A Study of Females With CF Throughout Pregnancy and Post-partum, and Follow up of Their Offspring

Inclusion Criteria: 'Mama' sub-study: * Written informed consent obtained from participant. * Under the care of Royal Brompton Hospital CF Reproductive and Maternal Health Service * Age 16 years or above at time of recruitment * Confirmed diagnosis of CF * Planning a pregnancy or pregnant at time of recruitment. * Ability to adhere to the required visits and investigations. 'Mini' sub-study: * Written informed consent obtained from participant's legal guardian. * Infants who have one biological parent with a confirmed diagnosis of CF under care of Royal Brompton Hospital Adult CF Service * Less than 12 months of age at first visit. * Ability to adhere to the required visits and investigations. 'Midi' sub-study: * Written informed consent obtained from participant's legal guardian. * Children who have one biological parent with a confirmed diagnosis of CF who is under the care of Royal Brompton Hospital Adult CF Service. * Age three to six years at time of visit * Ability to adhere to the required visits and investigations. Exclusion Criteria: 'Mama' sub-study: * Any significant health condition which would cause inability to comply with protocol based on investigator discretion. * History of lung transplantation 'Mini' sub-study: * Legal guardians' inability to provide consent to participate in the study. * Mother of infant has significant comorbidities unrelated to CF which could affect infant outcomes based on investigator discretion. 'Midi' sub-study: * Legal guardians' inability to provide consent to participate in the study. * A significant health condition which is known to affect lung function or imaging based on investigator discretion