OBJECTIVE:To quantify the risk and risk factors for cesarean delivery associated with medical and elective induction of labor in nulliparous women.

METHODS:A prospective cohort study was performed in nulliparous women at term with vertex singleton gestations who had labor induced at 2 obstetrical centers. Medical and elective indications and Bishop scores were recorded before labor induction. Obstetric and neonatal data were analyzed and compared with the results in women with a spontaneous onset of labor. Data were analyzed using univariate and multivariable regression modeling.

RESULTS:A total of 1,389 women were included in the study. The cesarean delivery rate was 12.0% in women with a spontaneous onset of labor (n = 765), 23.4% in women undergoing labor induction for medical reasons (n = 435) (unadjusted odds ratio [OR] 2.24; 95% confidence interval [CI] 1.64-3.06), and 23.8% in women whose labor was electively induced (n = 189) (unadjusted OR 2.29; 95% CI 1.53-3.41). However, after adjusting for the Bishop score at admission, no significant differences in cesarean delivery rates were found among the 3 groups. A Bishop score of 5 or less was a predominant risk factor for a cesarean delivery in all 3 groups (adjusted OR 2.32; 95% CI 1.66-3.25). Other variables with significantly increased risk for cesarean delivery included maternal age of 30 years or older, body mass index of 31 or higher, use of epidural analgesia during the first stage of labor, and birth weight of 3,500 g or higher. In both induction groups, more newborns required neonatal care, more mothers needed a blood transfusion, and the maternal hospital stay was longer.

CONCLUSION:Compared with spontaneous onset of labor, medical and elective induction of labor in nulliparous women at term with a single fetus in cephalic presentation is associated with an increased risk of cesarean delivery, predominantly related to an unfavorable Bishop score at admission.

LEVEL OF EVIDENCE:II-2.

OBJECTIVE: To examine the association between delivery method and mortality within 6 months of delivery among primiparas. METHODS: We conducted a population-based, retrospective cohort analysis using statewide, maternally linked birth certificate, hospital discharge, and death certificate data. The present cohort was all primiparas who gave birth to live-born infants in civilian hospitals in Washington State from January 1, 1987 through December 31, 1996 (n = 265,471). Odd ratios (OR) and 95% confidence intervals (CI) were calculated for overall mortality, pregnancy-related mortality, and pregnancy-unrelated mortality associated with delivery method. RESULTS: Thirty-two women (12.1 per 100,000 singleton live births) died within 6 months of delivery of their first child. Eleven of 32 deaths were pregnancy related (4.1 per 100,000 singleton live births, 95% CI 1.6, 6.5), and 21 of the 32 deaths were not pregnancy related (7.9 per 100,000 singleton live births, 95% CI 4.5, 11.3). The pregnancy-related mortality rate was higher among women delivered by cesarean (10.3/100,000) than among women delivered vaginally (2.4/100,000). In logistic regression analyses, women who had cesarean delivery were not at significantly higher risk of death overall after adjustment for maternal age (OR 1.7, 95% CI 0.3, 3.6), pregnancy-related death after adjustment for maternal age and severe preeclampsia (OR 2.2, 95% CI 0.6, 7.9), or pregnancy-unrelated death after adjustment for maternal age and marital status (OR 0.9, 95% CI 0.3, 2.7), relative to women who had vaginal delivery. CONCLUSION: Cesarean delivery might be a marker for serious preexisting morbidities associated with increased mortality risk rather than a risk factor for death in and of itself. Data from additional sources such as medical records and autopsy reports are necessary to disentangle preexisting mortality risk from risk associated solely with delivery method.

AIMS: to report the clinical outcomes of the first six months of operation of an innovative midwife-led normal birth unit (MNBU) in China in 2008, aiming to facilitate normal birth and enhance midwifery practice. SETTING: an urban hospital with 2000-3000 deliveries per year. METHOD: this study was part of a major action research project that led to implementation of the MNBU. A retrospective cohort and a questionnaire survey were used. The data were analysed thematically. PARTICIPANTS: the outcomes of the first 226 women accessing the MNBU were compared with a matched retrospective cohort of 226 women accessing standard care. In total, 128 participants completed a satisfaction questionnaire before discharge. MAIN OUTCOME MEASURE: mode of birth and model of care. FINDINGS: the vaginal birth rate was 87.6% in the MNBU compared with 58.8% in the standard care unit. All women who accessed the MNBU were supported by both a midwife and a birth companion, referred to as 'two-to-one' care. None of the women labouring in the standard care unit were identified as having a birth companion. DISCUSSION: the concept of 'two-to-one' care emerged as fundamental to women's experiences and utilisation of midwives' skills to promote normal birth and decrease the likelihood of a caesarean section. CONCLUSION: the MNBU provides an environment where midwives can practice to the full extent of their role. The high vaginal birth rate in the MNBU indicates the potential of this model of care to reduce obstetric intervention and increase women's satisfaction with care within a context of extraordinary high caesarean section rates. IMPLICATIONS FOR PRACTICE: midwife-led care implies a separation of obstetric care from maternity care, which has been advocated in many European countries.

