Study design and population
This was a retrospective observational study of all pregnant women who
booked for antenatal care and delivery at University College London
Hospital NHS Foundation, UK, between March 2019 and December 2022. The
inclusion criteria for this study were singleton pregnancies resulting
in the livebirth or stillbirth of an infant without any serious
congenital anomalies at ≥ 24 weeks gestation. We excluded patients who
declined first trimester combined screening testing (CST) for trisomy
21, 13 and 18, since PAPP-A results were not available for this cohort.
We also excluded those who did not have a BP recorded from their booking
visit and those who were lost to follow-up. Data on maternal
characteristics and pregnancy outcomes were collected from the hospital
maternity records. Gestational age was determined by crown–rump length
(CRL) measurement performed at the 1st trimester scan
between 11+2 to 14+1weeks.
Standard care, using the NICE guidance, identified women at their
booking midwifery or Obstetric appointment as high risk of developing PE
if they had any one major factor (hypertensive disease in previous
pregnancy, chronic kidney disease, autoimmune disease, diabetes mellitus
or chronic hypertension) or any two moderate factors (first pregnancy at
age ≥ 40 years, interpregnancy interval > 10 years, body
mass index at first visit ≥ 35 kg/m2 or family history
of PE). The current recommendation by NICE is that all women who screen
positive by this method should be offered aspirin prophylaxis of 150mg
until 36 weeks’ gestation. Subsequent pregnancy management including the
need for third trimester fetal growth surveillance or need for earlier
induction of labour was scheduled as recommended by
NICE.12 Maternal serum PAPP-A was measured in those
who consented to CST. Only those with MAP taken according to
standardised protocols by midwives or healthcare assistants were
included in the study.
PE was defined according to the International Society for the Study of
Hypertension (2014) guidelines by having, in addition to hypertension,
at least 1 of the following problems: renal involvement (proteinuria 300
mg/24 h and/or creatinine 90 mmol/L or 1 mg/dL), liver impairment
(transaminases >70 IU/L), neurologic complications (e.g.
eclampsia), thrombocytopenia (platelet count <150,000/mL),
uteroplacental dysfunction (e.g. fetal growth
restriction).13 In addition, according to gestational
age at diagnosis, PE was subdivided into preterm PE with onset at
<37 weeks’ of gestation and term PE with onset beyond 37
weeks. SGA was defined as birthweight <5thpercentile for gestational age.14