OC02.08: *Effect of Mediterranean diet or stress reduction interventions during pregnancy on placental volume and perfusion: IMPACT BCN trial sub‐analysis

To investigate the effect of Mediterranean diet (MedDiet) or mindfulness-based stress reduction (MBSR) during pregnancy on placental volume and perfusion in high-risk pregnancies from the IMPACT BCN trial. In the IMPACT BCN trial, a parallel group randomised clinical trial conducted at a University Hospital in Barcelona, Spain (2017-2020), 1221 pregnant women at high-risk for small for gestational age (SGA) were randomly allocated at 19-23 weeks' gestation into three groups: MedDiet, MBSR or usual care. Participants in the MedDiet group received monthly individual and group educational sessions, and free provision of extra-virgin olive oil and walnuts. Women in the MBSR group underwent an 8-week MBSR adapted for pregnancy. Placental volume and perfusion were assessed in a subgroup of randomly selected pregnant women (n = 165) from the three study groups using magnetic resonance (MR) imaging at 36 weeks' gestation. Small placental volume was defined as MR estimated volume <10th centile. Perfusion was assessed by MR Intravoxel incoherent motion (IVIM). While mean MR placental volume was similar among the study groups, both interventions were associated with a lower prevalence of small placental volume compared to usual care (3.9% in MedDiet and 5% in MBSR vs. 17% in usual care; p = 0.03 and p = 0.04 respectively). Logistic regression showed that small placental volume was significantly associated with higher risk of SGA in both study groups (odds ratio (OR) 7.48 (95% confidence interval 1.99–28.09), p = 0.003 in MedDiet; and OR 20.44 (5.13-81.4), p < 0.001 in MBSR. Results of placental IVIM perfusion fraction and diffusion coefficient were similar among the study groups. Structured interventions during pregnancy based on MedDiet or MBSR are associated with a lower proportion of small placentas, which is in line with the main outcome of the trial, that showed beneficial effects of these interventions on fetal growth.