effects for severe neonatal morbidity or hospitalizations. While mothers are hospitalized longer after birth, we find no effects of CS for maternal post-birth complications or infections. Although the change in mode of delivery for the marginal breech babies increases direct costs, the health benefits show that CS is the safest option for these children.     

Cesarean section rates in Italy by hospital payment mode: an analysis based on birth certificates.

The study, based on birth certificate data from 1985 through 1987, investigated cesarean section (CS) rates in the Lazio region of Italy and their relationship with mode of hospital care payment. Use of abdominal delivery increased from 22.3% in 1985 to 24.3% in 1987. CS rates were highest (34.7%) in private hospitals. A marked variation in the use of CS was associated with mode of hospital care payment independently from other predictors of abdominal delivery.     

Risk factors for low birthweight in north-east Brazil: the role of caesarean section

Caesarean section (CS) delivery is associated with low birthweight (LBW) in south‐east Brazil. A hospital‐based study was conducted on singleton infants from mothers residing in São Luís, to assess if an association between CS and LBW was found in the northern part of the country, where the CS rate is lower than in the south‐east. A standardised questionnaire was administered to a sample of 2541 mothers in 10 hospitals, representing 94% of all deliveries, from March 1997 to February 1998. In a logistic model, type of delivery was the independent variable, the other variables were treated as confounders, and interaction terms were added between type of delivery and all other factors. LBW was associated with low maternal height, maternal smoking, primiparity, previous LBW, public insurance, preterm birth and CS. The CS rate was 33.7%. The risk of CS was higher for primiparous and married mothers, those with high level of schooling and attended by the same physician during prenatal and delivery care, deliveries held in private hospitals, daylight hours or evenings, and for those mothers who had adequate prenatal care. Because it appears unlikely that only medical reasons are operative, it is a possibility that CS could cause LBW, reflecting abusive indications for elective CS.     

The relationship between Caesarean section and neonatal mortality in very-low-birthweight infants born in Washington State, USA

We examined the associations between Caesarean section and neonatal mortality in singleton liveborn very-low-birthweight (VLBW) infants (500-1499 g) born during 1984-95 in Washington State, USA, using data from the Washington State birth certificate files. The infants included in this study had no life-threatening congenital malformations and had not been delivered by a repeat Caesarean without a trial of labour (n = 5182). For infants weighing 500-749, 750-999, 1000-1249 and 1250-1499 g, the neonatal mortality rates were 57.8%, 18.6%, 9.7% and 4.7%, respectively, and the Caesarean section rates were 28.4%, 47.8%, 48.0% and 44.6%. The adjusted odds ratios (ORs) for neonatal death associated with Caesarean section were 0.55 [95% confidence interval 0.38, 0.78] for the 500-749 g infants (n = 1059), and 1.15 [0.91, 1.45] for the larger (750-1499 g) infants, after adjustment for birth year, type of hospital, birthweight, presence or absence of labour, breech/malpresentation, and other obstetric indications for Caesarean section (prolapsed cord, placenta praevia, eclampsia, pre-eclampsia and chronic hypertension). However, when the larger (750-1499 g) vertex-presenting (n = 3248) and breech/malpresenting (n = 809) infants were considered separately, the adjusted ORs were 1.42 [1.05, 1.91] and 0.37 [0.23, 0.58] respectively. In contrast, among infants weighing 500-749 g, the ORs were not modified by presentation. The results were similar when we restricted analyses to infants without the above obstetric indications for Caesarean section. Because such an observational study is liable to unmeasurable biases and incomplete reporting of obstetric complications, these OR estimates may be subject to residual confounding. In their present state, these recent population-based data support the view that Caesarean sections do not enhance the neonatal survival of larger (> 750 g) VLBW babies when obstetric complications are absent. The possibility of a protective effect of Caesarean section on the survival of breech/malpresenting infants and infants weighing 500-749 g deserves further studies.     

