13w 2d - Finding out gender??


I hate to sound ignorant but how are all of you finding out the gender of your babies so soon?! I had my first daughter 6 years ago and my sister told me something about some blood test?? How do I ask my dr for this? Do most insurances cover that or? This is crazy! I’d love to know because I really would hate to wait until I’m like 18-20 weeks for the sono! Lol