After spending approximately 40 weeks inside the womb, the average newborn weighs 7 1/2 pounds. Most babies weigh between 5 1/2 and 10 pounds. The average length of a newborn is 20 inches (50 centimeters), with a range of 18 to 22 inches. The average head circumference (the distance around the head) is 14 inches (35 centimeters).
Lactobacillus and Bifidobacterium are the most common probiotic bacteria. The Lactobacillus genus has 18 different bacteria strains, while the Bifidobacterium genus consists of eight strains.
Proteobacteria are a major phylum of bacteria (over 32% of all known bacteria), have a great diversity and they are all Gram negative. Many are pathogenic (ie. Escherichia, Helicobacter, Salmonella). They are grouped into six classes: alpha (alphaproteobacteria), beta, delta, gamma, epsilon and zeta. Non-protobacteria are also Gram negative.