Pharmacological interventions for the prevention of fetal growth restriction: a systematic review and network meta-analysis

The prevention of fetal growth restriction (FGR) is challenging in clinical practice. To date, no meta-analysis summarized evidence on the relative benefits and harms of pharmacological interventions for FGR prevention. We performed a systematic review and network meta-analysis (NetMA), searching PubMed, Embase, Cochrane Library and ClinicalTrials.gov from inception until November 2019. We included clinical trials and observational studies on singleton gestating women evaluating antiplatelet, anticoagulant, or other treatments, compared between each other or to control (placebo or no treatment), and considering the pregnancy outcome FGR (primary outcome of the NetMA). Secondary efficacy outcomes included preterm birth, placental abruption, and fetal or neonatal death. Safety outcomes included bleeding and thrombocytopenia. Network meta-analyses using a frequentist framework were conducted to derive odds ratios (OR) and 95% confidence intervals (CIs). Out of 18780 citations, we included 30 studies on 4326 patients. Low molecular weight heparin (LMWH), alone or associated with low-dose aspirin (LDA), appeared more efficacious than control in preventing FGR [OR 2.00 (1.27 - 3.16) and 2.67 (1.21 - 5.89) for control vs LMWH and LDA+LMWH, respectively]. No difference between active treatments emerged in terms of FGR prevention, but estimates for treatments other than LMWH+/- LDA were imprecise. Only the confidence in the evidence regarding LMWH vs control was judged as moderate, according to the CINeMA framework. No treatment was associated with an increased risk of bleeding, although estimates were precise enough only for LMWH. These results should inform clinicians on the benefits of active pharmacological prophylaxis for FGR prevention.