Title: Fetal Period | The final stage of fetal development
Headings: Fetal Period
Fetal Period
The final stage of fetal development
Weeks 10 to 12
Weeks 13 to 16
Weeks 17 to 20
Weeks 21 to 25
Weeks 26 to 28
Weeks 29 to 36
Weeks 37 to 40

Content: Meconium, a thick, dark green waste substance, is produced in the fetus' bowels and remains there (in most cases) until after birth. Weeks 17 to 20
Week 17 to week 20 is a period of rapid growth for the fetus. It begins to accumulate a layer of fat underneath its skin and starts to progress through somewhat regular intervals of wakefulness and sleep. Increased fetal movement is likely to become apparent, in the form of a fluttering sensation in the mother's abdomen. During this period, the sex of the baby can be discovered via ultrasonography. Weeks 21 to 25
Between weeks 21and 25, the fetus becomes covered in lanugo. Eyelashes and fingernails begin to develop. Around this time, doctors are first able to hear the fetal heartbeat using a stethoscope. Movement continues to increase and the fetus develops a startle reflex. Weeks 26 to 28
From week 26 to 28, the lungs are rapidly developing as the fetus readies for its first breath of air.