When a solid turns into a liquid it is called fusion, more commonly referred to as melting. When a material moves from one state of matter into another it is called a phase transition. Fusion is just...
Human pregnancy can be divided roughly into three trimesters, each approximately three months long. The first trimester is from the last period to the 13th week, the second trimester is from the 14th to 27th week, and the third trimester is from the 28th week to the 42nd week. In humans, birth normally occurs at a gestational age of about 40 weeks, though it is common for births to occur from 37 to 42 weeks.
The First Trimester of Pregnancy. 1  Week 1 & 2 â Gestational Age. 2  Week 3 â Gestational Age (Fetal Development â Week 1) 3  Week 4 & 5 â Gestational Age (Fetal Development â Weeks 2 & 3) 4  Week 6 â Gestational Age (Fetal Development â Week 4) 5  Week 7 â Gestational Age (Fetal Development â Week 5) 6  Week 8 â Gestational Age (Fetal Development â Week 6)