In Korea, big market is held as name of babyfair. In a large convention hall, from infant insurance to baby bottle, you can buy A to Z for your baby. Many korean parent save the date for babyfair and purchase their shopping list. I visited baby fair twice time, during pregnancy. The convention hall is densed with people, you should plan what you buy. Before entering, you should check the map where you should go. In Not only COEX, but also BEXCO, KINTEX it is held, if you are interesed with it, search for babyfair (베이비페어) and check the schedule.
513 Yeongdong-daero, Samseong 1(il)-dong, Gangnam-gu, Seoul, South Korea