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.
Hereâs the most common breakdown, along with official weeks from the American Congress of Obstetricians and Gynecologists: First Trimester: 0 weeksâ13 and 6/7 weeks (Months 1â3) Starts with the first day of your last menstrual period (LMP) and ends with the last day of the 13th week thereafter. During your last period (which will be your last for a while), your uterus is preparing for ovulation and your body is gearing up for pregnancy, so technically, you can start counting from this point. Second Trimester: 14 and 0/7 weeksâ27 and 6/7 weeks (Months 4 â7) Starts at the beginning of the 14th week after your LMP and lasts through the 27th week of pregnancy. Third Trimester: 28 and 0/7 weeksâ 40 and 6/7 weeks (Months 7â9) Starts at the beginning of the 28th week after your LMP and ends with labor.