Ay sis, that's a serious situation with the cervical shortening, you really need to check with your OB about this one kasi iba-iba ang approach depending on how short na siya and kung kailangan mo ng cervical cerclage or progesterone support, hindi lang maternity belt ang solusyon dito. A maternity support belt can help with the pressure and back pain, pero for your specific case with placenta previa and shortened cervix, kailangan talaga ng medical guidance para ma-ensure na safe at effective ang approach mo.