Ahhh sakit perut sebelah kiri masa early pregnancy memang common, especially around 12 weeks when everything is stretching and shifting, tapi since it's your first baby, better check with your gynae just to be safe, a few of my mum friends had the same worry and the doctor just did a quick scan to confirm everything was fine, which really put their minds at ease! Is it sharp pain or dull cramps? Kalau paired dengan spotting or very severe, jangan tunggu, go to your clinic straightaway.