Ay alam ko yan, parang may tugging or pulling sensation diba? At 18 weeks, normal lang talaga na may ganyang sensations dahil lumalaki na ang baby at umuusbong ang ligaments mo, lalo na after taking vitamins na nakakagalaw ng tyan, pero para sigurado, mas maganda talaga i-follow up agad sa OB mo once makabalik siya ng reply, kasi sabi ng marami sa amin na moms, hindi dapat i-ignore kahit anong parang odd sensation during pregnancy. One of my friends experienced similar at nung chineck ng doctor niya, it was just round ligament pain na super normal, so baka yon lang, pero better safe than sorry talaga! Keep an eye on it and let your OB know right away if may cramping or unusual bleeding na kasama.