AIMS: to report the clinical outcomes of the first six months of operation of an innovative midwife-led normal birth unit (MNBU) in China in 2008, aiming to facilitate normal birth and enhance midwifery practice. SETTING: an urban hospital with 2000-3000 deliveries per year. METHOD: this study was part of a major action research project that led to implementation of the MNBU. A retrospective cohort and a questionnaire survey were used. The data were analysed thematically. PARTICIPANTS: the outcomes of the first 226 women accessing the MNBU were compared with a matched retrospective cohort of 226 women accessing standard care. In total, 128 participants completed a satisfaction questionnaire before discharge. MAIN OUTCOME MEASURE: mode of birth and model of care. FINDINGS: the vaginal birth rate was 87.6% in the MNBU compared with 58.8% in the standard care unit. All women who accessed the MNBU were supported by both a midwife and a birth companion, referred to as 'two-to-one' care. None of the women labouring in the standard care unit were identified as having a birth companion. DISCUSSION: the concept of 'two-to-one' care emerged as fundamental to women's experiences and utilisation of midwives' skills to promote normal birth and decrease the likelihood of a caesarean section. CONCLUSION: the MNBU provides an environment where midwives can practice to the full extent of their role. The high vaginal birth rate in the MNBU indicates the potential of this model of care to reduce obstetric intervention and increase women's satisfaction with care within a context of extraordinary high caesarean section rates. IMPLICATIONS FOR PRACTICE: midwife-led care implies a separation of obstetric care from maternity care, which has been advocated in many European countries.

OBJECTIVE: Our purpose was to study the impact of labor onset and delivery mode on the risk of severe postpartum hemorrhage. STUDY DESIGN: This was a population-based study of 307,415 mothers who were registered in the Medical Birth Registry of Norway from 1999-2004. RESULTS: Severe postpartum hemorrhage occurred in 1.1% of all mothers and in 2.1% of those mothers with previous cesarean section delivery (CS). Compared with spontaneous labor, hemorrhage risk was higher for induction (odds ratio [OR], 1.71; 95% confidence interval [CI], 1.56-1.88) and prelabor CS (OR, 2.05; 95% CI, 1.84-2.29). The risk was 55% higher for emergency CS and half that for vaginal deliveries (OR, 0.48; 95% CI, 0.43-0.53), compared with prelabor CS. The highest risk was for emergency CS after induction in mothers with previous CS (OR, 6.57; 95% CI, 4.25-10.13), compared with spontaneous vaginal delivery in mothers with no previous CS. CONCLUSION: Induction and prelabor CS should be practiced with caution because of the increased risk of severe postpartum hemorrhage.

OBJECTIVE: The purpose of this study was to analyze reasons for postpartum readmission. STUDY DESIGN: We conducted a database analysis of readmissions within 6 weeks after delivery during 2007, with extended (180 day) analysis for pneumonia, appendicitis, and cholecystitis. Linear regression analysis, survival curve fitting, and Gehan-Breslow statistic with Holm-Sidak all-pairwise analysis for multiple comparisons were used. Probability values of<.05 were considered significant. RESULTS: Of 222,751 women delivered, 2655 women (1.2%) were readmitted within 6 weeks (0.83% vaginal delivery and 1.8% cesarean section delivery; P<.001). A high percentage of these readmittances occurred within the first 6 weeks: pneumonia (84%), appendicitis (43%), or cholecystitis (46%). Cumulative readmission rates were higher in the first 6 weeks after delivery than in the next 20 weeks (pneumonia curve gradient, 3.7 vs 0.11; appendicitis curve gradient, 1.1 vs 0.36; cholecystitis curve gradient, 6.6 vs 1.7). CONCLUSION: The cause of postpartum readmission is primarily infectious in origin. A recent pregnancy appears to increase the risk of pneumonia, appendicitis, and cholecystitis.

