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.
Pregnancy by Trimester. Pregnancy is generally divided into three trimesters, each accounting for approximately 12 weeks, though the third trimester may last up to 16 weeks. Most women aren't even aware they're pregnant (or at least, aren't sure) until almost halfway through the first trimester.