Hindi yan unusual sa pregnancy, mama, maraming factors na pwedeng mag-trigger like hormones, prenatal vitamins (especially kung may iron), at kung ano ate-eat mo before bed. Pero since 19 weeks ka pa lang, better to mention it sa OB mo next visit para ma-rule out kung may underlying issue or if kailangan lang adjust ng diet/timing ng prenatal, kasi bawat mama iba ang body naman talaga!