French National Birth Cohort Research Articles

Early childcare type and child development at age 3.5 years, data from the French ELFE cohort

Abstract Background Early childcare has been linked to child development in some countries. The aim of this study is to evaluate the impact of early childcare in the French context, where children can attend different types of childcare facilities prior to age 3 when they enter kindergarten, and development at age 3.5 years. Methods 10,683 children from the ELFE French national birth cohort were classified into 4 groups depending on their main type of childcare between birth and age three: childminder (n = 5,014), centre-based childcare (n = 2,583), informal childcare (n = 777) and parents only (n = 2,465). Children's development was measured with the short form of the Child Development Inventory (CDI) via parents-reports at age 3.5 years. The CDI score was transformed into a Development Quotient (DQ) taking into account the child's age, and global developmental delay was defined as DQ < 90. Missing data was imputed by Fully Conditional Multiple Imputation with 10 imputations. Multinomial analyses were carried out adjusted by Inverse Probability Weighting based on Propensity Scores calculated using main selection and confounding variables. Results Compared to children who were cared for by parents only, children who were cared for by a childminder or in a centre-based childcare had a higher DQ (103.0 and 104.8 respectively) as well as a lower likelihood of global developmental delay (propensity-score weighted OR = 0.84, [95% CI 0.70-1.01] and propensity-score weighted OR = 0.54, [95% CI 0.44-0.66]) respectively. Conclusions In the French context, early centre-based childcare attendance is significantly associated with a lower risk of global child delay. Policies should make centre-based childcare more accessible to a broader number of children. Key messages • Early childcare type is linked to child development in France. • Children in centre-based childhood had a lower likelihood of developmental delay compared to those looked after by parents only.

An association between maternal weight change in the year before pregnancy and infant birth weight: ELFE, a French national birth cohort study

Women (n =16,395; 26% overweight or obese) from the ELFE French national birth cohort were categorised into 3 groups by self-reported weight change during the year before pregnancy: weight loss >5 kg; stable weight; and weight gain >5 kg.

Infant feeding practices and sleep at 1 year of age in the nationwide ELFE cohort.

Sleep problems reported by parents affect 20% to 30% of infants. Few studies focused on the longitudinal association between infant feeding practices and sleep, especially in France. Analyses were based on 8,696 infants from the French national birth cohort ELFE. Collection of feeding practices from birth to 10 months allowed for the identification of trajectories of use of baby cereals and thickened formula by group‐based trajectory modelling and calculation of duration of any breastfeeding (BF) and age at complementary feeding introduction (CFI) excluding baby cereals. Total sleep duration (TSD), night waking (NW) and sleep onset difficulties (SOD) were reported at age 1. Associations between feeding and sleep were tested by multinomial logistic regressions. BF duration ≥6 months was associated with parent‐reported frequent NW, SOD and TSD ≤ 12 h/24 h at age 1. For TSD and SOD, this association was no longer significant after accounting for parental sleep‐related practices. Early use of baby cereals (≤5 months) was associated with poor sleep. Early CFI (<4 months) was associated with shorter TSD and SOD but not NW. Early use of thickened formula (only <6 months) was related to poor sleep at age 1 (NW and SOD), whereas late (around 6 months) use of thickened formula was associated with better sleep. BF duration ≥6 months was related to poor sleep at age 1 but not after adjustment on 1‐year parental sleep‐related practices except for NW. The use of baby cereals or early CFI was not related to better sleep at age 1.

Cohort Profile: The French national cohort of children (ELFE): birth to 5 years.

