Mama, please check with your OB first before using it, kahit na-prescribe na yan before, mas okay na i-confirm kung safe pa rin for 18 weeks kasi bago na ang dosage requirements mo ngayong second trimester. Your doctor will know best kung okay pa yan for you and baby ngayon, okay? Don't hesitate to message your OB clinic or call them, mabilis lang sagutin nila yan, promise!