The FACILITY STUDY is aimed at evaluating maternal and children social, cultural, economic and lifestyle-related risk factors for the development of childhood overweight, obesity and early adiposity rebound (EAR). This study consists of two phases: a cross-sectional phase and a retrospective case-control study.

The FACILITY retrospective case-control study is conducted in one Italian hospital in Milan (Buzzi Children's Hospital) on children and adolescents (2-18 years old) with EAR and their mothers (≥ 18 years old). The estimated duration is 24 months.

The primary objective of the FACILITY retrospective case-control phase is to identify maternal and child lifestyle and health determinants of EAR associated with childhood obesity. The secondary objective is to identify culture-accepted early-tailored-efficiency "model to action" aligned with the Maternal, New-born, and Child Health (MNCH) continuum care approach. This "policy-model" will be based on the results of the retrospective study and on the analysis of the current scientific evidence and on the research of the global, national and local policies (city of Milan).

Participants of this study are mother-child dyads previously enrolled in the FACILITY cross-sectional study and willing to participate in the retrospective phase or newly enrolled patients from the hospital according to the eligible criteria. If eligible, variables related to the mothers and to the children will be retrospectively investigated with structured interviews and/or by consulting medical records.

For the mothers, anthropometric variables (height and weight during and after pregnancy) will be obtained from medical records, if available, or will be requested orally by structured interviews. In addition, pathological anamnesis and drug consumption during pregnancy will be evaluated with the same methodologies. Information related to pregnancy, supplements consumption during pregnancy, as well as dietary, smoking, and alcohol habits during pregnancy and breastfeeding will be assessed with structured interviews.

For the child, the nutritional status during the first 1000 days will be evaluated with the pediatric health booklet (weight, height/length, and head circumference). The type of breastfeeding and weaning characteristics will be investigated through a structured interview with the mothers. The child's dietary habits, physical activity, and motor gross achievement will be explored with the same methodologies.

Inclusion criteria (CASE GROUP)

For mothers:

• Age ≥ 18 years old;
• Admitted to the Department of Pediatrics, Buzzi Children's Hospital, Milan, Italy;
• Written and signed informed consent.

For the children/adolescent:

• Age > 2 years and < 18 years old;
• Early adiposity rebound (< 5 years of age);
• Overweight (between 2-3 Z-score) and obesity (≥ 3 Z-score) diagnosis according to the CDC growth charts.
• Admitted to the Department of Pediatrics, Buzzi Children's Hospital, Milan, Italy;
• Mother and father/legal guardian had written and signed informed consent.

Inclusion criteria (CONTROL GROUP)

For mothers:

• Age ≥ 18 years old;
• Admitted to the Department of Pediatrics, Buzzi Children's Hospital, Milan, Italy;
• Written and signed informed consent.

For the children/adolescent:

• Age > 2 years and < 18 years old;
• Early adiposity rebound (< 5 years of age);
• Admitted to the Department of Pediatrics, Buzzi Children's Hospital, Milan, Italy;
• Mother and father/legal guardian had written and signed informed consent.

Exclusion criteria (CASE GROUP and CONTROL GROUP)

For the mothers:

• Mother had not written and signed informed consent;
• Inability to understand the Italian and English language.

For the children/adolescent:

• Endocrine disorders (hypothyroidism, hypercortisolism, growth hormone deficiency);
• Central nervous system damage (hypothalamic-pituitary damage because of surgery or trauma);
• Genetic diseases either monogenic (leptin deficiency, MC4R mutation) or pleiotropic genetic syndromes (Prader-Willi, Bardet-Biedl);
• Mother and father/legal guardian had not written and signed informed consent.

The retrospective study population will be a subgroup of the population previously enrolled during the cross-sectional study according to the previously identified eligibility criteria, specifically: mother-child dyads with overweight or obesity and early adiposity rebound (case) and mother-child dyads with healthy weight (control) will be enrolled. The control group will be matched to the cases selected on the basis of various factors (e.g., age, sex, race) to ensure to reduce confounding factors. New subjects will be enrolled according to the eligibility criteria of the retrospective study if the simple size is not reached.