What happens to your body and your baby's development during pregnancy? The second trimester of this great experience is called the middle part; many women enjoy this period while their body adjusts to the process; the fetus is not yet so big to make them uncomfortable and morning sickness may subside.

Ultrasound examinations are generally made at the same period, after around 18-20 weeks, in order to check if the fetus is developing well, and identify the gender - in case of wish. It is also at this time that the mother starts feeling her baby move (the baby moves almost all the time throughout pregnancy but mom won't begin to feel it until the 20th week); a sensation that may be subtle at first, before feeling definite kicks and rolls from the baby.

The blood volume of pregnant women increases by 30 to 50%. The veins on their breast, legs and abdomen may be more visible, and they may also have a stuffy nose due to the augmented blood flow. Around the 22nd week, they will generally have gained 4.5 or more kilos, the additional weight being distributed to both the mother and the fetus. On average, a pregnant woman can expect to gain 1 to 2 kilos in the first 12 weeks, and slightly less than half a kilo a week for the rest of the process.

Appetites naturally tend to increase in order to support the rapidly growing baby. However, pregnancy should not be an excuse to overindulge with food. For balanced nutrition, a pregnant woman only needs around 300 extra calories per day. So it's better to go for extra portions of vegetables and fruits, instead of sweets and desserts. Many pregnant women report intense mood swings, in particular during the first and third trimesters. A common and normal situation.

At the start of the second trimester, the baby is about 8 centimeters long, "from crown to rump" (the fetus is measured from the top of the head to the bottom because its legs are curled up to its stomach). By the end of the second trimester, the fetus will grow to about 23 centimeters, or even more.

Developing babies will begin to hear sounds, such as mom's heartbeat, by around the 18th week. Then their hearing will improve and they will be able to hear their mother's voice. Babies' eyes may open as early as the 20th week, but they cannot see anything until the third trimester. As their nervous system develops, they will become able to feel mom's movements and perceive their environment by the end of the second trimester.

Picture: Pregnancy - Medical Gallery of Blausen Medical (Wikimedia Commons)