Women with moderate anaemia prior to conception benefited most from nutrition interventions: a secondary analysis of the Women First preconception maternal nutrition trial

INTRODUCTION: The Women First (WF) Preconception Maternal Nutrition trial found greater benefits of small-quantity lipid-based nutrient supplements (SQ-LNS) for intrauterine growth among anaemic versus non-anaemic women at preconception. We investigated whether the benefits of SQ-LNS in improving markers of intrauterine growth occurred evenly across the mild to moderate spectrum of pre-pregnancy anaemia. METHODS: We analysed WF data (n=2443 maternal-newborn dyads) from Pakistan, India, Guatemala and the Democratic Republic of Congo. Women received SQ-LNS either ≥3 months preconception through pregnancy (Arm 1); starting in the late first trimester (Arm 2); or not at all (Arm 3: control), with all supplementations discontinued at delivery. The outcomes were infant weight, length and head circumference measured within 48 hours of birth, expressed as Z-scores. For each site, adjusted mean differences in the Z-scores were computed across six pre-pregnancy haemoglobin (Hb) categories (80-89, 90-99, 100-109, 110-119, 120-129, and ≥130 g/L) and pooled using meta-analysis. RESULTS: The effect of SQ-LNS on birth weight, length and head circumference varied by pre-pregnancy Hb categories. No significant differences in pooled mean Z-scores were observed for any Hb category >110 g/L, and no differences were found for Arm 1 vs Arm 2 across any Hb categories. For women with Hb 90-99 g/L pooled mean differences (95% CI) in the Z-scores for length (0.60 (0.03 to 1.23)), weight (0.50 (0.11 to 0.89)) and head circumference (0.26 (0.02 to 0.51)) were greatest for Arm 1 versus Arm 3. For women with Hb 100-109 g/L in Arm 1 versus Arm 3, pooled mean difference (95% CI) in birth weight Z-scores was significantly greater (0.33 (0.24 to 0.42)). Arm 2 vs Arm 3 women with Hb 90-99 g/L had greater birth weight Z-scores (0.14 (0.05 to 0.22)). CONCLUSION: The findings highlight the importance of identifying women preconception for whom nutrition interventions may have the greatest impact on fetal growth.