Uy, congrats sa baby mo! Ang corpus luteum is totally normal, yan yung small cyst-like structure na nabubuo after ovulation, and it's what helps maintain your pregnancy sa early weeks, so it's a good sign talaga! A few of us moms saw the same thing sa aming first ultrasound and our OBs said it's nothing to worry about, it usually disappears on its own by second trimester. But since this is your first time and gusto mo ng peace of mind, definitely ask your OB about it sa next visit, they'll give you the full picture and reassure you. Wishing you a healthy pregnancy, mama!