The carat (ct) is a unit of mass equal to 200 mg (0.2 g; 0.007055 oz) and is used for measuring gemstones and pearls. The current definition, sometimes known as the metric carat, was adopted in 1907 at the Fourth General Conference on Weights and Measures, and soon afterwards in many countries around the world.
Depending on your cycle length the most fertile days in the cycle varies: If you have 28 days between periods ovulation typically happens on day 14, and the most fertile days are days 12, 13, and 14. If you have longer cycles, say 35 days between periods, ovulation happens on day 21 and the most fertile days are days 19, 20, and 21.
According to researchers at the National Institute of Environmental Health Sciences, only about 30 percent of women actually have their fertile period between days 10 and 17 of their menstrual cycle. This adds validity to what many women with unplanned pregnancies have long suspected. Researchers found that the potential for fertility exists on almost every day of a woman's menstrual cycle. Most women in the study were between the ages of 25 and 35, the age when menstrual cycles are at their most regular.