Background: Gastrointestinal symptoms are common during infancy and are a key component of clinical assessments in infant trials. This systematic review and meta-analysis aims to explore the factors influencing parental reporting of gastrointestinal symptoms and the typical gastrointestinal profile of breastfed infants. Methods: Studies using the Infant Gastrointestinal Symptom Questionnaire (IGSQ) to examine gastrointestinal symptoms among healthy breastfed infants aged <12 months. PubMed, Embase, Google Scholar were searched up to February 2026. The endpoint was IGSQ scores, by age and geography. Meta-analyses were conducted using random effects models. The meta-analysis was registered on PROSPERO (CRD42024596049). Results: Among 128 publications screened, 14 reported aggregate IGSQ data (Europe, n=7; Asia, n=6; US, n=l) involving1677 breastfed infants. Age at IGSQ assessment ranged from 0-12 months. Meta-analyzed mean [95% CI] IGSQ scores by age group were 17.95 [15.88, 20.01] for infants <1 month, 19.12 (17.03, 21.22] for those aged 1-3 months, and 18.24 [15.41, 21.08] for infants aged 4+ months(p=0.72). Analysis of mean IGSQ scores by age and geography revealed a significant difference (p<0.05) between Asia and Europe during the 1st month of life (16.30 versus 20.49), in the 1-3-month group (16.58 versus 21.05), and in the 4-month+ group(14.25 versus 20.28). Conclusion: Parental reporting of gastrointestinal symptoms in healthy breastfed infants varies across geographies and age groups. A planned pooled individual participant data analysis will examine how socio-demographic factors–such as country, parental age, education and employment, delivery mode, presence of siblings, daycare attendance and smoking–influence this variability. The pooled individual participant data analysis aims to establish reference gastrointestinal symptom profiles and scores for breastfed infants across age groups and regions. This work will provide a benchmark to aid in the interpretation of future studies.