Risk of preterm delivery is increased if cervical length is less than :: (A) 2.5 cm, (B) 3.0 cm, (C) 3.5 cm, (D) 4.0 cm
Answer is A. During pregnancy cervical length of <2.5cm and internal os of 1cm increases the chance of miscarriage Reference: Dutta's Textbook of Obstetrics 7th edition page no 169