Obstetrical interventions during labour and birth: an examination of effects on breastfeeding, neonatal mortality and children’s educational outcomes

Abstract

Background Obstetrical interventions during labour and birth are essential for perinatal care as part of any contemporary obstetric practice. Various underlying biological mechanisms have been proposed in linking obstetrical interventions during labour and birth with breastfeeding, infant’s health and children’s neurodevelopmental outcomes at later life. These mechanisms include changes in the gut microbiota composition, exposure to different levels of physical stress and stress hormone surges during labour and delivery, as well as epigenetic alteration of gene expression. The available evidence regarding the effect of obstetrical interventions during labour and birth on short-and long-term outcomes is limited. For instance, much of the available evidence was generated from high-income countries. Moreover, many of the previous studies were hampered by non-longitudinal study designs, small sample sizes and inconsistent findings, which may be due to suboptimal control of confounders and other biases. This thesis addresses these issues and utilises data from low-, middle- and high-income country settings.

Aims The overarching aim of this thesis is to examine the effect of obstetrical interventions during labour and birth on breastfeeding indicators (early initiation of breastfeeding, exclusive breastfeeding under 6 months, and children ever breastfed), neonatal mortality and children’s educational outcomes at eight years of age. Specifically, the aims include: -To estimate the prevalence and examine sociodemographic factors associated with caesarean section in Ethiopia. -To examine the changing temporal association between caesarean birth and neonatal death in Ethiopia from 2000 to 2016 as well as to provide an interpretation of the associations using the ‘Three Delays Model’ in the context of Ethiopia. -To investigate the effect of caesarean section on breastfeeding indicators—early initiation of breastfeeding (within 1 hour), exclusive breastfeeding under 6 months and children ever breastfed (at least once)—in each of the 33 countries in sub-Saharan Africa, as well as to summarise the magnitude of these within-country effects in an overall estimate using random-effects meta-analyses. -To examine the effect of Apgar scores of 0-5, 6, 7, 8 and 9 (compared with 10) on children’s educational outcomes at eight years of age. -To estimate the effect of elective induction of labour at 39 weeks of gestation as compared with expectant management on children’s educational outcomes at eight years of age. Methods Data for this thesis were drawn from the Demographic and Health Surveys (DHS) and the South Australian Early Childhood Data Project (SAECDP). The DHS are widely available high-quality data sources from low- and middle-income countries. The SAECDP is an established project that encompasses high-quality whole-of-population linked administrative data from state and federal sources in South Australia. The DHS data from 33 low- and middle-income countries in sub-Saharan Africa were used for the first three studies while the SAECDP data from South Australia were used for the final two studies in this thesis. The use of these two different data sources allowed this thesis to capture the effects of obstetrical interventions during labour and birth on women’s breastfeeding practices, neonatal health and children’s educational outcomes across diverse health system resource settings. For each study, the potential confounding was identified based on a priori subject matter and expert knowledge as well as through the use of the Directed Acyclic Graphs (DAGs). The analytic approaches to answer the aims of this thesis included the modified Poisson regression (Log-Poisson regression), augmented inverse probability weighed (AIPW) estimator, negative control outcome (a tool for detecting confounding and bias), random-effects meta-analysis as well as an application of the ‘Three Delays Model’.

Results In the first study, the national caesarean section rate increased from 0.7% in 2000 to 1.9% in 2016, with increases across 7 of the 11 administrative regions in Ethiopia. In the adjusted analysis, women who gave birth in a private health facility had a 78.0% higher risk of caesarean section (adjusted prevalence ratio (aPR) (95% CI) 1.78 (1.22 to 2.58) when compared to women who gave birth in public health facility. Having four or more births was associated with a lower risk of caesarean section compared to first births (aPR (95% CI) 0.36 (0.16 to 0.79)). In the second study, in Ethiopia, the adjusted prevalence ratios (aPR) for neonatal death among neonates born via caesarean section versus vaginal birth increased over time, from 0.95 (95% CI, 0.29 to 3.19) in 2000 to 2.81 (95% CI, 1.11 to 7.13) in 2016. The association between caesarean birth and neonatal death was stronger among rural women (aPR (95% CI) 3.43 (1.22 to 9.67)) and among women from the lowest quintile of household wealth (aPR (95% CI) 7.01 (0.92 to 53.36)) in 2016. On the other hand, the aggregate-level analysis revealed that increased caesarean section rates were correlated with a decreased proportion of neonatal deaths. In the third study, the within-country analyses in sub-Saharan Africa showed, compared with vaginal birth, caesarean section was associated with aPR for early initiation of breastfeeding that ranged from 0.24 (95% CI, 0.17 to 0.33) in Tanzania to 0.89 (95% CI, 0.78 to 1.00) in South Africa. The aPR for exclusive breastfeeding under 6 months ranged from 0.58 (95% CI; 0.34 to 0.98) in Angola to 1.93 (95% CI; 0.46 to 8.10) in Cote d'Ivoire, while the aPR for children ever breastfed ranged from 0.91 (95% CI, 0.82 to 1.02) in Gabon to 1.02 (95% CI, 0.99 to 1.04) in Gambia. The meta-analysis combining effect estimates from 33 countries in sub-Saharan Africa showed caesarean section was associated with a 46% lower prevalence of early initiation of breastfeeding (pooled aPR, 0.54 (95% CI, 0.48 to 0.60)). However, the pooled effects indicated there was little association with exclusive breastfeeding under 6 months (pooled aPR, 0.94 (95% CI; 0.88 to 1.01) and children ever breastfed (pooled aPR, 0.98 (95% CI; 0.98 to 0.99) among caesarean versus vaginally born children. In the fourth study, after adjusting for confounding, the risk differences comparing five-minute Apgar scores of 0-5 with Apgar score of 10 for children scoring at/below the national minimum standard (NMS) on the National Assessment Program—Literacy and Numeracy (NAPLAN) tests for each domain were: reading (0.07 (95% CI -0.16 to 0.29)), writing (0.27 (95% CI -0.14 to 0.68)), spelling (0.15 (95% CI -0.10 to 0.40)), grammar (0.04 (95% CI -0.21 to 0.29)) and numeracy (0.21 (95% CI -0.04 to 0.45)). Risk differences for children performing at/below the NMS were also evident when Apgar score of 6 were compared with Apgar score of 10. In the fifth (last) study, after adjusting for confounding, the average treatment effects (ATEs) comparing elective induction of labour at 39 weeks of gestation with expectant management for children scoring at/below the NMS on each domain were: reading (0.01 (95% CI -0.02 to 0.03)), writing (0.02 (95% CI -0.00 to 0.04)), spelling (0.01 (95% CI -0.01 to 0.04)), grammar (0.02 (95% CI -0.01 to 0.04)) and numeracy (0.03 (95% CI 0.00 to 0.05)).

Conclusions The findings from this thesis present a comprehensive analyses of the effect of obstetrical interventions during labour and birth on breastfeeding, neonatal mortality and children’s educational outcomes at eight years of age by utilising data from low-, middle-, and high-income countries. The findings of Study 1 highlighted that there were large disparities in caesarean section use in Ethiopia, demonstrating unequal access. The results from Studies 2, 3 and 4 suggest that obstetrical interventions during labour and birth (caesarean section and Apgar score) have an influence on neonatal mortality, breastfeeding and children’s educational outcomes at later age. However, the findings of Study 5 suggest that elective induction of labour at 39 weeks of gestation as compared with expectant management did not affect children’s educational outcomes at eight years of age.