A history of placental dysfunction and risk of placental abruption

In a population-based historic cohort study, we assessed the possible association of fetal growth retardation, preterm birth and pregnancy-induced hypertension in the immediately preceding pregnancy with placental abruption in the current pregnancy, which would suggest a shared aetiological factor. We also assessed whether chronic hypertension, diabetes mellitus and a history of Caesarean section are associated with placental abruption. Preterm birth and small-for-gestational-age (SGA) in the immediately preceding delivery were associated with an increased risk of placental abruption with unadjusted odds ratios (ORs) of 2.1 [95% CI = 1.9, 2.4] and 1.6 [95% CI = 1.5, 1.8] respectively. Women with a history of an SGA preterm birth in the immediately preceding delivery and an appropriate-for-gestational-age infant in the current had an adjusted OR of 3.2 [95% CI = 2.3, 4.5]. The adjusted odds ratio of placental abruption in women who had pregnancy-induced hypertension in the previous pregnancy, but not in the current, was 1.4 [95% CI = 1.2, 1.7]. Women who delivered a preterm or SGA infant in the previous delivery and had chronic hypertension or diabetes mellitus in the current had adjusted ORs of 2.3–5.7 and 2.5–6.0 respectively. Caesarean section in the previous delivery increased the risk of placental abruption by 40%. These results suggest that pregnancy-induced hypertension, intrauterine growth retardation, preterm delivery and placental abruption share an aetiological factor or represent different clinical expressions of recurring placental dysfunction. Chronic hypertension and diabetes mellitus may cause or aggravate such dysfunction thus causing placental abruption. A history of Caesarean section is associated with an increased risk of placental abruption.     

The effect of physicians’ remuneration system on the Caesarean section rate: the Uruguayan case

Using data about births from the perinatal information system (PIS) registered in Montevideo (Uruguay), we estimated the probability of having a Caesarian section delivery, controlled by risk factors and the endogeneity of the choice of hospital. In public hospitals in Montevideo there is a fixed payment system, but in private hospitals this procedure has to be paid for separately. In the former, there is no effect on the doctor’s income if he performs a Caesarian, but in the latter there is a positive effect. Empirical evidence shows the probability of a Caesarean section increases with the age of the woman, the presence of eclampsy, pre-eclampsy, previous hypertension, previous Caesarean sections, multiple pregnancies and fetopelvic disproportion, and decreases for multiparous women and women in a public hospital. In fact, the probability of having a Caesarean section in a private institution is almost two times higher than in a public hospital (20% as against 39%). Focusing on women without risk factors, we found that the probability a Caesarian in a public hospital was 11%, but the probability in a private hospital was 25%. We conclude that the remuneration system explains an important part of this difference.     

Determinants of caesarean section in Lebanon: geographical differences

This study, based on the Lebanese National Perinatal Survey which included 5231 women, examined the relations between the caesarean section (CS) rate and the characteristics of mothers, children, antenatal care and maternity units in two geographical zones of Lebanon (Beirut-Mount Lebanon and the rest of the country) and then looked at geographical variations. This analysis concerned 3846 women with singleton pregnancies and livebirths at low risk of CS, after exclusion of women with a previous CS, non-cephalic fetal presentations, or delivery before 37 weeks' gestation. The principal end point was caesarean delivery. The relations between the factors studied and CS were estimated by odds ratios (OR), both crude and adjusted, using logistic regression. The rate of CS was higher in the Beirut-Mount Lebanon zone than elsewhere (13.4% vs. 7.6%). After adjustment, several factors remained associated with caesarean delivery in each zone. Common factors were primiparity, gestational age > or = 41 weeks and antenatal hospitalisation. Factors identified only in the Beirut-Mount Lebanon zone were obstetric history and insurance coverage, whereas for the other zones we only found major risk factors for obstetric disease: maternal age > or = 35 years, number of antenatal consultations > or = 4 and birthweight < or = 2500 g. The multivariable analysis of the overall population, adjusting for zone of delivery and other variables, shows that zone was one of the principal factors associated with the risk of caesarean delivery in Lebanon (OR = 1.80 [95% CI 1.09, 2.95]). In conclusion, the CS rates in Lebanon were high, with geographical differences that were associated with access to care and with obstetric practices.     

