Get ready for a growth spurt. In the next few weeks, your baby will double his weight and add inches to his length. Right now he’s 4 1/2 inches long, (head to rump) and 3 1/2 ounces. His legs are much more developed, his head is more erect than it has been, and his eyes have moved closer to the front of his head. His ears are close to their final position, too. The patterning of his scalp has begun, though his locks aren't recognizable yet. He's even started growing toenails. And there's a lot happening inside as well. For example, his heart is now pumping about 25 quarts of blood each day, and this amount will continue to increase as your baby continues to develop.
The top of your uterus is about halfway between your pubic bone and your navel, and the round ligaments that support it are thickening and stretching as it grows. You're probably feeling a whole lot better as you settle into pregnancy, too. Less nausea, fewer mood swings, and glowing skin contribute to an overall sense of well-being.
Your nipples will have become darker, and the areola around the nipple will become larger and darker in color due to the effects of your hormones.
Stretch marks occur as your skin stretches to allow your bump to grow, and due to tears in the collagen in your skin. They generally occur at times of rapid growth in pregnancy. The older you are during pregnancy the more you are likely you are to get stretch marks as your skin becomes less elastic with age.
Soon you'll experience one of the most wonderful moments of pregnancy - feeling your baby move. While some women notice "quickening" as early as 16 weeks, many don't feel their baby move until about 18 weeks or more. (And if this is your first baby, don't be too impatient — you may not be aware of your baby's movements until 20 weeks or so.) The earliest movements may feel like little flutters, gas bubbles, or even like popcorn popping. Over the following weeks they'll grow stronger and you'll be able to feel them much more frequently