At 13 weeks pregnant, the baby (fetus) is approximately 7 to 8 centimeters long from crown to rump (head to bottom), which is about the size of a peach or lemon

. The baby weighs roughly between 14 to 25 grams (about half an ounce)

. In inches, this length translates to about 2.9 to 3.1 inches

. At this stage, the baby's bones are starting to form, and movements such as sucking the thumb and moving arms and legs are becoming more deliberate

. The baby's head is proportionally large, about one-third to half the size of the body length

. The intestines have moved into the abdomen from the umbilical cord, and vocal cords are developing

. In summary:

• Length: ~7.4 cm (2.9 inches)
• Weight: ~14 to 25 grams (0.5 to 0.9 ounces)
• Size comparison: about the size of a peach or lemon
• Development: bones forming, active movements, organs developing

This marks the end of the first trimester and the baby is becoming more fully formed and active inside the womb