"6.2 Genetic factors The finding of an abnormal parental karyotype should prompt referral to a clinical geneticist. Genetic counselling offers the couple a prognosis for the risk of future pregnancies with an unbalanced chromosome complement and the opportunity for familial chromosome studies. Reproductive options in couples with chromosomal rearrangements include proceeding to a further natural pregnancy with or without a prenatal diagnosis test, gamete donation and adoption. Preimplantation genetic diagnosis has been proposed as a treatment option for translocation carriers. Since preimplantation genetic diagnosis necessitates that the couple undergo in vitro fertilisation to produce embryos, couples with proven fertility need to be aware of the financial cost as well as implantation and live birth rates per cycle following in vitro fertilisation/preimplantation genetic diagnosis. Furthermore, they should be informed that they have a higher (50–70%) chance of a healthy live birth in future untreated pregnancies following natural conception than is currently achieved after preimplantation genetic diagnosis/in vitro fertilisation (approximately 30%). Preimplantation genetic screening with in vitro fertilisation treatment in women with unexplained recurrent miscarriage does not improve live birth rates. Preimplantation genetic screening in conjunction with in vitro fertilisation has been advocated as a treatment option for women with recurrent miscarriage, the rationale being that the identification and transfer of what are thought to be genetically normal embryos will lead to a live birth. The live birth rate of women with unexplained recurrent miscarriage who conceive naturally is significantly higher than currently achieved after preimplantation genetic screening/in vitro fertilisation (20–30%)."