<prompt> Most common abnormality in first trimester abortionDefective genesCervical incompetencePlacental membrane abnormalityRetroversion  <response>: A. i.e. Defective genes 161 - Dutta Genetic factor 50 of early miscarriage are due to chromosomal abnormality in the conceptus. Autosomal trisomy is the commonest 50 cytogenic abnormality in FIRST TRIMESTER Cervical incompetence congenital or acquired is the most common abnormality in SECOND TRIMESTER The cause of fetal death in ectopic pregnancy is postulated as vascular accident Most valuable diagnostic test in a case of suspected ectopic pregnancy is - Transvaginal USG 