Sex, particularly enthusiastic sex, and sex without sufficient lubrication, are a problem for most of us. And if you have not had sex recently, you will likely experience some abrasion and rawness. This is not unusual, but can be enough to give yeasts a start. Once your tissues are split open, conditions help the yeasts move in. So while there are inevitably times when you will experience abrasions, don't hestitate to use a non-irritating lubricant like KY jelly if you think you might need one.
Yeasts can go on a rampage until things get back to normal.
After ovulation, your vaginal pH shifts to the alkaline in response to your hormonal cycle. The effects of birth control pills and pregnancy place your hormone level in a similar range. If you have recurring yeast infections late in your cycle, during your period, while you are using birth control pills, or while pregnant, you can practice a little prevention, which I will outline later. If you are experiencing a lot of yeast infections, see if using a condom makes the difference. Antibiotics can kill off the friendly inhabitants of your vagina, allowing yeasts to grow without restraint.