Objective The evidence for an association between superimposed fetal growth restriction (FGR) and a more severe pre-eclampsia (PE) phenotype is controversial. We investigated whether the presence of FGR in women with early-onset PE was associated with more severe maternal disease compared to those with appropriately grown fetuses (AGA).

Methods This was a retrospective cohort study of women with early-onset PE (PE requiring delivery before 34 weeks) between 2002-2010 at University College London Hospital. Maternal, fetal and neonatal data were collected and study groups compared using X2-test or Fisher's exact test (categorical variables), and Mann Whitney-U test (continuous variables).

Results In women with early-onset PE (n=134), FGR (n=66, 49%) was associated with significantly higher perinatal mortality (p=0.02). Gestational age at delivery was significantly lower in the FGR group (median, IQR: 29.0 weeks, 28.0-32.8 vs 32.0, 30.0-33.2, p=0.01). However, maternal indicators of PE severity, including blood pressure ≥160mmHg systolic or ≥110mmHg diastolic, ALT>100U/L, platelets <100×10⁹/L, use of magnesium sulphate, use of antihypertensive therapy, were similar in the two groups.

Conclusion In women with early onset PE, FGR was associated with worse perinatal outcome, but was not associated with a more severe maternal PE phenotype. This may be because the presence of FGR in these women leads to earlier iatrogenic delivery, before the maternal condition deteriorates, but further studies are needed to investigate this.