BACKGROUND: The percentage of United States' births delivered by cesarean section has increased rapidly in recent years, even for women considered to be at low risk for a cesarean section. The purpose of this paper is to examine infant and neonatal mortality risks associated with primary cesarean section compared with vaginal delivery for singleton full-term (37-41 weeks' gestation) women with no indicated medical risks or complications. METHODS: National linked birth and infant death data for the 1998-2001 birth cohorts (5,762,037 live births and 11,897 infant deaths) were analyzed to assess the risk of infant and neonatal mortality for women with no indicated risk by method of delivery and cause of death. Multivariable logistic regression was used to model neonatal survival probabilities as a function of delivery method, and sociodemographic and medical risk factors. RESULTS: Neonatal mortality rates were higher among infants delivered by cesarean section (1.77 per 1,000 live births) than for those delivered vaginally (0.62). The magnitude of this difference was reduced only moderately on statistical adjustment for demographic and medical factors, and when deaths due to congenital malformations and events with Apgar scores less than 4 were excluded. The cesarean/vaginal mortality differential was widespread, and not confined to a few causes of death. CONCLUSIONS: Understanding the causes of these differentials is important, given the rapid growth in the number of primary cesareans without a reported medical indication.

OBJECTIVE: The aim of the study was to compare the maternal and neonatal morbidity associated with elective cesarean sections with planned vaginal delivery. METHODS: A total of 178 women with elective cesarean section were compared with the next parity- and age-matched women presenting in spontaneous labor. Our analysis was restricted to a sample of low-risk obstetrical women. Maternal and neonatal outcomes were the main outcome variables of interest. Maternal morbidity outcome variables included wound infection, trauma, puerperal febrile morbidity and significant blood loss (>500 ml). Neonatal outcomes were captured by Apgar scores, cord pH as well as the occurrence of neonatal infections. RESULTS: A significantly higher rate of puerperal febrile morbidity (n = 46 vs. 14, p = 0.0001) and wound infections (n = 16 vs. 2, p = 0.0001) could be detected in the elective cesarean section group. Additionally, a significant blood loss>500 ml was more than twice as frequent in the cesarean section group (n = 22 vs. 10, p = 0.03) with non-significant lower postpartum hemoglobin levels being observed (10.4 vs. 11.2 g/dL, p>0.05). A significant increase for the use of iron supplementation (n = 146 vs. 122, p = 0.002), analgesics (n = 168 vs. 60, p = 0.0001) and antibiotics (n = 48 vs. 18, p = 0.0001) could be found in the puerperal period and hospital admission was prolonged in elective cesarean section (6.8 vs. 3.5 days, p = 0.0001). Additionally, problems in breastfeeding occurred more frequently in this group (n = 18 vs. 4, p = 0.002). Neonatal complications were generally low in both the groups with no significant differences being observed (p>0.05). CONCLUSION: The increased maternal morbidity in elective cesarean section included puerperal febrile morbidity, wound infections as well as breastfeeding problems in the postpartum period. Women should be sufficiently counseled regarding the increased risk of these complications.

PURPOSE: To ascertain any differences in foetomaternal outcomes in induced and spontaneous labour among nulliparous women delivering at term. METHODS: A retrospective matched cohort study consisting of 403 nulliparous women induced at≥292 days and 806 nulliparous women with spontaneous labour at 285-291 days. RESULTS: Compared to those in spontaneous labour, women who had induction of labour were three times more likely to have a caesarean delivery (OR 3.1, 95% CI 2.4-4.1; P < 0.001). Women who had induction of labour were 2.2 times more likely to have oxytocin augmentation (OR 2.2, 95% CI 1.7-2.8; P < 0.001), 3.6 times more likely to have epidural anaesthesia (OR 3.6, 95% CI 2.8-4.6; P < 0.001), 1.7 times more likely to have uterine hyperstimulation (OR 1.7, 95% CI 1.1-2.6), 2 times more likely to have a suspicious foetal heart rate trace (OR 2.0, 95% CI 1.5-2.6), 4.1 times more likely to have blood loss over 500 ml (OR 4.1, 95% CI 2.9-5.5; P < 0.001), and 2.9 times more likely to stay in hospital beyond 5 days (OR 2.9, 95% CI 1.5-5.6; P < 0.001). Babies born to mothers who had induction of labour were significantly more likely to have an Apgar score of<5 at 5 min and an arterial cord pH of<7.0. CONCLUSION: Compared to those with spontaneous labour, nulliparous women with induced labours are more likely to have uterine hyperstimulation, caesarean delivery, and babies with low Apgar scores. Nulliparous women should be made aware of this, as well as potential risks of expectant management during counseling.

