Maternal education and offspring birth weight for gestational age: the mediating effect of smoking during pregnancy.

BACKGROUND: Small for gestational age (SGA) birth weight, a risk factor for infant mortality and delayed child development, is associated with maternal educational attainment. Maternal tobacco smoking during pregnancy could contribute to this association. We aimed to quantify the contribution of maternal smoking during pregnancy to social inequalities in child birth weight for gestational age (GA). METHODS: Data come from the French nation-wide ELFE cohort study, which included 17 155 singletons. Birth weights for GA were calculated using z-scores. Associations between maternal educational attainment, tobacco smoking during pregnancy and child birth weight for GA were ascertained using mediation analysis. Mediation analyses were also stratified by maternal pre-pregnancy body mass index. RESULTS: Low maternal educational attainment was associated with an increased odd of tobacco smoking during pregnancy [adjusted OR (ORa) = 2.58 (95% CI 2.34-2.84)] as well as a decrease in child birth weight for GA [RRa = 0.94 (95% CI 0.91-0.98)]. Tobacco smoking during pregnancy was associated with a decrease in offspring birth weight for GA [RRa = 0.73 (95% CI 0.70-0.76)]. Mediation analysis suggests that 39% of the effect of low maternal educational attainment on offspring birth weight for GA was mediated by smoking during pregnancy. A more important direct effect of maternal educational attainment on child birth weight for GA was observed among underweight women [RRa = 0.82 (95% CI 0.72-0.93)]. CONCLUSIONS: The relationship between maternal educational attainment and child birth weight for GA is strongly mediated by smoking during pregnancy. Reducing maternal smoking could lessen the occurrence of infant SGA and decrease socioeconomic inequalities in birth weight for GA.

Which modifiable prenatal factors mediate the relation between socio-economic position and a child's weight and length at birth?

Although several studies have shown a positive association between socio-economic position and size at birth, not enough is known about the modifiable factors that may be involved. We aimed to investigate whether maternal prepregnancy body mass index (BMI), smoking, diet, and depression during pregnancy mediate the positive association between maternal education and birth size. Weight and length z-scores specific for gestational age and sex were calculated for 1,500 children from the EDEN mother-child cohort. A mediation analysis of the associations between maternal education and birth size was conducted with a counterfactual method, adjusted for recruitment centre, parity, maternal height, and age. In the comparison of children of mothers with low versus intermediate education levels, maternal smoking during pregnancy explained 52% of the total effect of education on birth weight. Similar findings were observed with birth length z-score (37%). The comparison of children of mothers with high versus intermediate education levels yielded a non-significant total effect, which masked opposite mediating effects by maternal BMI and smoking during pregnancy on both birth weight and length. Prepregnancy BMI and maternal smoking during pregnancy mediate the positive association between maternal education and birth weight and length z-scores. These mediators, however, act in opposite directions, thereby masking the extent to which healthy prenatal growth is socially differentiated.

Risk Factors for Infant Colonization by Hypervirulent CC17 Group B Streptococcus: Toward the Understanding of Late-onset Disease.

BACKGROUND: In infants, the mode of acquisition of CC17 group B Streptococcus (GBS), the hypervirulent clone responsible for late-onset disease (LOD), remains elusive. METHODS: In a prospective multicenter study in France, we evaluated GBS colonization in mother-baby pairs with 2 months of follow-up between 2012 and 2015. Criteria included positivity for GBS colonization at antenatal screening or at delivery. Maternal vaginal samples and infant oral cavity and stool samples were analyzed at delivery, 21 ± 7 days (D21), and 60 ± 7 days (D60) post-delivery. RESULTS: A total of 890 mother-baby pairs were analyzed. GBS colonized 7%, 21%, and 23% of the infants at birth, D21, and D60, respectively, of which 10%, 11%, and 13% were identified as CC17 GBS. Concordance between maternal and infant GBS type was 96%. At D21, the main risk factors for infant colonization by GBS were simultaneous maternal colonization of the vagina (odds ratio [OR], 4.50; 95% confidence interval [CI], 1.69-15.61) and breast milk (OR, 7.93; 95% CI, 3.81-17.14). Importantly, 38% (95% CI, 23%-56%) of infants colonized by CC17 GBS appeared colonized for the first time at D60 vs 18% (95% CI, 14%-24%; P < .049) of infants colonized by non-CC17 GBS. Multivariate analysis showed a higher risk for de novo infant colonization by CC17 at D60 than by other GBS (OR, 2.45; 95% CI, 1.02-5.88). CONCLUSIONS: The high incidence of CC17 GBS in LOD is likely due to an enhanced post-delivery mother-to-infant transmission.

