What is the length of gestation for a baby and how is the age determined?

The gestation period is actually a fancy term to say how long a woman is pregnant and when she is going to have a baby. So, when it comes to human females, this period of pregnancy lasts from 38 to 42 weeks, if there aren't any complications. If a child is born before week 37, then that would be a premature baby. When it comes how the age is determined, well, it starts from the day the baby is born - that is its first day "alive."

Stand or kneel behind the child and wrap your arms around his or her waist. locate the navel with one or two fingers in the middle of the child’s abdomen. just above the navel and well below the lower tip of the breastbone