It has been known for many years that the gender of a child is determined by the sex chromosome carried by the sperm. Sperm bearing an "X" chromosome (men have both "X" and "Y" bearing sperm), when united with the "X" chromosome from the female's egg (females only produce "X") will result in an "XX" pregnancy that produces a female. If a sperm bearing a "Y" chromosome unites with the "X" chromosome from the female, an "XY" pregnancy will give rise to a male. Therefore, with a natural pregnancy or with assisted reproductive technologies, such as IUI or IVF, each pregnancy has a 50% (or one in two) chance to be male and a 50% chance to be female.
When trying to conceive a girl or trying to conceive a boy, gender selection/sex selection may be used when parents need or want a child of a specific sex. Gender selection can also help prevent the transmission of certain genetic diseases. Genetic diseases carried on the X or Y chromosome are termed "sex linked" genetic diseases. Most commonly, gender selection is performed in instances where serious sex-linked diseases, such as hemophilia or muscular dystrophy are a concern; or when some couples have children of one gender, and choose elective family balancing to help them have a child of the other gender.
Successful gender selection "methods," performed by a reproductive endocrinologist, include various sperm separation techniques and/or IVF with PGS (Preimplantation Genetic Screening). Unproven therapies such as 'coital timing,' varying sexual positions, or vitamin programs do not work and should not be relied on. Genetic screening (PGS) however, can be very, very effective.
Sperm separation techniques in the lab safely separate sperm (various methods) to allow the majority of the sperm capable of producing the desired gender ("X" sperm or "Y" sperm) to be recovered and utilized for IUI or IVF. None of the older traditional sperm separation techniques, such as Erickson, have been able to achieve consistent gender outcome success rates over 60-75%; even the best separation methods of today, such as MicroSort® sorted sperm, combined with IUI or even traditional IVF, are generally under 85% gender success rates.
Therefore, if you want to be sure that your next child will be the gender you need or desire, note that no other gender selection method comes close to the success or reliability of IVF with PGS (greater than 99.9%). Using IVF and preimplantation genetic screening (PGS) for gender selection, male and female embryos are identified and only embryos of the desired sex are transferred to the uterus.
At our Chicago area IVF clinics, this is the method of sex selection we recommend. Whether doing PGS gender selection for prevention of sex-linked genetic diseases or for 'family balancing', the embryos can also be screened by our genetics team for aneuploidy (see above). The aneuploidy (abnormal chromosome count) screening process, employed at the time of PGS gender determination, allows for the detection of various genetic count abnormalities, such as Down syndrome- Trisomy 21 (one "extra" chromosome 21). Utilizing PGS for gender selection, IVF pregnancy success rates are similar to regular in vitro fertilization success rates and sex selection rates approach 100%.
Contact our offices in and around Chicago to learn more about gender selection. We will be happy to answer any questions you have.