<prompt> Most common cause of spontaneous abortion in first trimester:Chromosomal anomaliesUterine anomaliesAntiphospholipid antibody syndromeHypothyroidism  <response>: Ans: A Chromosomal anomalies Ref: Dutta: Textbook of Obstetrics 7th ed pg 160Explanation:COMMON CAUSES OF MISCARRIAGEFirst TrimesterGenetic factors Endocrine Immunological disorders InfectionUnexplainedSecond TrimesterAnatomicCervical incompetenceBicomuate uterusSeptate uterusUterine synechiaeUterine fibroidMaternal medical illnessUnexplained 