A suitable indicator for calculation of pregnancy is trimesters. This would be from the date of your last menstrual cycle that is around 40 weeks in total. The first stages of pregnancy would be from week 1 to week 12, or it could work out to be around 3 months. The second trimester of your pregnancy is between week 13 to 27 and the last period is from 28 weeks to 40 weeks. Your baby is going to change from week to week and you can easily figure it out with the help of a baby growth video.
It is the time frame after fertilization, whereby the fertilized egg forms blastocyst. During this implantation a series of physical along with hormonal changes are observed in the body. The period between third to eight weeks goes by the term embryonic stage and here the embryo goes on to form major organs of the body. At this stage the embryo is vulnerable to a host of foreign substances and this could be in the form of radiation, alcohol coupled with infection diseases.
Once the embryo increases in length it is known as fetus. Till now it has grown from the size of a grapefruit to a fist. This is a stage of some rapid development as the embryo emerges in the form of a small seed.
If this happens to be your first pregnancy, then the fetus tends to move in between 18 to 22 weeks and this is after the date of your last menstrual cycle. Though the fetus by now would be moving up and down, the movement would not have been that strong for you to sit up and take notice. In fact towards the starting the fetal movements could be so gentle and you may not be able to figure out what you are experiencing. A video of baby growth week by week will clear things at a much wider level. If you have been pregnant earlier then you would have noticed some movement and this could be sometime between week 16 to 18. At this juncture the fetus is still working on the body fat whereby you are putting in a lot of weight.
This is the time period that starts from week 28 till the time one gives birth. By the end of the 40th week your due date ends in an ideal situation a pregnancy can occur anytime between weeks 37 to week 40. At this point of time, the fetus tends to become larger where the body organs also become mature. It is known to move at frequent levels between weeks 27 to 32.
Once it touches week 32, the fetus tends to become so big in size that it can move around the uterus. It is another fact that the movement may seem a lot less. Once this semester is reached the baby stretches down to a head down position so that they can make their way through the birth canal.