By week 18 of your pregnancy, your baby's crown-to-rump length is 5 to 5.5 inches long. Your baby continues to develop fat layers and weighs 5.25 ounces. Your baby will continue to grow and develop, but the rapid growth will slow down for a little while. At this point of your pregnancy, your uterus is approximately the size of a canteloupe. Although weight gain varies from woman to woman, your total weight gain at this point should be 10 to 13 pounds.
There is still space available in your uterus and your baby will be active for periods at a time. Your baby may sit cross legged or turn somersaults.
Around this time, your baby becomes more sensitive to the outside world and shows her presence through powerful kicks and prods. The bones through which sound is passed to the inner ear have hardened and the parts of the brain that receives and processes nerve signals from the ears are developing. This means that your baby can hear now. You baby will get used to familiar sounds such as your heart beating, familiar voices, blood rushing through the umbilical cord and other daily routine sounds. Your baby will become startled if he hears a loud sound.