Fetus
From LoveToKnow Pregnancy
Fetus is the technical term for your unborn child. It takes 40 weeks for your fetus to grow from a cluster of cells to a beautiful newborn baby.
Your Fetus in the First Trimester
The first trimester of pregnancy is defined as the first day of your last period to week 12. During this time, your fetus changes from a tiny lump of cells implanting into your uterus to an identifiably human baby that is three inches long and weighs about half an ounce.
By week 5, your baby’s heart is beating and a very basic circulatory system is in place. You won’t be able to hear your baby’s heart beat, but if you have an ultrasound you can see it beating.
By week 9, your baby is moving. However, you will not be able to feel the kicks for many weeks. By week 10, your baby is producing 250,000 new neurons every minute and by week 11, your baby’s sex may be discernable.
During this trimester, the fetus develops arms and legs. Fingers and toes form with the beginnings of fingernails and toenails. The brain and spinal cord form. Tooth buds, ears, and eyelids form and the groundwork is in place for your baby’s organs.
In the Second Trimester
The second trimester is defined as week 13 through week 26. By the second trimester, exhaustion, morning sickness, and mood swings have stabilized. You will notice your breasts and belly getting larger as your baby grows. In this trimester, you will feel your baby move. This is also called quickening.
Your baby is changing and growing each week. Facial features have formed and ultrasounds have shown the fetus squinting and frowning in this trimester. Your baby may actually be able to put his/her thumb in his/her mouth.
By week 18, your baby can hear! In this trimester and the next trimester your baby will be learning your voice, your partner’s voice, siblings’ voices, and noises like barking dogs or vacuums.
Lanugo or fine body hair grows on your baby’s skin during this trimester. If your baby is premature, you may find a little bit of this hair on his/her shoulders and back.
By week 22, your baby weighs about one pound and his/her taste buds have developed. By week 23, your baby has a chance to survive if he/she is born prematurely.
By the end of this trimester, your baby has fingerprints, footprints, eyebrows, eyelashes, and pinkish skin. Your baby’s eyes are developed, though they won’t open for another few weeks. Your baby weighs between one and a half and two pounds.
In the Third Trimester
The third trimester is week 27 until you deliver. By this trimester, most of your baby’s major organs have formed. If born now, he/she has a high chance of survival.
Your fetus has now developed a sleep cycle that you might notice as a period of less movement. You may also notice jerky movements that indicate your baby has the hiccups.
Vernix coats your baby and helps protect his/her skin from amniotic fluid. At birth, you may notice some of this waxy white substance. It is not harmful and can be rubbed into your baby’s skin.
By week 30, your baby starts gaining half a pound a week until week 37! By week 33 your baby can detect light and your baby’s lungs are almost fully developed. By week 36, your baby can suck. And by week 38, your baby is considered full term, though organ function and growth continues until you deliver.
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