ELFE is the first French national birth cohort. Its objective is to study determinants of the development, health and socialization of children from birth to adulthood through a multidisciplinary approach. A total of 18 329 children were recruited at birth in a random sample of maternity units in metropolitan France during 25 selected days of 2011 spread over the year. Follow-up in the first 5 years consisted of telephone interviews of both parents of the child at age 2 months and 1 year and 2 years, and of one parent at age 3.5 years; a home visit at age 3.5 years; questionnaires to the child’s physician at age 2 years, the child’s nursery school doctor at age 3 to 4 years, and the child’s nursery schoolteacher at age 4 years. Participation rates at the age 2-month, 1- and 2-year and 3.5-year parental interviews were 92%, 86%, 82% and 80%, espectively, of contacted participants. The main categories of data collected concern: sociodemographic characteristics; family life; parental health, behaviour and life values; child development and health; child school performance, behaviour, and socialization; day care and school; and childhood environmental exposures. The ELFE has an open-data policy after an 18-month exclusivity period following each release of new data. The data-access policy, study protocols, questionnaires and data catalogue can be found online: [https://www.ELFE-france.fr/en/]

Multiple pesticides in mothers' hair samples and children's measurements at birth: Results from the French national birth cohort (ELFE).

A growing body of studies now suggests that the general population is continuously and ubiquitously exposed to numerous pesticides. However, studies investigating the possible role of environmental exposure to pesticides on fetal growth have focused on a limited set of substances, despite the hundreds of modern pesticides currently available. To explore the relation between maternal hair concentrations of 64 pesticides and metabolites and their newborns' measurements at birth, with data from the ELFE French nationwide birth cohort. We measured 64 compounds (10-100% detection) in bundles of hair 9 cm long collected at birth from 311 women who gave birth in France in 2011. We assessed their associations with birth weight, length, and head circumference, adjusted for potential confounders, and used elastic net regularization to simultaneously select the strongest predictors of measurements at birth. Selected variables were multiply imputed for missing values, and unpenalized estimators were assessed by standard linear regression. We observed statistically significant associations between maternal hair concentrations of seven pesticides or pesticide metabolites and birth measurements (weight: fipronil sulfone; length: TCPy, bitertanol, DEP, and isoproturon; head circumference: tebuconazole and prochloraz). Analyses restricted to boys identified 12 additional compounds: 8 independently associated with birth weight (3Me4NP, DCPMU, DMST, fipronil, mecoprop, propoxur, fenhexamid, and thiabendazole), 2 with birth length (dieldrin and β-endosulfan), and 6 with head circumference (β-endosulfan, β-HCH, fenuron, DCPMU, propoxur, and thiabendazole). Our results suggest that prenatal exposure to 19 pesticides or metabolites from various chemical families may influence measurements at birth. As with any exploratory research findings, results should be interpreted cautiously, until they are replicated or verified by further epidemiological or mechanistic studies.

An association between maternal weight change in the year before pregnancy and infant birth weight: ELFE, a French national birth cohort study.

BackgroundWeight-control interventions in pregnant women with overweight or obesity have limited effectiveness for fetal growth and birth outcomes. Interventions or prevention programs aiming at the pre-pregnancy period should be considered. However, how the woman’s weight change before pregnancy affects fetal growth is not known. We investigated the association between weight change over the year before pregnancy and birth weight.Methods and findingsWe used the inclusion data of 16,395 women from the ELFE French national birth cohort, a nationally representative cohort in which infants were enrolled at birth with their families in 2011. Maternal weight change was self-reported and classified into 3 groups: moderate weight variation or stable weight, weight loss > 5 kg, and weight gain > 5 kg or both weight loss and gain > 5 kg. Multiple linear regression models were used to investigate the association between pre-pregnancy weight change and a birth weight z-score calculated according to the French Audipog reference, adjusted for a large set of maternal characteristics. The analyses were stratified by maternal body mass index (BMI) at conception (<25 versus ≥25 kg/m2) and adjusted for BMI within these categories. We used the MacKinnon method to test the mediating effect of gestational weight gain (GWG) on these associations. Mother’s mean age was 30.5 years, 87% were born in France, and 26% had overweight or obesity. For women in either BMI category at conception, GWG was more than 2 kg higher, on average, for women with weight loss before pregnancy than for women with stable weight or moderate weight variation. For women with BMI < 25 kg/m2 at conception, birth weight was significantly higher with weight loss than stable weight before pregnancy (β = 0.08 [95% CI 0.02; 0.14], p = 0.01), and this total effect was explained by a significant mediating effect through GWG. For women with BMI ≥ 25 kg/m2 at conception, birth weight was not associated with pre-pregnancy weight loss during the year before pregnancy. Mediation analysis revealed that in these women, the direct effect of pre-pregnancy weight loss that would have resulted in a smaller birth weight z-score (β = −0.11 [95% CI −0.19; −0.03], p = 0.01) was cancelled out by the GWG. The mediating effect of GWG was even higher when weight loss resulted from a restrictive diet in the year before pregnancy. Weight gain before pregnancy was not associated with birth weight. Although we included a large number of women and had extensive data, the only potential cause of pre-pregnancy weight loss that was investigated was dieting for intentional weight loss. We have no information on other potential causes but did however exclude women with a history of pre-pregnancy chronic disease. Another limitation is declaration bias due to self-reported data.ConclusionsHealth professionals should be aware that GWG may offset the expected effect of weight loss before conception on fetal growth in overweight and obese women. Further studies are required to understand the underlying mechanisms in order to develop weight-control interventions and improve maternal periconceptional health and developmental conditions for the fetus.