OBJECTIVE: To assess the risks and benefits associated with caesarean delivery compared with vaginal delivery. DESIGN: Prospective cohort study within the 2005 WHO global survey on maternal and perinatal health. SETTING: 410 health facilities in 24 areas in eight randomly selected Latin American countries; 123 were randomly selected and 120 participated and provided data PARTICIPANTS: 106,546 deliveries reported during the three month study period, with data available for 97,095 (91% coverage). MAIN OUTCOME MEASURES: Maternal, fetal, and neonatal morbidity and mortality associated with intrapartum or elective caesarean delivery, adjusted for clinical, demographic, pregnancy, and institutional characteristics. RESULTS: Women undergoing caesarean delivery had an increased risk of severe maternal morbidity compared with women undergoing vaginal delivery (odds ratio 2.0 (95% confidence interval 1.6 to 2.5) for intrapartum caesarean and 2.3 (1.7 to 3.1) for elective caesarean). The risk of antibiotic treatment after delivery for women having either type of caesarean was five times that of women having vaginal deliveries. With cephalic presentation, there was a trend towards a reduced odds ratio for fetal death with elective caesarean, after adjustment for possible confounding variables and gestational age (0.7, 0.4 to 1.0). With breech presentation, caesarean delivery had a large protective effect for fetal death. With cephalic presentation, however, independent of possible confounding variables and gestational age, intrapartum and elective caesarean increased the risk for a stay of seven or more days in neonatal intensive care (2.1 (1.8 to 2.6) and 1.9 (1.6 to 2.3), respectively) and the risk of neonatal mortality up to hospital discharge (1.7 (1.3 to 2.2) and 1.9 (1.5 to 2.6), respectively), which remained higher even after exclusion of all caesarean deliveries for fetal distress. Such increased risk was not seen for breech presentation. Lack of labour was a risk factor for a stay of seven or more days in neonatal intensive care and neonatal mortality up to hospital discharge for babies delivered by elective caesarean delivery, but rupturing of membranes may be protective. CONCLUSIONS: Caesarean delivery independently reduces overall risk in breech presentations and risk of intrapartum fetal death in cephalic presentations but increases the risk of severe maternal and neonatal morbidity and mortality in cephalic presentations.

BACKGROUND: Data about maternal outcomes of elective Caesarean section in low-income countries are limited. AIMS: To estimate the maternal morbidity and mortality associated with elective Caesarean delivery at a Nigerian University hospital. METHODS: Retrospective analysis of all elective Caesarean deliveries at the Olabisi Onabanjo University Teaching Hospital, Sagamu, Nigeria (1990-2005). For each case of elective Caesarean delivery, four parturients who achieved non-operative vaginal delivery following spontaneous onset of labour were selected to serve as a referent group. Morbidity outcomes and mortality among women who had elective Caesarean delivery were compared with those of the referent group to estimate their comparative risks. Level of significance was put at P<0.05. RESULTS: A total of 164 elective Caesarean sections were performed out of 6882 deliveries (2.4%). All morbidities were more frequent among women who had elective Caesarean section compared to those who had vaginal delivery but only peripartum blood transfusion (11.6 vs 5.6%), puerperal febrile morbidity (11.0 vs 4.7%), unplanned readmission (4.3 vs 1.4%), mean fall in haemoglobin concentration (1.5 +/- 0.6 vs 0.5 +/- 0.7 g/dL) and mean hospital stay (13.3 +/- 8.8 vs 6.2 +/- 5.4 days) showed statistically significant differences. There was one maternal death among the elective Caesarean section group, giving a maternal mortality ratio of 6.1:1000 deliveries, which was not significantly different from 3.0:1000 deliveries in the referent group. CONCLUSION: Elective Caesarean delivery in this hospital is certainly accompanied by considerable maternal risks and should be offered to pregnant women with extreme caution. Efforts should be made to improve its safety by investigating and rectifying the factors responsible for the associated severe maternal complications.

