<prompt> Risk for postnatal urinary abnormality is severe if Renal pelvic dilatation is --- in third trimester?4 to 7mm7 to 9mm9 to 15mm15mm  <response>: Risk for Postnatal Urinary Abnormality According to Degree of Renal Pelvis DilatationDilatationSecond trimesterThird trimesterPostnatal abnormalityMild4 to 7mm7 to 9mm12Moderate7 to 10mm9 to 15mm45Severe 10mm 15mm88Ref: Williams Obstetrics; 25th edition 