Study population
This was a prospective screening study for hypertensive disorders in women attending for their routine first hospital visit in pregnancy. This survey for high risk screening protocol was prospective, designed before any of the records analysed in our on-going data collection protocol sought prenatal care. In this visit, which is held at 11+0–13+6 weeks of gestation, all women have an ultrasound scan to confirm gestational age from the measurement of the fetal crown-rump length, to diagnose any major fetal abnormalities and measure fetal nuchal translucency thickness as part of screening for chromosomal abnormalities.13, 14 In this visit, we also record maternal characteristics and medical history and obtain written informed consent to participate in the research study.