OBJECTIVE: To describe postpartum maternal morbidity associated with mode of delivery in term, singleton pregnancies. METHODS: The Magee Obstetric Medical and Infant database was examined for the years 1995 to 2000. Patients were grouped into 6 types of delivery mode: spontaneous vaginal delivery, operative vaginal delivery, primary cesarean delivery without trial of labor, primary cesarean delivery with trial of labor, repeat cesarean delivery without trial of labor, and repeat cesarean delivery with trial of labor. Multivariable logistic regression provided odds ratios and 95% confidence intervals (CI) for morbidity by delivery mode adjusted for demographic characteristics and comorbidities. Spontaneous vaginal delivery was used as the referent group (odds ratio = 1). RESULTS: Of 32,834 subjects, 27,178 had vaginal delivery (operative = 4,908; spontaneous = 22,270) and 5,656 had cesarean delivery. Third- or fourth-degree lacerations occurred in 1,733 (7.8%) women who had spontaneous vaginal delivery compared with 1,098 (22.3%) who had operative vaginal delivery. Overall, 523 women (1.6%) had endometritis. Compared with spontaneous vaginal delivery, primary cesarean delivery with trial of labor conferred a 21.2-fold increased risk of endometritis (95% CI 15.4, 29.1). Even without trial of labor, women after primary cesarean delivery were 10.3 times more likely to develop endometritis (95% CI 5.9, 17.9) than after spontaneous vaginal delivery. The risk of transfusion was highest in women delivered by primary cesarean after labor, 4.2 times higher (95% CI 1.8, 10.1) than spontaneous vaginal delivery. The risk of pneumonia was 9.3 times higher (95% CI 3.4, 25.6) after repeat cesarean delivery with labor. Deep venous thromboses occurred in 15 (0.1%) after spontaneous vaginal delivery, 2 (0.04%) after operative vaginal delivery, and 12 (0.2%) after cesarean delivery. CONCLUSION: Compared with spontaneous vaginal delivery, cesarean delivery is associated with increased risks of endometritis, the need for transfusion, and pneumonia; however, these rates are lower than reported previously.

AIM: Pregnant women and their doctors need to know the maternal risks associated with different methods of delivery. There are few publications with ideal study design and adequate power to establish the relationship between maternal mortality and mode of delivery. The present retrospective cohort study was undertaken to evaluate the intrinsic risk of maternal death, directly attributed to cesarean delivery (CD) compared to vaginal delivery (VD), and to evaluate further the differential risk associated with antepartum and intrapartum CD. METHODS: After exclusion of medical or obstetric comorbidities, all deliveries, either vaginal or cesarean, were critically analyzed. The surviving mothers who had either method of delivery represented the two comparative groups. In the same period, relevant clinical information of every maternal death was noted. RESULTS: Twenty seven mothers died among the 13 627 CD mothers and 19 died among 30 215 VD mothers. CD was associated with a 3.01-fold increase in the risk of maternal mortality, compared with VD. The risk of antepartum CD differed from intrapartum CD (OR 1.73 vs OR 4.86). There was a significantly increased risk of maternal death from complications of anesthesia, puerperal infection and venous thromboembolism. The risk of death from postpartum hemorrhage did not differ significantly (95% CI 0.7-3.95). CONCLUSION: CD is increasingly perceived as a low-risk procedure. However, the present study clearly demonstrates that the risk of maternal death due to CD is significantly high, particularly when performed in labor. Therefore, CD should only be practiced when conditions clearly demand it.

