Most common cause of abortion in first trimester is-

Ans. is 'a' i.e., GeneticCauses of first trimester abortiono Genetic: Majority (50%) of the early miscarriages are due to the chromosomal abnormality of the conceptus.Autosomal trisomy is the commonest cytogenetic abnonnality. Trisomy 16 is the most common.o Endocrine and metabolic (10 - 15%)Luteal phase defect, deficient progesterone, thyroid abnormalities, diabetes mellitus. o Anatomical abnormalities (10 - 15%)Cervico - uterine factors (mostly related to second trimester abortion) - cervical incompetence and congenital malformation of the uterus.o Infections: (5%)Can cause early as well as late abortions.o Immunological disorders (5- 10 %)o Blood group incompatibilityo Premature rupture of membraneso Environmental: Cigarette smoking, alcoholo Unexplained.