Attempt and success rates for vaginal birth after Caesarean section in relation to complications of the previous pregnancy

The relationships between prior obstetrical complications and subsequent trial of labour and vaginal birth after Caesarean (VBAC) success likelihood were examined among a cohort of Washington State women with a first livebirth via Caesarean delivery and a second livebirth between 1987 and 1993 ( n  equals; 10 110). Overall, 64% of the cohort undertook a labour trial, and 62% of those who attempted VBAC delivery were successful, for an overall VBAC rate of 40%. Women with fetal macrosomia, cephalopelvic disproportion, prolonged labour, diabetes, or placental problems in the first pregnancy were less likely to undergo a labour trial in the second pregnancy than those without these factors, while women with prior induced labour, genital herpes, fetal distress, or breech presentation were more likely to attempt vaginal birth. Approximately half of women with prior macrosomia, labour problems, or chronic medical conditions who attempted VBAC succeeded, as did three-quarters of women with prior breech presentation or placental conditions. Overall VBAC rates were around 33% for women with previous fetal macrosomia, labour problems, or chronic medical conditions, and 45–55% among those with herpes, fetal distress or breech presentation at the first birth. Trial of labour should especially be encouraged among women without prior labour problems.     

Increase of births by cesarean section in Campania in 2000

Cesarean deliveries (CS) are increasing in Italy, especially in the Campania region, where they reached a peak incidence of 52% in the year 2000. This study analyses CS rate variability by hospital type, foetal risk factors (low birth-weight, prematurity, plurality, anomalous presentations), maternal characteristics (age and parity) and delivery time. Data are drawn from birth certificates of 31,182 babies, that is 64.2% of all delivered in 65 out of 98 Campania birth-places. 16,251 (52%) babies are born by CS; 559 (1.8%) by operative vaginal delivery. The Attributable Risk for foetal risk factors is 6.9%. In absence of these the CS rate would be 48.5% instead of 52%. CS rate of primigravid women was 53.2%. 63% of CS take place during morning hours and 93% on working days. CS rate is higher in private than in public hospitals (58 vs 46%), though foetal risk factors are lower. Rate of older women was higher in public hospitals, rate of primigravid women was higher in private ones. Campania data confirm the marginal role of foetal risk factors in the increase of CS rate. In order to reduce CS rates it seems reasonable to offer special support to primigravid low risk mothers and to provide behavioural obstetrical guidelines for the peculiar Italian reality.     

Factors associated with vaginal birth after previous cesarean section in Brazilian women.

OBJECTIVE: To identify factors associated with a vaginal second delivery in women who had one previous cesarean section. METHODS: A nested case-control study was carried out as a secondary data analysis of an original retrospective, population-based cohort study of women who delivered their first child during 1985 in the city of Campinas, S?o Paulo, Brazil, and who were interviewed 10 years later in 1995. The study population consisted of 1352 women who had their first delivery by cesarean section and who had also had at least one subsequent delivery. The group of cases (150 women, around 11% of the sample) consisted of women who had a vaginal second delivery, and the control group was made up of 1202 women who had a cesarean section at second delivery. For each possible associated factor we calculated the odds ratio and 95% confidence interval. For ordered categorical variables the c2 test for trend was used. Unconditional multivariate regression analysis was used to estimate the adjusted odds ratio for each associated factor. RESULTS: The factors significantly associated with vaginal delivery were monthly family income below 5-fold the Brazilian minimum monthly wage, reliance on the Brazilian national health system for healthcare, low maternal age, and first cesarean section indicated because of fetal breech or transverse presentation, or twin pregnancy. Among those women who also had a cesarean section at their second delivery, only 11% had undergone a trial of labor. CONCLUSIONS: The main determining factors for a vaginal second delivery in women with a previous cesarean section were unfavorable social and economic factors.     

