Fetal Development: Week 18
18 weeks after conception (about 4 ½ months)
(20 weeks after the last menstrual period)
The fetus is about 6 ½ inches (6.5 inches) long from crown to rump (head to butt), about the length of an ear of corn, and weighs about 10 ounces. The skin is thin and nearly see-through because of the lack of fat under the skin. The sex of the fetus can now often be known by ultrasound. Most women feel the fetus moving or kicking, which is called quickening.
A long ear of corn measures 6 ¾ - 7 ½ inches long.