Mediation analysis of gestational age, congenital heart defects, and infant birth-weight

Prevalence and Infant Mortality of Major Congenital Malformations Stratified by Birthweight

BACKGROUND

Low birthweight and major congenital malformations (MCMs) are key causes of infant mortality.

OBJECTIVES

The aim of this study was to explore the prevalence of MCMs in infants with low and very low birthweight and analyze the impact of MCMs and birthweight on infant mortality.

METHODS

We determined prevalence and infant mortality of 28 life-threatening MCMs in very-low-birthweight (<1,500 g, VLBW), low-birthweight (1,500-2,499 g, LBW), or normal-birthweight (≥2,500 g, NBW) infants in a cohort of 2,727,002 infants born in Germany in 2006-2017, using de-identified administrative data of the largest statutory public health insurance system in Germany.

RESULTS

The rates of VLBW, LBW, and NBW infants studied were 1.3% (34,401), 4.0% (109,558), and 94.7% (2,583,043). MCMs affected 0.5% (13,563) infants, of whom >75% (10,316) had severe congenital heart disease. The prevalence (per 10,000) of any/cardiac MCM was increased in VLBW (286/176) and LBW (244/143), as compared to NBW infants (38/32). Infant mortality rates were significantly higher in infants with an MCM, as opposed to infants without an MCM, in each birthweight group (VLBW 28.5% vs. 11.5%, LBW 16.7% vs. 0.9%, and NBW 8.6% vs. 0.1%). For most MCMs, observed survival rates in VLBW and LBW infants were lower than expected, as calculated from survival rates of VLBW or LBW infants without an MCM, and NBW infants with an MCM.

CONCLUSIONS

Infants with an MCM are more often born with LBW or VLBW, as opposed to infants without an MCM. Many MCMs carry significant excess mortality when occurring in VLBW or LBW infants.

Parental non-hereditary teratogenic exposure factors on the occurrence of congenital heart disease in the offspring in the northeastern Sichuan, China

Nonhereditary factors play an important role in the occurrence of congenital heart disease (CHD). This study was to explore the possible parental nonhereditary exposure factors relevant to the occurrence of CHD in the northeastern Sichuan area. A total of 367 children with CHD and 367 children without congenital malformations aged 0 to 14 years old were recruited from the Affiliated Hospital of North Sichuan Medical College and Nanchong Central Hospital between March 2016 and November 2018. This study was designed as a case-control study with 1:1 frequency matching, in which the parents of cases and controls were interviewed with the same questionnaire according to the gestational age of the child, maternal age during pregnancy and the same maternal race/ethnicity. Then, 322 matched case-control pairs were analysed by SPSS 22. Thirty-one suspicious factors were entered into the binary logistic regression analysis after univariate regression analysis of 55 factors (alpha = 0.05). The analysis results showed that 7 factors were significantly associated with the occurrence of CHD. Thus, augmenting maternal mental healthcare, improving the quality of drinking water, obtaining adequate nutrition, maintaining a healthy physical condition during pregnancy, enhancing parents’ level of knowledge and maintaining a healthy lifestyle may lower the occurrence of CHD.

Maternal exposure to ambient PM10 during pregnancy increases the risk of congenital heart defects: Evidence from machine learning models

Previous research suggested an association between maternal exposure to ambient air pollutants and risk of congenital heart defects (CHDs), though the effects of particulate matter ≤10μm in aerodynamic diameter (PM₁₀) on CHDs are inconsistent. We used two machine learning models (i.e., random forest (RF) and gradient boosting (GB)) to investigate the non-linear effects of PM₁₀ exposure during the critical time window, weeks 3-8 in pregnancy, on risk of CHDs. From 2009 through 2012, we carried out a population-based birth cohort study on 39,053 live-born infants in Beijing. RF and GB models were used to calculate odds ratios for CHDs associated with increase in PM₁₀ exposure, adjusting for maternal and perinatal characteristics. Maternal exposure to PM₁₀ was identified as the primary risk factor for CHDs in all machine learning models. We observed a clear non-linear effect of maternal exposure to PM₁₀ on CHDs risk. Compared to 40μgm^-3, the following odds ratios resulted: 1) 92μgm^-3 [RF: 1.16 (95% CI: 1.06, 1.28); GB: 1.26 (95% CI: 1.17, 1.35)]; 2) 111μgm^-3 [RF: 1.04 (95% CI: 0.96, 1.14); GB: 1.04 (95% CI: 0.99, 1.08)]; 3) 124μgm^-3 [RF: 1.01 (95% CI: 0.94, 1.10); GB: 0.98 (95% CI: 0.93, 1.02)]; 4) 190μgm^-3 [RF: 1.29 (95% CI: 1.14, 1.44); GB: 1.71 (95% CI: 1.04, 2.17)]. Overall, both machine models showed an association between maternal exposure to ambient PM₁₀ and CHDs in Beijing, highlighting the need for non-linear methods to investigate dose-response relationships.

