Raille Thompson, John Thompson, Jessica Wilson, Robin Cronin, Ed Mitchell, Camille Raynes-Greenow, Minglan Li, Tomasina Stacey, Alex Heazell, Louise O'Brien, Lesley McCowan, Ngaire Anderson
OBJECTIVE
Identify independent and novel risk-factors for late-preterm (28-36 weeks) and term (≥37 weeks) stillbirth and explore development of a risk-prediction model.
DESIGN
Secondary analysis of an Individual Participant Data (IPD) meta-analysis investigating modifiable stillbirth risk-factors.
SETTING
An IPD database from five case-control studies in New Zealand, Australia, the United Kingdom and International.
POPULATION
Women with late-stillbirth (cases, n=851), and ongoing singleton pregnancies from 28 weeks’ gestation (controls, n=2257).
METHODS
Established and novel risk-factors for late-preterm and term stillbirth underwent univariable and multivariable logistic regression modelling with multiple sensitivity analyses. Variables included maternal age, BMI, parity, mental health, cigarette smoking, second-hand smoking, antenatal-care utilisation, and detailed fetal movement and sleep variables.
MAIN OUTCOME MEASURES
Independent risk-factors with adjusted odds ratios (aOR) for late-preterm and term stillbirth.
RESULTS
After model building 575 late-stillbirth cases and 1541 controls from three contributing case-control studies were included. Risk-factor estimates from separate multivariable models of late-preterm and term stillbirth were compared. As these were similar the final model combined all late-stillbirths. The single multivariable model confirmed established demographic risk factors, but additionally showed that fetal movement changes had both increased (decreased frequency) and reduced (hiccups, increasing strength, frequency or vigorous fetal movements) aOR of stillbirth. Poor antenatal-care utilisation increased risk while more-than-adequate care was protective. The area-under-the-curve was 0.84 (95% CI 0.82-0.86).
CONCLUSIONS
Similarities in risk-factors for late-preterm and term stillbirth suggest the same approach for risk-assessment can be applied. Detailed fetal movement assessment and inclusion of antenatal-care utilisation could be valuable in late-stillbirth risk-assessment.