Koreans drink seaweed soup on their birthdays to show respect for their mothers, because Korean women drink seaweed soup after giving birth. Pregnant women drink seaweed soup because seaweed soup is rich in calcium and iodine, which is the best tonic for children's growth and maternal health, especially for mothers who breastfeed their children. In Korea, seaweed soup has always been considered as a postpartum tonic for pregnant women. In the first three days after delivery, women should drink clam seaweed soup because it has the significance of preventing killing, and then beef and chicken will be added to the seaweed soup. Pregnant women can't bargain for kelp, because it is said that the lower the price of kelp, it means that the life expectancy of children will be shortened in the future. When cooking seaweed soup, you can't shred kelp, but tie it into a string with a rope, because there is a legend in Korean custom that shredding kelp will mean that children will have dystocia. Therefore, Koreans drink seaweed soup on their birthdays to commemorate their mothers' pain during childbirth and express their gratitude to their mothers.