Early lung function deficits represent a significant risk factor for the evolution toward chronic obstructive pulmonary disease later in life. Prematurity and in utero tobacco smoke exposure are already known to predispose children to develop a non-reversible obstructive ventilatory defect in adulthood. The role of vitamin D status during pregnancy is less certain. In humans, low vitamin D concentrations during pregnancy are associated to an increased risk of asthma in children. In murine models, low vitamin D concentrations during pregnancy are associated to structural abnormalities of the airways in mouse pups. Investigators hypothesized that vitamin D play a role in early airways development, from the first trimester of pregnancy. To bring arguments to this hypothesis, the investigators will study the association of airway resistance in children aged 5 to 6 years old with the concentration of vitamin D during the first trimester of pregnancy in their mothers.

Children aged 5 to 6 years old will be included from the FEPED cohort. The FEPED cohort is a cohort of French pregnant women designed to study the association between vitamin D status during pregnancy and the risk of pre-eclampsia. Vitamin D concentration at first and third trimester of pregnancy as well as in cord blood is available for 1400 women. Investigators will include 200 children born from these women. Children will undergo lung function tests and prick-tests and parents will answer the ISAAC questionnaire that is a standardised questionnaire designed to evaluate asthma and rhinitis symptoms. The main outcome of this study will be specific airway resistance. The investigators will look for an association between specific airway resistance and vitamin D concentration measured during the first trimester of pregnancy in their mothers.

Inclusion Criteria:

• term-born child (gestational age ≥ 37 weeks of post-menstrual age) whose mother was included in the FEPED cohort
• measure of vitamin D concentration available at the first and third trimester of pregnancy and in cord blood
• cord blood sample available for DNA extraction
• child's age between 5 and 6 years old at the time of participation
• written informed consent obtained from the legal guardian of the child
• health insurance

Exclusion Criteria:

• parent's' refusal
• underlying disease that does not allow the performance of lung function tests

term-born child (gestational age ≥ 37 weeks of post-menstrual age) whose mother was included in the FEPED cohort, with measure of vitamin D concentration available at the first and third trimester of pregnancy and in cord blood