Whether you're trying to get pregnant or trying to avoid it, Knowing when you're most fertile is vital information. Here are six signs that you're in your most fertile period of the month: 1. Increased libido During this time, your progesterone (a hormone) levels increase. This causes your libido to spike more than normal. It's also common to feel more hungry because of the hormone. 2. Secretions When you start to notice vaginal discharge, this is a sign you're at your most fertile. During this time you start to produce more estrogen, which results in mucus-like vaginal discharge. 3. Increased body temperature When you have high levels of progesterone, your body temperature rises. To know when this is happening, take your temperature every day when you wake up in the morning. Keeping track will allow you to notice changes, even if they're minimal. 4. Pain Many women have stomach pain during certain times of the month, and this pain is typica