Even though 30 feels like the popular new birthday to dread, women entering their fourth decade seem to be at their prime. They have great careers, money to burn and, in many cases, they look better than ever.

And now we've discovered their secret: awesome sex.

Married women over 40 are having the best sex of their lives, according to a survey by Top Sante magazine. 81 percent of those polled said they were more sexually adventurous than in their 20s, while 63 percent said that sex was better because they'd become more confident in the sack over the years.

The survey also found evidence to support what we already suspected: Kids destroy all hope of a decent sex life, with 91 percent of working women with children under 10 saying their sex lives had been wrecked, and 60 percent of women enjoying more sex once their kids had moved out.

So instead of freaking out about gray hairs and looming birthdays, just chill out and embrace your forthcoming Helen Mirren years. Here's how to know if you're in a "sex rut" right now.