Factors associated with preterm births in southeast Brazil: a comparison of two birth cohorts born 15 years apart

An increase in preterm deliveries in Ribeirão Preto stimulated an analysis of possible explanatory factors. Two cohorts of singleton livebirths were studied, the first based on 6746 births in 1978–9 and the second based on 2846 births in 1994. A logistic regression was carried out to assess the association of preterm birth with several socio‐demographic, behavioural and clinical variables, including year of survey. Delivery in private settings compared with a public setting, maternal age of 17 compared with any other age group, and mothers who had had previous abortions and previous stillbirths were associated with greater rates of preterm birth. Although there was an increase in preterm birth rates regardless of mode of delivery, the increase was greater in the caesarean section group than in the vaginal delivery group. Over the study period, deliveries in private hospitals and caesarean section operations increased markedly (from 4% to 36% and from 30% to 51% respectively). Caesarean section may be the main contributor to the increase of preterm birth rate in this study. It is essential to ensure that health‐care staff, especially those in private facilities, are properly educated and audited.     

Breech presentation at term: elective caesarean section is the wrong choice as a standard treatment because of too high risks for the mother and her future children

The altered attitude of the obstetrician with regard to term breech delivery after the first results of the Term breech trial in 2000 has led to an increase in elective caesarean section in the Netherlands from 25% in 1999 to 64% in 2004 and a decrease in emergency caesarean section for term breech delivery from 26% in 1999 to I8% in 2004. This increase of about 8500 elective caesarean sections in the last four years probably prevented 19 perinatal deaths. However, this rise in caesarean section also resulted in four maternal deaths that may have been avoidable. Furthermore, in the future, nine perinatal deaths as a result of the uterine scar and 140 women with potentially life-threatening complications from that uterine scar during their future pregnancies can be expected. Information to the patient should take into account not only the short-term benefits but also the higher long-term risks. Vaginal delivery following strict selection is now preferred.     

非洲桑给巴尔奔巴地区剖宫产指征及原因分析

目的探讨和分析非洲桑给巴尔奔巴岛地区剖宫产的指征及原因,以提高产科质量。方法选择2008～2011年奔巴岛AbdullaMzee医院行剖宫产的564例病例,用回顾性分析的方法进行统计。结果奔巴岛Abdulla Mzee医院的剖宫产率为10.01%。剖宫产的主要原因为头盆不称(27.13%)、瘢痕子宫(23.40%)、重度子痫前期及子痫(13.30%)、胎儿因素(9.75%)、胎儿宫内窘迫(9.40%)、妊娠合并症(6.91%)等。结论剖宫产在处理难产及某些孕期合并症、并发症,降低孕产妇和围产儿死亡率方面发挥了极大的作用,但是在非洲这种医疗条件比较落后的地区,剖宫产仍存在着很大的风险,不必要的剖宫产术并不能减少产后出血率及新生儿发病率。当地医护人员应提高助产技术水平,建立并完善正规的产前检查系统,以提高产科质量。     

2565例住院分娩产妇剖宫产率及剖宫产指征分析

目的分析高剖宫产率的原因，为降低剖宫产率的对策提供依据。方法对2010—2013年在江苏省金坛市中医医院分娩的2565例产妇的临床资料进行回顾性分析，统计分析不同时期剖宫产率及其指征比率的变化。结果2010—2013年我院剖宫产率分别为57．43％、55．94％、56．71％、55．51％，平均剖宫产率为56．18％。剖宫产指征前五位分别为：社会因素、疤痕子宫、巨大儿、胎儿宫内窘迫、胎位异常。结论高剖宫产率是由多种因素造成的，加强围产保健宣传力度，更新产科医生服务理念等可有效降低剖宫产率。     

Risk factors for the increasing caesarean section rate in Southeast Brazil: a comparison of two birth cohorts, 1978-1979 and 1994.

