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Gender Selection Glossary

(The glossary is in progress, I am adding terms as I come to them!)


An embryo with the wrong number of chromosomes. Aneuploidy is nearly always incompatible with life, and is the cause of most early miscarriages.
ART (Advanced Reproductive Technologies or Assisted Reproductive Techniques)
IVF and its variations. In general, any method of getting pregnant that requires assistance from a laboratory.
See embryo attrition.
A cell in an embryo. Each cell in an embryo is identical, because the cells have not yet begun the process of differentiation, where they become the various tissues and organs of the body.
In terms of an inherited genetic disorder, a "carrier" is a person who carries the gene for a disease, but because the gene is recessive, does not actually have the disease. A child of the carrier may have the disease, be a carrier, or neither.

Found inside the nucleus of a cell, a chromosome is a package of DNA. DNA, in turn, contains genes, which contain all the instructions for cells to create and maintain your body.

Humans have 23 pairs of chromosomes (46 in total), with one in each pair contributed by the mother, and one by the father. The last pair of your chromosomes is called the "sex chromosomes". If this pair of chromosomes is a matched pair, called XX, you are female. If this pair of chromosomes is XY, you are male.

Each cell in your body carries a complete copy of your 46 chromosomes. The exceptions are eggs and sperm, which carry only half the normal number (one from each pair), so that when the egg and sperm combine, the correct number of 46 chromosomes is formed.

An egg carries, always, a single X chromosome. Half of sperm carry an X chromosome, while the other half carry a Y chromosome. Whether a person is male or female depends on whether an X sperm or a Y sperm fertilizes the egg.

embryo attrition
"Attrition" means gradually reducing the number of something. Embryo attrition during IVF refers to fact that at the outset of the cycle, a number of embryos are formed, but at each step the number of available embryos is reduced because some will not survive, or will not be normal. In some cases, by the end of the cycle, no embryos remain, and no embryo transfer is possible.
family balancing
Using gender selection methods simply because parents prefer to choose their baby's sex, rather than medical necessity due to a sex linked genetic disorder. The term was coined to allay the stigma associated with "sex selection", which to many people equates to "boy selection" and the notion that one sex is inherently better than the other. "Family balancing" is meant to convey the desire of many couples, not to conceive the "better" gender, but to balance their families with children of both genders.
IVF, in-vitro fertilization
This was once called creating a "test tube baby" by the popular press. During IVF, a woman is given fertility drugs to stimulate the ovaries to produce multiple eggs, and the eggs are retrieved in a minor surgical procedure. The eggs are fertilized in the lab and the resulting embryos are incubated for several days. Usually, one to three embryos are selected to be transferred into the mother's uterus, and hopefully a pregnancy will result.
A sperm sorting procedure used for gender selection. Using flow cytometry, X sperm or Y sperm are sorted in a semen sample, and the resulting sorted sample is used to become pregnant using either artificial insemination (IUI) or IVF. (See MicroSort article.)
An "opposite" is a baby born after an attempt to sway or select the opposite gender. The gender method may have failed, but the resulting baby is never a failure -- just the opposite gender of what we tried for.
PGD, Preimplantation Genetic Diagnosis
A technique used during an IVF cycle, either for sex selection or to prevent an inherited genetic disorder. After embryos are fertilized, they are analyzed using genetic testing. Only embryos found to be of the desired sex, or free from the tested genetic disorder, are implanted in the mother. 100% effective for sex selection. (See PGD article.)
sex linked (or X-linked) genetic disorder
A sex linked genetic disorder is caused by a genetic error in the X chromosome, and almost always affects only males. Usually, a woman who is a carrier of an X-linked disorder will not have the disease, and her daughters also will be free of the disease, but any sons will be affected by the disease. In the case of severe disorders, sex selection is used to prevent the conception of affected males. Examples are Hemophilia A and Duchenne muscular dystrophy.
social sex selection
See family balancing.
X Sperm
A sperm bearing an X chromosome. An egg fertilized with an X sperm always results in a female. (See the Conception article.)
Y Sperm
A sperm bearing a Y chromosome. An egg fertilized with a Y sperm always results in a male. (See the Conception article.)