As the natural history of respiratory and allergic manifestations is unclear, our ongoing Paris birth cohort study prospectively assesses the onset of these symptoms in early childhood. Data were collected by five questionnaires sent at regular intervals during the first year of life. Partitioning around medoids (PAM) was used to classify infants according to their bronchial obstructive symptoms. A polytomous logistic regression was performed to assess the eventual predictable power of various respiratory events and perinatal factors. Results are given for 2698 infants. Atopic dermatitis occurred in 17.9% of infants. The main respiratory symptoms in infancy were wheeze in the chest (22%), dyspnoea responsible for sleep disturbance (23.7%), nocturnal dry cough (14.5%) and shortness of breath (4.2%). The PAM method identified three groups of infants. Apart from the G0 group of infants mostly asymptomatic, two distinct clinical phenotypes (G1 and G2: 8.7% and 23.5% of total infants respectively) emerged. G2 was defined by severe bronchial obstructive disorders as all cases of dyspnoea with sleep disturbance were included in this group, while all infants assigned in G1 suffered from nocturnal dry cough. G2 group infants had significantly higher rates of respiratory events while a parental history of asthma, symptoms suggestive of rhino-conjunctivitis and birth season clearly differentiated the G1 group. Finally, G1 and G2 group infants should be closely followed up as they are expected to develop allergic and asthmatic phenotypes, possibly in relation to environmental and behavioural risk factors.