Objective: Our study evaluates the clinical efficacy of intravenous (i/v) amino acids in the prevention of lactation insufficiency and improvement of neonatal weight gain. Design: A prospective, randomized, open-label, placebo-controlled clinical trial is reported. Population or sample: This study recruited 305 lactating mothers of age-group, 22–35 years. Methods: Test group, n = 152, received i/v amino acid infusion, 500 mL, as study drug once daily for 4 days, and control group, n = 153, received normal saline as placebo, 500 mL od for 4 days. Main outcome measures: We studied the efficacy and safety of i/v amino acids in the prevention of lactation insufficiency. We further evaluated the role of maternal amino acid supplementation in ameliorating physiological weight loss and overall neonatal weight gain. Results: Lactation onset was reported in 86.3% of mothers in the amino acid group at day 0 as compared to 32.23% in the control group (p value < 0.001). Lactation was achieved by all the mothers in the study group by day 1 itself with two doses of i/v amino acids (p value < 0.001). An increase in neonatal weight was observed in the amino acid group, (2.900 ± 0.488, p value = 0.001) compared with the control group at 2 weeks (2.716 ± 0.484, p value = 0.001). Conclusion: Maternal amino acid supplementation is proven to be both efficacious and safe in augmenting breast milk production, thereby preventing lactation insufficiency. It effectively prevented neonatal physiological weight loss at 2 weeks and promoted substantial weight gain over a period of a month after birth.