This study aimed to investigate the association between family characteristics and adherence to the EAT-Lancet dietary recommendations in 7-year-old children. This is a prospective birth cohort study with 2125 children from Generation XXI (Porto, Portugal), who provided 3-day food diaries at age 7, used to assess habitual food consumption. At the age of 4, maternal diet was assessed using a Food Frequency Questionnaire, and a diet quality score was calculated (higher scores indicating a better maternal diet), and parental–child feeding practices were assessed with the Child Feeding Questionnaire. Adherence to the EAT-Lancet dietary recommendations was evaluated using the World Index for Sustainability and Health (WISH) at the age of 7 years, previously adapted to paediatric age. Hierarchical linear regression models (consecutive addition of blocks of variables based on a theoretical framework) were employed to evaluate the associations between family characteristics and adherence to the WISH at age 7 (β regression coefficients and the respective 95 % confidence intervals (95 % CI)). Higher maternal age and education at child’s birth were associated with increased adherence to the WISH at age 7 (β = 0·018, 95 % CI 0·005, 0·031; β = 0·038, 95 % CI 0·024, 0·053, respectively). A better maternal diet quality and using more restrictive practices on child’s diet, at 4 years old, were both associated with higher scoring in the WISH at 7 years old (β = 0·033, 95 % CI 0·018, 0·049; β = 0·067, 95 % CI 0·009, 0·125, respectively). Early maternal sociodemographic and diet quality play a significant role in influencing the adherence to a healthy and environmentally sustainable dietary pattern at school-age.

Previous studies have shown that mothers of naturally conceived dizygotic (DZ) twins tend to be taller, older, and smoke more than mothers of naturally conceived monozygotic (MZ) twin and mothers of singletons. Here, we investigate whether mothers of naturally conceived DZ twins differ from mothers who conceived their DZ twins after medically assisted reproduction (MAR) in eight maternal traits related to fertility based on observational survey data. We include data from 33,648 mothers from the Netherlands Twin Register (NTR) and 1660 mothers of twins from the Norwegian Mother, Father and Child Cohort Study (MoBA). We contrast mothers of naturally conceived DZ twins with mothers of MAR DZ twins. Next, we further segment the MAR group into mothers who underwent hormonal induction of ovulation but not in vitro fertilization (IVF) and those who IVF twins, comparing them both to each other and against the mothers of naturally conceived DZ twins. Mothers of naturally conceived DZ twins smoke more often, differ in body composition, have a higher maternal age and have more offspring before the twins than mothers of MZ twins. Compared to MAR DZ twin mothers, mothers of naturally conceived DZ twins have fewer miscarriages, lower maternal age and increased height, more offspring and are more often smokers. BMI before the twin pregnancy is similar in both natural and MAR DZ twin mothers. Mothers who received hormonal induction of ovulation (OI) have a lower maternal age, fewer miscarriages, and a higher number of offspring before their twin pregnancy than twin mothers who received IVF and/or intracytoplasmic sperm injection (ICSI) treatments. Our study shows that twin mothers are a heterogenous group and the differences between twin mothers should be taken into account in epidemiological and genetic research that includes twins.