*3.5. Gender Difference in Object Control Skills*

Thirty-seven articles (thirty-eight studies) assessed proficiency in object control skills [28–57,59–65], including 4291 boys and 4103 girls. Figure 4 displays forest plots of the standardized mean differences and 95% CI for the object control skills score (38 studies) based on the random effects meta-analysis results. Significant differences were found, favoring boys vs. girls (SMD = 0.48 (95% CI 0.38, 0.58), *p* < 0.00001). Meta-regression displays that age is associated with gender differences in object control skills (*p* < 0.05). To further explore the effect of age, we divided studies with age-specific assessments into a 3 year-old group, a 4 year-old group, a 5 year-old group and a 6 year-old group. In subgroup analyses (Figure 5), we found marginally significant results favoring boys vs. girls in children aged 3 (SMD = 0.27 (95% CI 0.00, 0.54), *p* = 0.05) and significant results favoring boys vs. girls aged 4, 5 and 6 years (SMD = 0.58 (95% CI 0.38, 0.77), *p* < 0.00001; SMD = 0.59 (95% CI 0.31, 0.88), *p* < 0.00001; SMD = 0.81 (95% CI 0.61, 1.01), *p* < 0.00001), which increased with age.
