Table 3.

Summary of papers included: maternal anaemia or micronutrient status

Authors (year)	Location	Study design	n	BI or IPI	BI/IPI categories	Outcomes assessed	Control for confounders	Findings	Quality score (1–3)
Conde‐Agudelo & Belizán (2000)	Latin America, Caribbean	CS	456 889	IPI	≤5; 6–11; 12–17; 18–23; 24–59; ≥60 months	Anaemia, measured during pregnancy	Prenatal care, smoking, marital status, maternal age, education, parity, delivery mode	IPI < 6 months associated with greater risk of anaemia (adjusted RR = 1.3; CI 1.18–1.43) compared with IPI of 18–23 months. No other significant differences	2
Khan et al. (1998)	Pakistan	R‐Coh	278	IPI	Continuous	Hb change from 1st to 2nd pregnancy, measured 48 h after delivery	Maternal age, parity, initial Hb	IPI was not associated with change in Hb between 1st and 2nd pregnancies	1
Pathak et al. (2004)	India	CS	283	IPI	Not stated	Serum Zn, Cu, Mg, ferritin, folate, TSH	Maternal education, parity, dietary intake	IPI not associated with any of the outcomes	2
Singh et al. (1998)	Singapore	CS	3 728	IPI	<3; 3–5; 6–11; 12–17; 18–23 months	Anaemia at delivery	Prenatal care, maternal age, parity, ethnicity, social class, iron supplement, Hb at booking	No association between IPI and anaemia at delivery	3

BI, birth interval; CI, 95% confidence interval; CS, cross‐sectional; Hb, haemoglobin; IPI, interpregnancy interval; R‐Coh, retrospective cohort; RR, relative risk; TSH, thyroid‐stimulating hormone.