Personal fertility monitors for contraception.

discovered the synthetic progestin used in the first birth control pill, expressed concern about existing contraceptive methods and predicted fertility awareness and family planning through biochemical measurement of endogenous hormones at home. Today, multiple fertility monitors are available that provide couples with accurate biochemical measurement of the fertile window to plan or avoid pregnancy, without potential side effects associated with other contraceptive methods. In this article, we review two new hormone-based personal fertility monitors that can be used for contraception. Fertility monitoring involves biochemical identification of the fertile period and avoidance of intercourse, or use of other precautions, during this brief stage. The current understanding of the menstrual cycle is that an ovum in wo men of reproductive age is released once per cycle and is typically fertilizable for 12–24 hours, whereas sperm are typically viable for three to five days. In a series of studies by the World Health Organization in the 1970s, measurable changes in serum estradiol levels were found to signal the onset of potential fertility, and surges in luteinizing hormone levels were confirmed as the best predictor of impending ovulation. Subsequently, rising urine levels of estrone-3-glucuronide were found to correlate with rising serum estradiol levels and potential fertility, whereas surges in urine levels of luteinizing hormone accurately predicted impending ovulation. These findings showed that serum samples were no longer needed.