“…In addition, we collected extensive data on maternal living environments and lifestyles during pregnancy, such as fish and meat consumption, leisure time spent in forests, the presence of older siblings or furry pets in the home, smoking in the home and maternal weight, and established that these prenatal factors had little effect on the microbial composition of meconium. It is therefore understandable that the prenatal factors considered in our systematic review, including maternal diet, 2 , 37 , 84 , 85 residential area, 37 , 44 age, 37 , 44 , 49 , 50 , 53 , 57 , 86 ethnicity, 3 , 49 weight, 3 , 38 , 44 , 49 , 53 , 56 , 57 , 75 , 86 smoking, 3 , 37 , 44 , 87 pregnancy-related health issues, 36 – 40 , 47 , 49 , 54 , 60 , 71 , 75 , 85 , 86 non-pregnancy-related health issues 3 , 37 , 38 , 44 , 45 , 49 , 70 , 76 , 88 , 89 and education, 37 , 44 , 49 together with environmental pollutants, particularly metals and microplastics 58 , 90 and the presence of furry pets 13 , 45 yielded mixed results. Another commonly studied newborn factor, which we did not analyze in our cohort study, was gestational age, 3 , 4 ...…”