Pregnancy symptoms don't appear until hormone levels produced by the growing placenta rise. While the occasional woman misses the signs of pregnancy until she's in labor, others know they're pregnant almost immediately. No pregnancy symptoms occur until the embryo implants in the uterus -- around six days after fertilization and a week before the first missed period -- and many women won't experience any symptoms this early. Within a week or two after a missed period, many women start to notice body changes.
Breast changes are often the first symptoms of pregnancy, especially in women having their first baby. By week 6 of pregnancy -- 2 weeks after the first missed period -- some women experience heaviness in the breasts and tingling in the nipples. Nausea, with or without vomiting, can also occur shortly after the first missed period. Many women notice an increase in urination starting around week 8 of pregnancy.
A Bit Later
Around week 12 of pregnancy, the uterus grows enough that a health-care provider can actually feel the edge of it, at about the level of the pubic bone. Most women don't actually feel their baby move until between week 18 and 22 of pregnancy, with second-time moms recognizing the movements around two weeks earlier than first-timers.