Sayang, brownish discharge dalam second trimester memang boleh jadi normal, banyak mommies I know pun ada, especially kalau ada spotting after intercourse or cervical irritation. Since you're not having cramping, that's a good sign, but honestly you should still WhatsApp your gynae or clinic just to get checked and put your mind at ease, brownish vs bright red matters, and doc needs to see lah to be sure semuanya okay with the baby. A few of my mum friends went in for a quick scan and it turned out fine, tapi better safe than sorry kan, especially at 18 weeks. Keep an eye on the colour and amount, and if it gets heavier or you start having cramps, go straight in