Breastfeeding initiation and duration in France: The importance of intergenerational and previous maternal breastfeeding experiences — results from the nationwide ELFE study

ObjectiveTo assess the role of the mother's mother and mothers' previous personal experiences with breastfeeding and childcare in breastfeeding practices. Design and settingThe analysis included 13,774 mother–infant dyads from the French national birth cohort ELFE. Feeding practices were assessed by face-to-face interview in maternity wards in 2011, by phone interviews at months 2 and 12 post-partum and by Internet/paper questionnaires monthly from months 3–10. Sociodemographic, maternal and newborn-related factors were collected in the maternity unit and by postnatal phone interview at month 2. Multivariable logistic and linear regression was used to assess the association of mother's mother and mothers’ previous personal experiences with breastfeeding initiation and duration. FindingsPrevious breastfeeding experience (i.e., whether mothers had breastfed their previous children) was positively associated with both breastfeeding initiation and duration. Mothers who had been breastfed themselves as infants were more likely to initiate and continue breastfeeding than non-breastfed mothers. Conversely, non-breastfed mothers who had received care advice from their own mother were less likely to start and maintain breastfeeding. The effect of having been breastfed in infancy was especially important for primiparous mothers and to a lesser extent, multiparous mothers with no previous breastfeeding experience. Also, formal experience in childcare, in a professional context, was associated with breastfeeding initiation but not duration. Key conclusions and implications for practiceMother's mother and mother's previous breastfeeding experience have a strong influence on breastfeeding practices. Breastfeeding interventions should be tailored to the mother's level of experience and should provide extra support for multiparous mothers with no previous breastfeeding experience.

Multi-Sources Exposure to Pesticides during Pregnancy and Risk of Hypospadias and Cryptorchidism: The French National Birth Cohort Elfe

Prenatal occupational exposure to pesticides has been associated to male reproductive tract abnormalities. Exposure of the general population might occur through other sources (domestic uses, diet and living proximity to crops) but little is known on the developmental effects of non-occupational exposure. We aimed to assess the association between this multi-sources exposure to pesticides during pregnancy and the risk of hypospadias and cryptorchidism.Among the 9,059 boys of the French birth cohort Elfe, 51 were diagnosed with hypospadias and 134 with cryptorchidism. Exposure was assessed from 1) self-reported domestic uses of 8 pesticide product types, 2) acreage within a 1000m-buffer around home for 11 crops using French spatialized data of soil occupancy and agricultural register, and 3) maternal daily intakes estimated from food-frequency questionnaire and national survey data for 60 pesticide residues in food. For each exposure source, due to high number of variables, best-predictors selection procedure (Elastic Net) was firstly used. We then used logistic regression to assess simultaneously associations for the multiple selected exposure sources, accounting for confounding. Multiple imputation was used to handle for missing data.An increased risk of hypospadias was observed in association with domestic uses against fleas and ticks (OR&amp;#61;1.58, 95% CI: 1.10;2.23), with acreage of barley within the 1000m-buffer around home (1.69, 1.17;1.44), and with dietary intakes of &amp;#955;-cyhalothrin (2.09, 1.11;3.95). For cryptorchidism, an increased risk was associated with the acreage of miscellaneous cereal crops within the 1000m-buffer (1.59, 1.04;2.41). No association was observed with domestic uses nor with dietary exposure.Using population-based cohort, our results suggest a possible increased risk of hypospadias and cryptorchidism in association with prenatal exposure to pesticides from some dietary and residential sources. This work is limited by a modest number of cases.

