Remember when your child was a baby and you swore they grew overnight ... For adolescents, growth spurts last about a week.

Growth spurts are another common cause of cluster ... their birth weight during the first five days of life. By 2 weeks old, your baby should be back up to their birth weight.

Jessica Simpson's youngest daughter is growing up before her very eyes. Last month, the "I Think I'm In Love With You" singer, who is in the midst of her musical comeback, celebrated her daughter ...