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.
Pathogenic bacteria are bacteria which are capable of causing disease. Humans are generally most interested in the species of bacteria which can cause disease in humans, although these bacteria can also infect other animals and plants. Some notable pathogenic bacteria include Streptococcus, Staphylococcus, Tuberculosis, and Escherichia coli, among many others.