Hospitals across the UK will send study invitation letters and information packs to mothers of infants who are eligible to take part in this study. These study information packs will include paper copies of the consent form and study entry questionnaire. Links to online versions of these forms will also be provided in the information pack. Mothers of eligible infants who would like to take part in the study will be asked to return the completed forms to the University of Bristol using the prepaid addressed return envelope provided in the information pack, or to complete the online versions of these forms if preferred.

                                                                                                  

The study entry questionnaire will ask mothers to provide a contact address (email or postal) or phone number. These details will be used to contact mothers when their child is 18-24 months of age, to invite mothers to complete questionnaires about how their child is developing. These development questionnaires can be filled in online, or if preferred, paper versions of the questionnaire will be posted along with a prepaid addressed return envelope. If translation to a different language is needed, questionnaires can be completed over the phone using translation services. These questionnaires will include the Ages and Stages Questionnaire (ASQ) which is a validated questionnaire used by professionals to monitor a child’s developmental progress. For more information about this questionnaire, please visit: https://agesandstages.com/about-asq/for-parents. We will also ask some information about the child’s medical history and health care usage.