Inclusion and exclusion criteria
The inclusion criteria for this study were singleton pregnancies
resulting in the live birth or stillbirth of phenotypically normal
babies at > 24 weeks’ gestation. Pregnancies with
fetal aneuploidies or major defects diagnosed in the antenatal or
neonatal period and pregnancies ending in miscarriage at <24
week’s gestation were excluded.
For every 5 cases with CH, we selected approximately 1 control from
uncomplicated pregnancies that resulted in the live birth of
phenotypically normal neonates that were matched to the cases for
storage time of maternal serum and racial origin, because the incidence
of chronic hypertension is 3 times higher in Black than white women.