Clinical prediction in early pregnancy of infants small for gestational age by customised birthweight centiles: findings from a healthy nulliparous cohort.

Abstract

Small for gestational age (SGA) infants comprise up to 50% of all stillbirths and a minority are detected before birth. We aimed to develop and validate early pregnancy predictive models for SGA infants.5628 participants from SCOPE, a prospective study of nulliparous pregnant women, were interviewed at 15 ± 1 weeks' gestation. Fetal anthropometry, uterine and umbilical Doppler studies were performed at 20 ± 1 weeks'. The cohort was divided into training (n = 3735) and validation datasets (n = 1871). All-SGA (birthweight 12 months to conceive, university student, cigarette smoking, proteinuria, daily vigorous exercise and diastolic blood pressure ≥ 80. Recreational walking ≥ 4 times weekly, rhesus negative blood group and increasing random glucose were protective. AUC for clinical risk factors was 0.63. Fetal abdominal or head circumference z scores <10(th) centile and increasing uterine artery Doppler resistance at 20 ± 1 weeks' were associated with increased risk. Addition of these parameters increased the AUC to 0.69. Clinical predictors of Normotensive and Hypertensive-SGA were sub-groups of All-SGA predictors and were quite different. The combined clinical and ultrasound AUC for Normotensive and Hypertensive-SGA were 0.69 and 0.82 respectively.Predictors for SGA of relevance to clinical practice were identified. The identity and predictive potential differed in normotensive women and those who developed hypertension.