A Bayesian finite mixture of bivariate regression model for causal mediation analyses

Building on the work of Schwartz et al, Joint Bayesian analysis of birthweight and censored gestational age using finite mixture models in Statistics in Medicine, we propose a Bayesian finite mixture of bivariate regression model for causal mediation analyses. Using an identifiability condition within each component of the mixture, we express the natural direct and indirect effects of the exposure on the outcome as functions of the component-specific regression coefficients. On the basis of simulated data, we examine the behavior of the model for estimating these effects in situations where the associations between exposure, mediator, and outcome are confounded or not. Additionally, we demonstrate that this mixture model can be used to account for heterogeneity arising through unmeasured binary or categorical mediator-outcome confounders. Considering gestational age as a potential mediator, we then illustrate our mediation mixture model to estimate the natural direct and indirect effects of exposure to inhaled corticosteroids during pregnancy on birthweight using a cohort of asthmatic women from the province of Quebec (Canada).

Deaths and end-of-life decisions differed between neonatal and paediatric intensive care units at the same children's hospital

AIM

We compared neonatal deaths and end-of-life decisions in a neonatal intensive care unit (NICU) and paediatric intensive care unit (PICU) in a Dutch tertiary children's hospital.

SUBJECTS

All 235 full-term infants who died within 28 days of life between 2003 and 2013 in the NICU (n = 199) and PICU (n = 36) were retrospectively studied.

RESULTS

The median length of stay was three days in the NICU and seven days in the PICU (p = 0.003). The main reasons for NICU stays were asphyxia (52.8%) and congenital malformations (42.2%), and in the PICU, they were congenital malformations (97.2%) and primarily cardiac problems (83.3%, p < 0.001). The median age of death was three days in the NICU and eight days in the PICU (p < 0.001), and mortality despite full intensive care treatment was 4.0% and 25.0%, respectively. Intensive treatment was discontinued because of poor survival chances in 25.1% of NICU and 52.8% of PICU cases (p < 0.001), and care was redirected because of expected poor quality of life in 70.9% and 22.2%, respectively.

CONCLUSION

Differences between the age at death and end-of-life decisions were found between full-term infants in the NICU and PICU in the same children's hospital. Underlying disorders and doctors' attitudes may have played a role.

The relationship between birth weight and congenital heart disease at Ahmed Gasim Cardiac Centre, Bahri, Sudan

Low birth weight is a known comorbidity of congenital heart disease (CHD). This study examines the relationship between CHD and birth weight of singletons, while attempting to remove factors that influence birth weight, and assesses the impact of CHD on growth in later life. The main objective is to study the relationship between birthweight and CHD. This is a cross-sectional study of 141 samples, covering all patients who were referred to the Paediatric Echocardiography Lab at Ahmed Gasim Cardiac Centre between September and October 2016. Infants with genetic syndromes or other major extracardiac abnormalities were excluded. The findings of this study clearly demonstrate that infants with CHD are more likely to be of low birth weight than the general Sudanese population, by a factor of 2.6. Of the sample, 31.9% were born with low or very low birthweight. The mean birth weight of the cases was 2.59 kg, which is 17.3% and 542.4 g less than the national average. CHD that cause a decrement in birth weight in a descending order of severity were atrial septal defect (-721 g/23%), patent ductus arteriosus (-669 g/21%), ventricular septal defect (-610 g/19%), pulmonary stenosis (-548 g/13%) and tetralogy of Fallot (248 g/8%). Pre/postnatal growth impairment is a common feature among children with CHD. No statistically significant relationship was found between the degree of birth weight/weight to age decrement and the specific type of hemodynamic disturbance. Our results are comparable to other studies that have been undertaken. However, Sudanese patients display larger birthweight deficits than other populations.