<prompt> Regarding monozygotic twins, which of the following is not true?USG is more useful in the first half of pregnancySex discordance can occur rarelyAlways monochoriomcMore common following ovulation induction  <response>: Ans: C Always monochorionic Ref: DC Du f fas Textbook of Obstetrics, 7th edn, Pg 201Explanation:Monozygotic twins are always identical in sex.Monozygotic twins can be:Diamniotic dichorionicDiamniotic monochorionicMonoamniotic monochorionicConjoint twinsMost common cause of multiple pregnanciesovulation inductionUltrasound in the first half of pregnancy is best to check for amnionitis and chorionicity. 