Interdental Brushing and Obstetrical Outcomes in Nulliparous Pregnant Women: Insights From a Cluster Randomised Controlled Trial

AIM: Pregnancy gingivitis is potentially modifiable, making it a promising target for preventive strategies to reduce adverse obstetrical outcomes. The primary objective of this study was to evaluate whether an interdental hygiene intervention in early pregnancy could reduce obstetrical complications. Exploratory analyses focused on potential biological pathways linking oral inflammation and obstetrical outcomes. MATERIALS AND METHODS: A two-arm randomised controlled trial (RCT) with cluster allocation (1:1) was conducted in six antenatal clinics in Senegal among nulliparous women at 12 weeks. Participants received either a daily calibrated interdental brushing intervention (Intervention) or usual oral hygiene (Control). Follow-up visits were scheduled at 5 and 8 months. The primary endpoint was a composite of preterm birth, low birth weight, small for gestational age or pre-eclampsia, analysed exploratorily under the intention-to-treat principle. RESULTS: A total of 323 women were randomised (162 intervention, 161 control). The composite outcome occurred in 28.4% of the intervention group and 24.2% of the control group (p = 0.449). After adjustment, the intervention was not significantly associated (aOR = 0.65; 95% CI: 0.39-1.10; p = 0.107). Exploratory analyses suggested that interdental bleeding and C-reactive protein (CRP) could act as mediators, accounting for ~60% of the effect, with the remaining ~40% representing a direct effect. No intervention-related adverse events were observed. CONCLUSION: This RCT did not demonstrate a significant reduction in obstetrical complications with early interdental prophylaxis. However, the intervention was safe, acceptable and feasible within antenatal care, highlighting the need for adequately powered trials to clarify its potential clinical impact.