gms | German Medical Science

Background: Birthweight too small or too large for gestational age is associated with adverse perinatal outcomes. Short and long term studies of childhood development demonstrated impairment in terms of mental health for SGA (small for gestational age) born children. LGA (large for gestational age) children are associated with a higher risk of caesarean section as a mode of birth and have postnatal adaptation problems due to immaturity. We explored the possibility of assessing the consequences of too small or too large birthweight in the health insurance data.

Methods: We used data from the German Pharmacoepidemiological Research Database (GePaRD) consisting of records from four statutory health insurances, including data about 14 million insured persons which is about 17% of the population in Germany. The database covers all regions of Germany and was demonstrated to be representative for the population in Germany in terms of crude birth rate, fertility rate, and percentage of caesarean sections, twin pregnancies and stillbirths. We used hospital delivery date in order to estimate date of birth and expected due date (contained in ambulatory data) to calculate gestational age at delivery. We applied a fetal growth reference (Global Reference) customized to Germany using birthweight in 40 weeks to classify SGA and LGA children.

Results: A total of 196,165 hospital deliveries could be identified for the years 2005-2006 in the database based on the available delivery date. For 84,435 (43%) also expected due date was available. Among those pregnancies, 92% were delivered at term (37-43 weeks). Birthweight data were not provided by one insurance company yet, resulting in 47% of sample with recorded birthweight (when the sample was restricted to the remaining insurance companies, birthweight for 95% of the infants was available). Mean birthweight in 40 weeks of gestation was 3575 g, 12.0% of the newborns with available birthweight were classified as LGA and 8.4% as SGA. Compared to normal weight children, LGA newborns had a nearly equal higher risk of hospital admission right after delivery adjusting for gestational age at birth (Odds ratio 0.96, 95% confidence interval 0.85-1.08). The difference was much more pronounced for SGA newborns (2.17, 95% CI 1.94-2.42).

Discussion: Health insurance data can be used to establish birth cohort including information on gestational age at birth and the birthweight. The data replicate the well known impairment of SGA newborns when compared to normal weight infants irrespectively of gestational age at birth.