Population-based study of cognitive outcomes in congenital heart defects.

OBJECTIVE: To characterise and compare cognitive outcomes in children with operated (open-heart surgery) and non-operated (catheter-based interventions only or no intervention) congenital heart defects (CHD) and to determine associated risk factors. DESIGN: This prospective population-based study reports outcomes of 3-year-old children with CHD with or without open-heart surgery. MAIN OUTCOME MEASURES: Standardised cognitive scores (mean scores and proportions below normative values) were assessed with the Kaufman Assessment Battery for Children II. We analysed demographic, perinatal and operative variables as predictors of cognitive outcomes. RESULTS: 419 children participated (154 with open-heart surgery; 265 without surgery). Global cognitive scores did not differ between the groups. Compared with the non-operated group, children who underwent surgery obtained lower scores in expressive language (p=0.03) and logical reasoning (p=0.05). When compared with test norms, the frequency of global cognitive scores >1 SDs below the expected mean was higher in the surgical group (25% vs 16% in the general population) (p=0.03). A higher-than-expected proportion of children in the non-operated group scored >2 SDs below the expected mean (7% vs 2%) (p=0.05). Being small for gestational age (SGA) significantly increased the risk of cognitive impairment in the surgical group, after adjustments for multiple covariates including maternal education, complexity of the CHD and operative-related variables (adjusted OR=5.9; 95% CI (1.7 to 20.1)). CONCLUSIONS: Despite mean scores within the normative range, a high proportion of preschool children with CHD with or without surgery are at early cognitive risk. SGA is a strong predictor of the neurodevelopmental prognosis in CHD.

Impact of prenatal diagnosis on survival of newborns with four congenital heart defects: a prospective, population-based cohort study in France (the EPICARD Study).

OBJECTIVES: (1) Assess the population-level probability of prenatal diagnosis and termination of pregnancy for fetal anomaly for four major congenital heart defects; (2) Examine, using population-based data, the relation between timing of (prenatal vs postnatal) diagnosis and risk of infant (ie, < 1 year) mortality for four major congenital heart defects (CHDs). DESIGN: Population-based cohort (the EPIdémiologie des CARDiopathies congénitales) study. SETTING: Greater Paris area (Paris and its surrounding suburbs). PATIENTS: Three hundred and fifty-four cases of four major CHDs, including functionally univentricular heart (FUH, N=132), d-transposition of great arteries (d-TGA, N=85), tetralogy of Fallot (TOF, N=60) and coarctation of aorta (CoA, N=77). Statistical analysis included the Mantel-Haenszel method and a test of homogeneity of risk ratios. RESULTS: Approximately 95% of FUH, more than two-thirds of d-TGA and TOF, and 40% of CoA were prenatally diagnosed. Overall, we did not find any statistically significant association between timing of (prenatal vs postnatal) diagnosis of CHD and risk of infant mortality (Mantel-Haenszel risk ratio 1.1, 95% CI 0.5 - 2.7); and the differences between the risk ratios of the association between prenatal diagnosis and infant mortality across the four CHDs was not statistically significant. CONCLUSION: These results imply that at least in the settings where specialised services are readily available, survival may no longer be the most relevant outcome, or the best criterion, for evaluating the impact of prenatal diagnosis on the outcome of CHD. The beneficial effects of prenatal diagnosis may be better sought by looking at more 'subtle' or long-term neurodevelopmental outcomes.