During pregnancy, it is common for women to experience the production of colostrum, a thick yellowish fluid that serves as the first milk for newborns. This discharge from the breasts is a sign that your body is preparing for breastfeeding. The production of colostrum can start as early as the second trimester, which explains why you are noticing it at 18 weeks pregnant. However, full milk production typically occurs after childbirth when hormonal changes signal your body to produce more milk. It's important to note that every woman's experience with breastfeeding is unique, so there may be variations in timing and quantity of breast milk production. If you have any concerns or questions about breastfeeding, it's best to consult with your healthcare provider or a lactation specialist who can provide personalized guidance and support.