The prevalence of childhood obesity, diabetes, metabolic syndrome, and cardiovascular disease is increasing at alarming rates. Recent studies suggest that unfavorable gut microbiota and chronic low-grade inflammation in obese mothers before pregnancy, during gestation and lactation may link to metabolic diseases in offspring. Colonization of gastrointestinal tract starts as early as in utero, which implicates that offspring born form obese mothers have different bacterial population that may be prone to obese in later life.