- How It Works
- How Sex Is Determined
- Shettles Method
- Preconception Diet
- Reasons for Choosing Gender
There are two scientifically proven methods that can help you choose the gender of your baby:
- Preimplantation genetic testing (PGT) to select fertilized eggs (embryo) of the desired sex, which is followed by the transfer of only those desired embryos into the womb (uterus).
- Preconception sperm separation by flow cytometry (where available), which is followed by the use of sperm with the desired sex for in vitro fertilization (IVF) in a test tube (with or without intracytoplasmic sperm injection) or in vivo fertilization via transfer of only desired sperm into the uterus.
How do gender selection methods work?
Preimplantation genetic testing (PGT)
PGT for sex can be performed by using one or more cells from an embryo before it gets implanted in the uterus. The embryo (called the blastocyst) is extracted out of the uterus before implantation. Genetic testing is done on 5-7 cells biopsied from the outer layer of the blastocyst.
The blastocyst is frozen as the genetic analysis by the standard method can take several days. The desired thawed blastocyst is then transferred into the uterus in the next cycle. Some advanced institutes can complete the genetic analysis on the same day and transfer the blastocyst the next day.
PGT is an expensive technique and offered only in conjunction with IVF. Success rates after the procedure are decent, and no adverse effects on offspring have been reported. However, long-term data is not available.
Preconception sperm separation by flow cytometry followed by IVF and in vivo fertilization by transfer into the uterus
This method helps segregate the X-chromosome-bearing sperm from the Y-chromosome-bearing ones using a dye followed by flow cytometry. A fluorescent dye (bisbenzimide) coats the sperm. Ultraviolet (UV) beams are then used to excite the sperm coated with fluorochrome. X-chromosome containing sperm have increased fluorescent intensity due to higher genetic material in them. This allows the sperm to be separated into X- and Y-bearing sperm.
The success rates in terms of pregnancies of the desired gender achieved are 93% for females and 82%for males. No side effects have been reported in 29 children out of 1200 that have been followed up since 1998.
MicroSort that carries out this gender selection method had failed to obtain the FDA’s approval for patient use in 2011. It has not been available for use in the United States as of March 2012 but is available in several other countries. No flow cytometry-based sperm segregation technique is available in the United States.
How is the sex of your baby determined during conception?
An adult human cell contains 23 pairs of chromosomes (46 in total). Of these, 22 pairs code for the development of tissues other than the sexual organs. The remaining pair of chromosomes are called sex chromosomes, which are of two types: X and Y.
A male has an X and a Y chromosome, forming their 23rd pair, whereas a female has two X chromosomes, forming their 23rd pair. The sex of a child depends on whether a 22+X-chromosome or 22+Y-chromosome bearing sperm from the man fertilizes the egg (ovum) containing 22+X chromosome from the woman.
Although the probability of delivering a male or female child in pregnancy is affected by a variety of factors, the probability that a male will be delivered remains constant at approximately 51%. This is independent of the sex of previous siblings and the age of parents during coitus.
Is the Shettles method of gender selection effective?
The Shettles method of sex selection is based on the timing of coitus, sexual position, depth of penile penetration, and presence or absence of female orgasm.
Timing of intercourse in reference to ovulation signs is based on the belief that Y-bearing chromosomes move faster due to their small size and have a shorter life. However, scientific studies with rigorous designs have found that the timing of intercourse in relation to ovulation do not influence the sex of the fetus.
The Shettles method also proposes that the depth in penile penetration, coitus in a position where the male penetrates from the rear position of the female, and presence of female orgasm increases the chances of Y-bearing sperm to reach and fertilize the egg before X-bearing sperm. This hypothesis, however, is not supported by scientifically proven data.
Does a preconception diet play a role in gender selection?
There is a hypothesis that a female can:
- Improve the chances of having a female child by increasing her dietary intake of calcium and magnesium.
- Improve the chances of having a male child by increasing her dietary intake of sodium and potassium.
These are, again, scientifically unproven claims.
Why would couples want to choose the gender of their baby?
1. Personal preference of a child of a specific sex
The parents may both want to have a child of a particular gender. This choice may depend on the cultural stereotypes, economic conditions, or social factors, such as inheritance of property.
2. To achieve a “complete” or balanced family with children of both sexes
Couples may mutually decide to have a second child of the opposite sex as the first to have a sense of balance and completion of their family.
3. To avoid X-linked diseases
Some couples may want to avoid passing a sex-linked genetic disease to their baby. Some females are carriers for over 350 X-linked diseases, even if the disease has not manifested and affected them. Examples of such diseases include hemophilia and Duchenne muscular dystrophy, where there is a recessive gene on the X-chromosome.
For these couples, preimplantation selection of only female fetuses for embryo transfer can prevent situations in which they have to struggle with the decision to terminate a pregnancy with a possibly unaffected male.
4. To reduce the chances of the baby having a specific disorder
Some couples may want to select the gender of their baby to reduce the risk of having a child with a disease more common in a particular gender. For example, if a couple has more than one affected male child with autism spectrum disorder, their chance of having another affected male child with their next pregnancy is25%. They may opt to have a female baby to reduce this risk.
Diseases more commonly found in a particular gender as as follows:
Diseases more common in males
- Autism spectrum disorder
- Pyloric stenosis
- Hirschsprung disease
Diseases more common in females
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Health Solutions From Our Sponsors
Cleveland Clinic. Boy or Girl — Can You Choose Your Baby’s Sex? https://health.clevelandclinic.org/boy-or-girl-can-you-choose-your-babys-sex/
Bendikson K, Racowsky C. Sex selection. UpToDate. https://www.uptodate.com/contents/sex-selection
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