Salam! Ini very normal during pregnancy, hun, uterine contractions (Braxton Hicks) boleh jadi from 16 weeks onwards, lagi-lagi during intimacy sebab orgasm atau stimulation trigger them. A few of my mum friends kena jugak, especially in second trimester, and they said practising the breathing like you're doing tu memang help relax the uterus. Tapi since you're worried and it happens every time, better check with your doc just to make sure everything's okay, especially to rule out any other causes yang mungkin perlu attention. In the meantime, go slow lang with your partner, komunikasi jer if you need to pause, and that breathing technique you found memang the right move!