Question: I am an OB/GYN in the bay area and I have a patient that is interested in having a baby girl. She asked about “sperm spinning” as a method of gender selection and whether it would be useful in her situation.

Answer: Our office receives a lot of questions from patients and members of the public about sex selection. Our location in the very liberal San Francisco may be cause for the increasing demand we see in having a baby of a predetermined gender. People are also well informed about what can be achieved with modern technology, and since sex selection is a reality, there’s definite demand for it.

The procedure that you ask about, “sperm spinning” is better known in the medical and scientific communities as the “Ericsson Method”. The technology was developed by the German scientist Dr. Ronald Ericsson and has been licensed in the US and internationally since the early 1970′s. It takes advantage of the fact that sperm bearing a Y chromosome (that would make a boy) are very slightly lighter than X-chromosome bearing sperm (that would make a girl). The distribution of X and Y bearing sperm in a normal sperm sample is equal, but Ericsson’s method uses gentle centrifugation of sperm through a slightly viscous fluid to segregate the heavier (girl) sperm from the lighter (boy) sperm. Since the difference in the weight of the 2 types is so slight (about a 3% difference in amount of DNA), a perfect separation cannot be achieved. Ericsson’s website (www.childselect.com) claims a 78-85% success rate in couples seeking a boy and a 73-75% success rate for girls. At PFC, we do not endorse or recommend this method of sex selection, nor can we verify the above success rates. As far as we know, couples availing of sperm spinning are not given details of how well purified their samples are prior to using them for insemination.

A more reliable method for separating sperm in our opinion is the “Microsort” technique offered at the Genetics and IVF Institute (www.givf.com) in Fairfax, Virginia. The technique was developed originally by Dr. Lawrence Johnson at the US Department of Agriculture, and was later refined for use in humans in collaboration with GIVF. Microsort also takes advantage of the small difference in DNA content between “boy” and “girl” sperm. The sperm are dyed with a stain that binds to DNA and then an instrument called a flow cytometer can effectively separate populations of sperm based on how much dye they have incorporated. The Microsort scientists test a small aliquot of every separated sample to determine the exact enrichment that they have achieved. According to the latest figures posted on their website (microsort.net) the average enrichment for X-bearing sperm is 88% with 91% (525/574) of babies born being female. The technique is less effective for Y-bearing sperm with an average sample purity of 73% and 76% (127/152) of babies born being male. Bear in mind that the figures for babies born might be distorted since some patients may have terminated pregnancies that were not the gender that they were seeking. You may also have noticed from the GIVF data that there’s more demand for girls than boys. This is likely due at least in part to the fact that X separations work much better and therefore may be used more, but Dr. Ericsson’s website also claims a much stronger female demand even though his technology supposedly works better for boys. We do support the use of Microsort sperm here at PFC but there are limitations on the use of this technology. First, the sperm can only be separated in 2 laboratories in the US, (Fairfax and Huntington Beach in southern California), and the Microsort researchers prefer that you attend in person to give a fresh sperm sample. Second, the technology is currently only offered under an FDA approved clinical trial, and you have to be doing family balancing or trying to avoid a sex-linked disease in your family to be enrolled. For most people, unless you already have a child of a different gender from the one you are seeking, you won’t be able to participate in this FDA study.

Last, but not least is preimplantation genetic screening (PGS) that can be used to tell the sex of embryos created during in vitro fertilization (IVF). We feel that this technology is the most accurate of the sex determining strategies since there’s less than a 3% chance of a misdiagnosis. Embryos generated in an IVF cycle are subject to a biopsy procedure on the third day of growth that allows a single cell from the embryo to be analyzed to see if it has 2 X chromosomes (female) or X and a Y chromosome (male). IVF with PGS is the most accurate method for sex selection, but also the most involved and the most expensive. The Ericsson method is the easiest and the cheapest, but carries a greater risk of being inaccurate.

Joe Conaghan, PhD

Here are some images from the different techniques that can be used for gender selection

To read more about this process, see our Ask The Experts post

Pacific Fertility Center Team
Left to Right: Front: Philip Chenette, MD, Isabelle Ryan, MD, Carolyn Givens, MD
Back: Joe Conaghan, PhD, Carl Herbert, MD, Eldon Schriock, MD

Question: My husband and I have two boys and want to have a girl.
What are our options?

Answer: Gender selection is a complicated and difficult issue. Ethics aside, there really are only two proven methods. The first is a technique of sorting sperm cells called Microsort. If there is a healthy number of motile sperm present (no significant male infertility), the husband can fly to Southern California to the Microsort lab and have the sperm sorted. That sperm can then be used to inseminate the wife at Huntington Reproductive Center in Laguna Hills or can be frozen and shipped back to PFC for use in IVF. Because the technique results in such poor recovery of sperm, insemination may take several tries. This is why most of our patients will use the sperm in conjunction with IVF, in which case we can inseminate by single sperm injection (ICSI) several of the wife’s eggs, producing and then transferring embryos back to the uterus, and giving the couple a better chance of success. The sperm sorting method is much more efficient if the gender desired is female (see Microsort Facts below). We receive a report from Microsort about the estimated percentage of sperm that are X-bearing (female) vs. Y-bearing (male). Usually, for a female, that is about 85% and most couples interested in a girl are comfortable with those odds. For a male, the odds are lower (about 73%) and therefore, if a boy is really desired, most couples look to PGS (Pre-Implantation Genetic Screening).

With PGS, the patients undergo IVF with ICSI to create the embryos, and when the resulting embryos have 5-8 cells, a single cell is removed and analyzed for a number of chromosomes, including X and Y. If the couple wishes to transfer only the embryos of one gender, they will have to decide what to do with the remaining embryos. The technique is close to 93% accurate, which is a huge advantage over Microsort if male gender is desired. However, our most recent statistics with PGS indicate implantation rates tend to be lower. We do suspect that the procedure of removing a cell from the embryo may be decreasing the chances of successful implantation.

There are many more complex issues involved with PGS so we require our patients considering this process to meet with a genetics counselor (we work with the Perinatal Genetics program at California Pacific Medical Center for this counseling) to discuss the implications of undergoing this process in more depth.

– Carolyn Givens, M.D.

Microsort Facts • Sperm sorting technique

Two locations: Virginia and Southern California

Must be younger than 40 years old (or using egg donor)

Must be for Family Balancing (not first child)

Low % of sperm recovered

Efficiency for a girl is about 85%

Efficiency for a boy is about 73%

For more info, visit the website: www.microsort.net