There's a new form of emergency contraceptive on the market. On Friday, the F.D.A. approved ella, a pill that can be taken as many as five days after unprotected sexual intercourse to prevent pregnancies, NYTimes.com reported. Until now, Plan B, which is now available over-the-counter to women 17 and older and is effective for no more than three days, has been the preferred emergency contraceptive. Plan B cuts the risk of unplanned pregnancy from 1 in 20 to 1 in 40 and looses its effectiveness gradually as days go on. In contrast, ella, which is available by prescription only, is just as effective on the fifth day as it is on the first day after unprotected sex and cuts the risk of unplanned pregnancy from 1 in 50. Studies reveal that ella is less effective in obese women. Common side effects associated with the new pill's use include mild to moderate headaches, nausea, abdominal pain, painful menstrual cramps, fatigue and dizziness.