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.
Probiotics. Probiotics contain various strains of bacteria that are similar to the natural healthy gut flora of the body. They are available at many health food stores as supplements, but are also added to some dairy products, such as yogurt. The most common species found are Lactobacillus acidophilus and Bifidobacterium bifidus. It is important to note that probiotics are live microgranisms and not the same as prebiotics, which stimulate growth of the probiotic bacteria.