New advances in sex preselection.
OBJECTIVE
To review the current developments in the field of preconceptual sex selection and to discuss the moral dilemmas that accompany the scientific progress.


METHODS
A survey of the major publications on sex preselection.


RESULTS
Examination of current methods of preconceptual gender selection revealed that in vivo methods such as timing of intercourse, the use of ovulation induction medications, and artificial insemination do not appear to affect the sex ratio to a clinically significant degree. In vitro separation of X- and Y-bearing spermatozoa by gradient techniques have been reported to alter significantly the sex ratio at birth. However, these trials were noncontrolled, and molecular biological techniques could not validate that these methods indeed change the Y- to X-bearing spermatozoa ratio sufficiently for clinical use. Nevertheless recent scientific advances have made highly reliable preconceptual sex selection possible by using preimplantation diagnosis or sperm separation by flow cytometry combined with IVF. At present, these methods have been used to avoid sex-linked disorders. Both involve the invasive procedure of IVF and thus are held by most as inappropriate for nonmedical indications. However, improvement in flow cytometry output of sexed spermatozoa might provide in the near future sufficient sorted gametes for artificial insemination. This technique then will provide an available noninvasive method of sexing for social purposes.


CONCLUSIONS
Reliable preconceptual sex selection is currently possible only by preimplantation diagnosis, or sperm separation by flow cytometry combined with IVF. Both methods involve invasive procedures and are at present exclusively used for medical indications. It may be that in the near future, an improvement in flow cytometry output of sexed spermatozoa will provide sufficient sorted gametes for artificial insemination. In such a case, the medical community will be forced to take a stand, whether this reliable noninvasive method of sexing will be allowed for social purposes.
Reubinoff
B E
BE
Department of Obstetrics and Gynecology, Hadassah University Hospital, Ein-Kerem, Jerusalem, Israel.
Schenker
J G
JG
D002469:Cell Separation / Q000379:methods; D003075:Coitus; D004992:Ethics, Medical; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods; D005434:Flow Cytometry / Q000379:methods; D006801:Humans; D007315:Insemination, Artificial / Q000379:methods; D008297:Male; D012743:Sex Preselection; D012744:Sex Ratio; D013094:Spermatozoa / Q000166:cytology; D014960:X Chromosome; D014998:Y Chromosome