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Background: Beneficial effects of greenness on birth outcomes have been reported, but few studies have investigated the associations in both urban and non-urban settings. We aimed to evaluate and compare linear and nonlinear associations between greenness and birth outcomes in urban and non-urban settings.Methods: From October 2015 to December 2018, participants were recruited into the Maoming Birth Cohort Study. A total of 11 258 live birth records were obtained. Greenness exposure was assessed using the normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI). Linear regression and nonlinear restricted cubic spline models were implemented to investigate the associations between greenness and birthweight, birth length, gestational age, preterm birth, low birthweight, small for gestational age and the potential for effect variation under urban or non-urban settings, after adjusting for covariates.Results: A 0.1-unit increase in NDVI-500m was significantly associated with an increase of 35.4 g in birthweight [95% confidence interval (CI): 13.2, 57.7], 0.15 cm in birth length (95% CI: 0.03, 0.26), 0.88 days in gestational age (95% CI: 0.05, 1.71) and lower odds of low birthweight [odds ratio (OR) = 0.69, 95% CI: 0.56, 0.85] and preterm birth (OR = 0.70, 95% CI: 0.58, 0.85). No association with head circumference was observed. For all outcomes, no significant linear associations were observed among non-urban dwellers. Inversed 'U-shaped' associations between greenness exposure and birth outcomes were observed in the total study population.Conclusions: Greenness exposure was associated with increased gestational age, birthweight and birth length in urban dwellers. Nonlinear associations assessed by restricted cubic splines suggested that health benefits could be larger when increasing greenness levels from low to medium compared with increasing greenness from medium to high levels. Further studies adopting nonlinear methods are warranted to verify our findings. [ABSTRACT FROM AUTHOR]

Background: Mothers' smoking during pregnancy increases asthma risk in their offspring. There is some evidence that grandmothers' smoking may have a similar effect, and biological plausibility that fathers' smoking during adolescence may influence offspring's health through transmittable epigenetic changes in sperm precursor cells. We evaluated the three-generation associations of tobacco smoking with asthma.Methods: Between 2010 and 2013, at the European Community Respiratory Health Survey III clinical interview, 2233 mothers and 1964 fathers from 26 centres reported whether their offspring (aged ≤51 years) had ever had asthma and whether it had coexisted with nasal allergies or not. Mothers and fathers also provided information on their parents' (grandparents) and their own asthma, education and smoking history. Multilevel mediation models within a multicentre three-generation framework were fitted separately within the maternal (4666 offspring) and paternal (4192 offspring) lines.Results: Fathers' smoking before they were 15 [relative risk ratio (RRR) = 1.43, 95% confidence interval (CI): 1.01-2.01] and mothers' smoking during pregnancy (RRR = 1.27, 95% CI: 1.01-1.59) were associated with asthma without nasal allergies in their offspring. Grandmothers' smoking during pregnancy was associated with asthma in their daughters [odds ratio (OR) = 1.55, 95% CI: 1.17-2.06] and with asthma with nasal allergies in their grandchildren within the maternal line (RRR = 1.25, 95% CI: 1.02-1.55).Conclusions: Fathers' smoking during early adolescence and grandmothers' and mothers' smoking during pregnancy may independently increase asthma risk in offspring. Thus, risk factors for asthma should be sought in both parents and before conception.Funding: European Union (Horizon 2020, GA-633212). [ABSTRACT FROM AUTHOR]