This study aims to determine whether breastfeeding duration affects the prevalence of nonrighthandedness in later life. A systematic search for studies on this topic was completed in 2018, and risk of bias was assessed by means of the Newcastle-Ottawa scale. Seven national surveys in five countries with Individual Participant Data (IPD) were identified (n = 62,129 mother-child dyads). These surveys had low risk of bias. An IPD meta-analysis showed that breastfeeding for < 1 month, 1 to 6 months, and > 6 months, when compared to bottle feeding, was associated with a 9%, 15% and 22% decreased prevalence of nonrighthandedness, respectively (Prevalence Ratio (PR) = 0.91, 95% confidence interval (ci): 0.83, 1.00; p-value = 0.05, PR = 0.85, 95% CI: 0.79, 0.92; p-value < 0.0001 and PR = 0.78; 95% CI: 0.71, 0.85; p-value < 0.0001). This dose-response relationship was significant (p < 0.001). No significant heterogeneity across surveys was detected (p-value > 0.54). Breastfeeding for longer than 9 months was not associated with further reductions in the prevalence for nonrighthandedness (p > 0.58). It is concluded that the critical age window for establishing hemispheric dominance in handedness includes the first 9 months of infancy and is in part determined by nurture.

这项研究旨在确定母乳喂养时间是否会影响以后生活中非惯用右手的患病率。在2018年完成了对该主题研究的系统搜索，并通过纽卡斯尔-渥太华量表评估了偏倚风险。在五个国家中进行了七次具有个人参与数据（IPD）的国家调查（n  = 62,129个母子二元组）。这些调查的偏见风险低。IPD荟萃分析显示，与奶瓶喂养相比，母乳喂养<1个月，1到6个月和> 6个月与非惯常使用权的患病率分别降低了9％，15％和22％（患病率（PR）= 0.91，95％置信区间（ci）：0.83，1.00; p值= 0.05，PR = 0.85，95％CI：0.79，0.92; p值<0.0001且PR = 0.78; 95％CI：0.71、0.85；p值<0.0001）。这种剂量反应关系很显着（p  <0.001）。在所有调查中均未检测到明显的异质性（p值> 0.54）。母乳喂养时间超过9个月与非右撇子患病率的进一步降低无关（p  > 0.58）。结论是，建立半球优势的关键年龄窗口包括婴儿期的前9个月，部分取决于培养。