The data includes prenatal care, delivery care and neonatal care. By linkage to registers provided by Statistics Sweden information on personal identification number for the infant, the parents’ nationality and the mother’s country of birth are added to the register.

Records for a small percentage of all infants – 1–5 percent per year – are missing completely. In others cases information may be incomplete due to for example missing data from antenatal-care clinics and paediatric wards. Even though the basic structure of the register has remained unchanged during the years, there have been modifications to content and methods of data collection. More detailed information on the quality of the register (then the Swedish Medical Birth Register) was published in 2003 (The Swedish Medical Birth Register – A Summary of Content and Quality).

By linkage to registers provided by Statistics Sweden information on personal identification number for the infant, the parents’ nationality and the mother’s country of birth are added to the register.

Information from the prenatal care:

• Data on the mother (e.g. personal identification number, age)
• Smoking and snuffing habits (before and during pregnancy)
• Information on previous pregnancies 
• Maternal medical drug use during pregnancy
• Diagnoses before pregnancy

Information from the delivery care

• Maternal diagnoses
• Mode of delivery
• Foetal presentation
• Analgesia and anaesthesia
• Hospital code

Information from the neonatal care 

• The infant's birth weight, body length and head circumference
• Single or multiple birth
• Apgar score
• Infant diagnoses
• Live birth/stillbirth