BACKGROUND: The rate of elective primary cesarean delivery continues to rise, owing in part to the widespread perception that the procedure is of little or no risk to healthy women. METHODS: Using the Canadian Institute for Health Information's Discharge Abstract Database, we carried out a retrospective population-based cohort study of all women in Canada (excluding Quebec and Manitoba) who delivered from April 1991 through March 2005. Healthy women who underwent a primary cesarean delivery for breech presentation constituted a surrogate "planned cesarean group" considered to have undergone low-risk elective cesarean delivery, for comparison with an otherwise similar group of women who had planned to deliver vaginally. RESULTS: The planned cesarean group comprised 46,766 women v. 2,292,420 in the planned vaginal delivery group; overall rates of severe morbidity for the entire 14-year period were 27.3 and 9.0, respectively, per 1000 deliveries. The planned cesarean group had increased postpartum risks of cardiac arrest (adjusted odds ratio [OR] 5.1, 95% confidence interval [CI] 4.1-6.3), wound hematoma (OR 5.1, 95% CI 4.6-5.5), hysterectomy (OR 3.2, 95% CI 2.2-4.8), major puerperal infection (OR 3.0, 95% CI 2.7-3.4), anesthetic complications (OR 2.3, 95% CI 2.0-2.6), venous thromboembolism (OR 2.2, 95% CI 1.5-3.2) and hemorrhage requiring hysterectomy (OR 2.1, 95% CI 1.2-3.8), and stayed in hospital longer (adjusted mean difference 1.47 d, 95% CI 1.46-1.49 d) than those in the planned vaginal delivery group, but a lower risk of hemorrhage requiring blood transfusion (OR 0.4, 95% CI 0.2-0.8). Absolute risk increases in severe maternal morbidity rates were low (e.g., for postpartum cardiac arrest, the increase with planned cesarean delivery was 1.6 per 1000 deliveries, 95% CI 1.2-2.1). The difference in the rate of in-hospital maternal death between the 2 groups was nonsignificant (p = 0.87). INTERPRETATION: Although the absolute difference is small, the risks of severe maternal morbidity associated with planned cesarean delivery are higher than those associated with planned vaginal delivery. These risks should be considered by women contemplating an elective cesarean delivery and by their physicians.

BACKGROUND:Both gastrointestinal microbiota composition and cesarean section have been linked to atopic manifestations. However, results are inconsistent, and the hypothesized intermediate role of the microbiota in the association between birth mode and atopic manifestations has not been studied yet.

OBJECTIVES:We sought to investigate the relationship between microbiota composition, mode and place of delivery, and atopic manifestations.

METHODS:The Child, Parent and Health: Lifestyle and Genetic Constitution Birth Cohort Study included data on birth characteristics, lifestyle factors, and atopic manifestations collected through repeated questionnaires from birth until age 7 years. Fecal samples were collected at age 1 month (n = 1176) to determine microbiota composition, and blood samples were collected at ages 1 (n = 921), 2 (n = 822), and 6 to 7 (n = 384) years to determine specific IgE levels.

RESULTS:Colonization by Clostridium difficile at age 1 month was associated with wheeze and eczema throughout the first 6 to 7 years of life and with asthma at age 6 to 7 years. Vaginal home delivery compared with vaginal hospital delivery was associated with a decreased risk of eczema, sensitization to food allergens, and asthma. After stratification for parental history of atopy, the decreased risk of sensitization to food allergens (adjusted odds ratio, 0.52; 95% CI, 0.35-0.77) and asthma (adjusted odds ratio, 0.47; 95% CI, 0.29-0.77) among vaginally home-born infants was only found for children with atopic parents. Mediation analysis showed that the effects of mode and place of delivery on atopic outcomes were mediated by C difficile colonization.

CONCLUSION:Mode and place of delivery affect the gastrointestinal microbiota composition, which subsequently influences the risk of atopic manifestations.

BACKGROUND:Both gastrointestinal microbiota composition and cesarean section have been linked to atopic manifestations. However, results are inconsistent, and the hypothesized intermediate role of the microbiota in the association between birth mode and atopic manifestations has not been studied yet.

OBJECTIVES:We sought to investigate the relationship between microbiota composition, mode and place of delivery, and atopic manifestations.

METHODS:The Child, Parent and Health: Lifestyle and Genetic Constitution Birth Cohort Study included data on birth characteristics, lifestyle factors, and atopic manifestations collected through repeated questionnaires from birth until age 7 years. Fecal samples were collected at age 1 month (n = 1176) to determine microbiota composition, and blood samples were collected at ages 1 (n = 921), 2 (n = 822), and 6 to 7 (n = 384) years to determine specific IgE levels.

RESULTS:Colonization by Clostridium difficile at age 1 month was associated with wheeze and eczema throughout the first 6 to 7 years of life and with asthma at age 6 to 7 years. Vaginal home delivery compared with vaginal hospital delivery was associated with a decreased risk of eczema, sensitization to food allergens, and asthma. After stratification for parental history of atopy, the decreased risk of sensitization to food allergens (adjusted odds ratio, 0.52; 95% CI, 0.35-0.77) and asthma (adjusted odds ratio, 0.47; 95% CI, 0.29-0.77) among vaginally home-born infants was only found for children with atopic parents. Mediation analysis showed that the effects of mode and place of delivery on atopic outcomes were mediated by C difficile colonization.

CONCLUSION:Mode and place of delivery affect the gastrointestinal microbiota composition, which subsequently influences the risk of atopic manifestations.