Ecology, Evolution and Genetics. Solutions to many of the world's most pressing environmental issues require a basic understanding of nature at the organismal, population and ecosystems level.
Average. On average, women start to show around the fourth month of pregnancy, between weeks 14 and 17. By week 17 the uterus usually has expanded to just an inch and a half below the navel, making the pregnancy more obvious.
With first time mothers, baby bumps start to show around week 12 of their pregnancy, or just as they enter their second trimester. This is the time when the baby rises out of the pelvis. However, this is not a rule. Some mothers get baby bumps sooner, some get them later. Also, some mothers try to disguise their bump.