BACKGROUND: Brazil has the highest caesarean section (CS) rate in the world (36.4% in 1996). METHODS: Risk factors for increasing CS rate were studied in two population-based cohorts of singleton live births in families residing in the municipality of Ribeirao Preto, State of Sa? Paulo, Southeast Brazil. The first comprised births from June 1978 to May 1979 (6750 births-one-year survey) and the second births from May to August 1994 (2846 births-4-month survey). Multiple unconditional logistic regression modelling was used to control for confounding. RESULTS: The CS rate rose from 30.3% in 1978-1979 to 50.8% in 1994. In 1978-1979, socioeconomic, reproductive and demographic variables, and health service factors were associated with CS rate. In 1994, only reproductive, demographic and health service factors remained associated, e.g. hour of delivery (from 7 a.m. to 12 p.m.), attendance by the same physician for prenatal care and delivery, > or =4 prenatal visits, maternal age > or =30 years, 1-3 previous live births and birthweight 3500-3999 g. CONCLUSION: Caesarean section in Brazil is widely performed for non-medical reasons in which physician convenience plays an important role. There is an urgent need for public health interventions to reduce the CS rate in Brazil, mainly directed towards cultural beliefs and physician behaviour.     

The effect of perinatal screening in Norway on the magnitude of noninherited risk factors for congenital dislocation of the hip

Several investigators have noted an increase in the rate of congenital dislocation of the hip shortly after the initiation of neonatal screening procedures. This increase has been attributed to the detection of temporarily unstable hips which require no corrective treatment. To test whether neonatal screening had low specificity, the authors obtained data on 17,145 offspring of 7,896 twins from the Norwegian Twin Panel. Information from maternal reproduction history questionnaires was available on the presence or absence of congenital dislocation of the hip, type of obstetric delivery, and parity. The reported prevalence of the disorder did indeed begin to rise sharply during the late 1950s, at which time neonatal screening started in Norway. Infants were then grouped by year of birth (born before or after 1960), and odds ratios were calculated for breech delivery and early (first or second) parity. For the pre-screening group, the odds ratio of congenital dislocation of the hip was 7.7 among children delivered by breech presentation and 2.6 among those of early parity. These values are similar to those found in other studies. In the post-screening group, the odds ratios for breech delivery and early parity were 1.5 and 1.2, respectively. Breech delivery and early parity have been consistent risk factors for congenital dislocation of the hip. Their diminished influence in the post-screening group, as well as sharply increased rates of the disorder, suggests that in Norway neonatal screening programs may have had low specificity in detecting cases that required treatment.     

Social inequalities in cesarean section rates in primiparae, Southern Brazil

OBJECTIVE: To investigate the effect of social inequalities in cesarean section rates among primiparae having single pregnancy and delivering in maternity hospitals. METHODS: The study was carried out in Southern Brazil in 1996, 1998 and 2000. Data from the Live Birth National Information System were used to estimate annual rates and crude and adjusted odds ratios (OR) of cesarean sections according to social conditions (maternal age and education, newborn skin color/ethnicity and macro-regions), duration of pregnancy, and number of prenatal visits. RESULTS: The overall cesarean section rate was 45%, and above 37% in all macro-regions. Increased rates were seen among native and black mothers, aged 30 years or more, living in metropolitan, river valley and mountain macro-regions and having attended to more than six prenatal visits. Crude and adjusted OR show that cesarean rates were negatively associated with all categories of skin color/ethnicity when compared to white newborns, particularly those of native Brazilian (ORadj=0.43; 95% CI: 0.31-0.59), and they were positively associated with higher maternal education (ORadj=3.52; 95% CI: 3.11-3.99), older age (ORadj=6.87; 95% CI: 5.90-8.00) and greater number of prenatal visits (ORadj=2.16; 95% CI: 1.99-2.35). The effects of age and education were partly mediated by the greater number of prenatal visits among higher educated older women. The OR varied among macro-regions but were greater for the wealthier mountain region. CONCLUSIONS: High rates of cesarean section rates in Southern Brazil are a public health concern. They are associated with social, economic and cultural factors which can lead to misuse of medical technology during labor and delivery.