Data sources
The Swedish Pregnancy Register (www.graviditetsregistret.se) is a national quality register, established in 2013. It receives data from multiple sources. A majority of variables are directly transferred from the electronic medical records (EMR). The register contains detailed information of the pregnancies, prospectively entered prospectively into the EMR by midwives and physicians in a standardized manner, starting with the first antenatal visit, and thereafter subsequently at every subsequent visit, including ultrasound examinations, delivery and postnatal care visits. Additionally, the register includes diagnoses and procedure codes for both mothers and infants, coded using the International classifications of disease (ICD) system (with version 10 in use since 1997). Information on clinical characteristics (symptoms and clinical findings such as maternal and fetal heart rate pattern), and laboratory measurements (CRP, leukocyte count and cultures) were extracted manually from medical records by the main author (PB).