Aihhh sakit pinggang tu memang common masa pregnant, especially kali pertama sebab body kita sedang adjust kan, 18 weeks the ligaments are stretching and your belly is getting heavier, so that hardness and back pain is pretty normal lah. A few of my mum friends had the same thing, tapi sebab ni first pregnancy ko better check with your doctor or midwife just to make sure everything okay, especially kalau sakit tu getting worse or ada spotting jugak, they can give you some tips on posture or maybe a maternity belt yang boleh help relieve the pressure on your back.