Risk of stillbirth among pregnant women with anaemia in India: secondary analysis of multiple cohorts from the ICMR-SPIC consortium.

BACKGROUND: India contributed to 17.3% of the global stillbirth burden in 2019 and anaemia, an important risk factor for stillbirth, affects nearly half of pregnant women in the country. To understand the relationship between maternal anaemia and stillbirth, we analysed a diverse multicohort dataset from the Stillbirth Pooled Indian Cohort Consortium (ICMR-SPIC) from India. METHODS: This was a secondary analysis of the ICMR-SPIC dataset, which includes individual-level data from eight observational studies and two randomised controlled trials conducted across ten states in India. Most cohorts recruited participants between 2010 and 2023, except for the Pune Maternal Nutrition Study (PMNS), which recruited participants between 1994 and 1996. A total of 214,709 singleton pregnant women with known birth outcomes and haemoglobin measurements during pregnancy were included. Unadjusted and adjusted risk ratios for the association between maternal anaemia and stillbirth were estimated using modified Poisson regression for each cohort and pooled using a random-effects meta-analysis. Kaplan-Meier survival curves were estimated for foetal survival beyond 28 weeks of gestation across categories of anaemia severity. FINDINGS: The median maternal age of the women was 23 years (IQR 21-25). There were 108,982 (52%) women with moderate to severe anaemia (haemoglobin [Hb] <10 g/dL) and 3595 (1.7%) stillbirths. We found that moderate to severe anaemia at any point during pregnancy was associated with a higher risk of stillbirth after 28 weeks of gestation (aRR 1.27, 95% CI 1.07-1.51). The risk ratio for severe anaemia (<7 g/dL) was 3.12 (95% CI 2.46-3.97), and for moderate anaemia it was 1.20 (95% CI 1.02-1.40) at any gestational age, compared to women with no or mild anaemia. We found that stillbirths occurred around the 29th week of gestation among pregnant women with severe anaemia, compared to around 31 weeks of gestation among other women. INTERPRETATION: These findings highlight that maternal anaemia is an important and potentially modifiable risk factor for stillbirth, with severe anaemia associated with early occurrence of stillbirth. Policies aimed at reducing stillbirths should prioritise comprehensive anaemia prevention and treatment strategies among pregnant women. FUNDING: Indian Council of Medical Research.