Symptoms may not start for 6 to 12 hours after exposure to the ultraviolet light. Symptoms include: 1  A feeling that something is in the eyes (foreign body sensation). 2  Sensitivity to light (photophobia). 3  Tearing.
It is divided into three stages, called trimesters: first trimester, second trimester, and third trimester. Conception to about the 12th week of pregnancy marks the first trimester. The second trimester is weeks 13 to 27, and the third trimester starts about 28 weeks and lasts until birth.
A trimester is a third of a typical pregnancy. So if a pregnancy is 9 months, a trimester is 3 months long. The first and second trimester each have 13 weeks, while the third trimester has 14 weeks. Determining how far along you are in a pregnancy can get confusing.