Factors associated with the introduction of complementary feeding in the French ELFE cohort study.

The objectives of this study were to estimate the age of complementary feeding introduction (CFI) and investigate the related health, demographic, and socio-economic factors. Analyses were based on 10,931 infants from the French national birth cohort ELFE, born in 2011. Health, demographic, and socio-economic data concerning infants and parents were collected at birth (face-to-face interviews and medical records) and 2months (telephone interviews). Data on milk feeding and CFI practices were collected at birth and 2months then monthly from 3 to 10months using online or paper questionnaires. The associations between both health and social factors and CFI age were tested by multivariable multinomial logistic regressions. The mean CFI age was 5.2±1.2months; 26% of the infants started complementary feeding before 4months of age (CF<4months), 62% between 4 and 6months of age, and 12% after 6months of age (CF>6months). CF<4months was more likely when mothers smoked, were overweight/obese, younger (<29years), and used their personal experience as an information source in child caregiving and when both parents were not born in France. CF<4months was less likely when the infant was a girl, second-born, when the mother breastfed longer, and had attended at least one birth preparation class. Mothers of second-born infants and who breastfed their child longer were more likely to introduce CF>6months. Couples in which fathers were born in France and mothers were not born in France were less likely to introduce CF>6months. CF<4months occurred in more than 25% of the cases. It is important to continue promoting clear CFI recommendations, especially in smoking, overweight, young, not born in France, and nonbreastfeeding mothers.

Use of infant formula in the ELFE study: The association with social and health-related factors.

Breastfeeding is recommended until 6months of age, but a wide range of infant formula is available for nonbreastfed or partially breastfed infants. Our aim was to describe infant formula selection and to examine social- and health-related factors associated with this selection. Analyses were based on 13,291 infants from the French national birth cohort Etude Longitudinale Française depuis l'Enfance. Infant diet was assessed at Month 2 by phone interview and monthly from Months 3 to 10 via internet/paper questionnaires. Infant formulas were categorized in 6 groups: extensively or partially hydrolysed, regular with or without prebiotics/probiotics, and thickened with or without prebiotics/probiotics. Associations between type of infant formula used at 2months and family or infant characteristics were assessed by multinomial logistic regressions. At Month 2, 58.1% of formula-fed infants were fed with formula enriched in prebiotics/probiotics, 31.5% with thickened formula, and 1.4% with extensively hydrolysed formula. The proportion of formula-fed infants increased regularly, but the type of infant formula used was fairly stable between 2 and 10months. At Month 2, extensively hydrolysed formulas were more likely to be used in infants with diarrhoea or regurgitation problems. Partially hydrolysed formulas were more often used in families with high income, with a history of allergy, or with infants with regurgitation issues. Thickened formulas were used more with boys, preterm infants, infants with regurgitation issues, or in cases of early maternal return to work. The main factors related to the selection of infant formula were family and infant health-related ones.

Sociodemographic factors and pregnancy outcomes associated with maternal obesity before pregnancy in a French national birth cohort: effect modification of parity

Sociodemographic factors and pregnancy outcomes associated with maternal obesity before pregnancy in a French national birth cohort: effect modification of parity