Comparison 1. Rigid versus squeezable bottle.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Weight (kg)	2		Mean Difference (IV, Fixed, 95% CI)	Subtotals only
1.1 Up to 2 months	1	101	Mean Difference (IV, Fixed, 95% CI)	‐0.05 [‐0.25, 0.15]
1.2 >2 months to 6 months	2	131	Mean Difference (IV, Fixed, 95% CI)	‐0.10 [‐0.42, 0.23]
1.3 >6 months	2	130	Mean Difference (IV, Fixed, 95% CI)	‐0.15 [‐0.53, 0.22]
2 Length (cm)	2		Mean Difference (IV, Fixed, 95% CI)	Subtotals only
2.1 Up to 2 months	1	101	Mean Difference (IV, Fixed, 95% CI)	0.0 [‐0.84, 0.84]
2.2 >2 months to 6 months	2	131	Mean Difference (IV, Fixed, 95% CI)	0.20 [‐0.59, 0.98]
2.3 >6 months	2	130	Mean Difference (IV, Fixed, 95% CI)	0.21 [‐0.72, 1.14]
3 Head circumference (cm)	2		Mean Difference (IV, Fixed, 95% CI)	Subtotals only
3.1 Up to 2 months	1	101	Mean Difference (IV, Fixed, 95% CI)	‐0.40 [‐0.99, 0.19]
3.2 >2 months to 6 months	2	131	Mean Difference (IV, Fixed, 95% CI)	‐0.28 [‐0.70, 0.14]
3.3 >6 months	2	130	Mean Difference (IV, Fixed, 95% CI)	‐0.66 [‐1.16, ‐0.17]