Fetal development
From ChildWiki.com
Once pregnancy is installed, various modifications appear in the woman's body throughout the pregnancy, and the fetal development begins.
Until week 10, or 8 weeks from conception, the conception product is called an embryo and from now on he starts to look more and more like a human child. From this point forward, it will be called a fetus. At a gestational age of 10 weeks, the fetus will only weight 10 grams and measure about 3 centimeters(from his head to the end of the spinal cord).
By the end of the first trimester of pregnancy (gestational week 10 to gestational week 12, the organs of the fetus are mainly developed, and now the fetus will start to grow and develop gradually until he reaches the weight he will have at birth.
At first, the fetus has red skin, translucent, but throughout the pregnancy its skin gets thicker and will be covered in vernix(a protective layer of white cholesterol-based fats). The vernix will protect the matured skin from getting wrinkled and will make it impermeable, beacuse the skin is always inside the amniotic liquid. By the end of week 12, the fetus will weight 15 grams and measure 8 centimeters, and the main organs, as the heart, liver, kidneys are already formed and in their spots.
The sex of the baby is recognized starting with week 14, but it will only be observed if the fetal position allows it starting with week 20, in an echography scan.
During the next weeks, the fetus grows and develops rapidly, modifying its body proportions as well. If he reaches the gestational age of 24 weeks the fetus is considered viable, meaning that if is born after this moment he might be able to survive. In reality, birth is very risky at this gestational age for the baby and he has minimal survival changes because his internal organs and tissues are not completely matured yet.
With each week that passes after the 24 weeks step, the changes of survival raise a lot. Because of progresses made in medicine, right now almost all newborns that come to life at a gestational age of 30 weeks survive.
At the beginning of the third trimester of pregnancy (week 28), the fetus weights about 1000 grams and measures almost 25 centimeters, its vital organs are almost completed, the lungs are getting ready to breathe with the help of the umbilical cord.
In the last weeks of pregnancy, when birth approaches, the fetus will weight around 2800-3500 grams and will measure between 48-52 centimeters, depending on sex and genetic factors.Starting with week 38, the pregnancy is considered on term and all internal organs are sufficiently matured to survive the world outside the uterus without assistance. Most babies are born after a gestational age of 40 weeks, but a normal birth can occur at any time between 38 and 42 weeks since conception.
