Because the prevalence of screening for GDM and HDOP during pregnancy has changed over the period of the births
in this cohort (1964–2001), we repeated the analysis among first births occurring after the baseline 1989
questionnaire, because after that time period, screening was more widely practiced as standard care and gestational
age-dating of pregnancies had probably improved with the advent of ultrasound. The hazard ratios estimated by the
fully adjusted models (including GDM and HDOP diagnoses) were stronger for birth weight and T2DM, which
mitigated the concern that macrosomia in the earlier pregnancies might merely be a marker for undiagnosed GDM.
However, the association of very preterm delivery with T2DM was no longer detectable when limiting the analysis to
pregnancies occurring after 1989.