<prompt> Most common cause of abnormality in first trimester abortionCervical incompetanceChromosomal ahnormolityPlacental membrane abnormalityRetroversion  <response>: Chromosomal anomaly 161 - Dutta 6thCommon Causes of AbortionFirst Trimester -1. Genetic factor 50 of early miscarriage are due to chromosomal abnormality in the conceptus, Autosomal trisomy is the commonest 50 cytogenic abnormality2. Endocrine disorders LPD thyroid abnormalities DM3. Immunological disorders Autoimmune and Alloimmune4. Infection5. UnexplainedSecond trimester1. Anatomic abnormalitiesa Cervical incompetance congenital or acquired is Most commonb Mullerian fusion defects Bicomuate uterus, septate uterusc Uterine synechiaed Uterine fibroid2. Maternal medical illness3. Unexplained 