P01.02: Gender differences in the foetuses with mega cisterna magna

To observe the gender differences in the foetuses with mega cisterna magna. 75 Chinese singleton foetus between 22 and 38 weeks' gestational age with mega cisterna magna were included in this retrospective study. All of them were diagnosed by transabdominal sonography and confirmed by fetal magnetic resonance imaging (MRI) without other abnormities. The approval of the hospital ethical committee and informed consent of the mothers were obtained. All of the foetuses were followed up until delivery by physical and imaging examination. Determination of sex and the distribution of the foetuses according to sex were recorded. In the 75 foetuses with mega cisterna magna, the number of male foetuses (57 male foetuses) was greater than female foetuses (18 female foetuses), and the proportion of the foetuses with mega cisterna magna in the male group was significantly higher than the foetuses in the female group (P < 0.05). Gender differences with mega cisterna magna exist in the foetuses. It would be reasonable to create different normal range values for male and female foetuses.