Background: Maternal micronutrient deficiencies (MNDs) and inflammation contribute to adverse birth outcomes While the individual effects of MNDs have been studied, the consequence of co-occurring MNDs remains unclear. Objectives: To examine the associations between maternal micronutrient deficiencies and inflammation with adverse birth outcomes (ABOs). Methods: Data from 5,408 pregnant women across 11 datasets from 10 countries were analyzed. Descriptive analyses explored the distribution of MNDs (iron, vitamin A, zinc, serum folate, vitamin D, and vitamin B12) and inflammation (c-reactive protein >5 mg/L or -(1)-acid glycoprotein > 1g/L) by maternal characteristics (age, height, education, socioeconomic status [SES]) using chi-square tests. Associations of 1) single MNDs and inflammation and 2) co-occurring MNDs (2 deficiencies at a time) with low birth weight (LBW, < 2500 g), preterm birth (PTB, < 37 wks), and small-for-gestational age (SGA, < 10th percentile for gestational age), were examined using modified Poisson regression to estimate relative risk (RR), adjusting for age, SES, and dataset. Results: Young maternal age and short height were associated with up to 9.7% and 25% higher prevalence of MNDs and inflammation, respectively. Lower education and SES level were associated with higher prevalence of Vitamin B12 deficiency. Women with folate deficiency had an increased risk of LBW (RR [95% CI]: 1.22 [1.06, 1.39]). Co-occurring MNDs for folate and vitamin B12 were also associated with increased LBW risk (1.38 [1,1.9]) as was folate deficiency without iron (1.28 [1.09, 1.51]) or vitamin B12 deficiency (1.67 [1.09, 2.56]) compared with mothers without either deficiency. Iron deficiency without vitamin B12 deficiency was associated with a reduced LBW risk (0.4 [0.2, 0.79]). Conclusion: Maternal MNDs, especially folate and vitamin B12, are linked to adverse birth outcomes. Complex nutrient interactions highlight the need to explore these relationships to improve maternal and neonatal health interventions.