IUI (intrauterine insemination) can be combined with sperm sorting techniques to influence your baby’s sex, but it’s far from a guarantee. The most studied method, called the Ericsson method, has reported success rates of roughly 74% to 85% depending on whether you’re selecting for a girl or a boy. That’s better than the natural 50/50 odds, but it’s not the near-certainty you’d get with IVF and genetic testing. And depending on where you live, non-medical sex selection may not be legally available at all.
How Sperm Sorting Works With IUI
The basic idea behind sex selection with IUI is separating sperm before insemination. Sperm carrying an X chromosome (which produces a girl) contain about 2.8% more DNA than sperm carrying a Y chromosome (which produces a boy). That tiny difference is the basis for every sperm sorting technique.
The most widely known approach is the Ericsson method, developed in the 1970s. A semen sample is layered over columns of albumin, a protein solution. Sperm swim downward through the layers at different speeds based on their size and weight, which allows technicians to collect a sample enriched with either X or Y sperm. After microscopic examination, about 80% of sperm in a Y-enriched sample carry the Y chromosome. The enriched sample is then used for a standard IUI procedure.
A more advanced technique called MicroSort used fluorescent dye to stain sperm DNA, then sorted them with a laser-based system called flow cytometry. Because X-bearing sperm glow slightly brighter (more DNA absorbs more dye), the machine could separate them with greater precision. MicroSort achieved roughly 88% X-bearing sperm when sorting for girls and about 74% Y-bearing sperm when sorting for boys. During clinical trials, it improved the chances of selecting a girl to approximately 90% and a boy to around 85%. However, the FDA did not approve MicroSort after its extended review, and it has not been available in the United States since 2012.
Realistic Success Rates
With the Ericsson albumin method, the numbers from clinical studies show an 85% success rate for selecting a boy and about 74% for selecting a girl. Those percentages reflect the sex of babies actually born, not just the purity of the sperm sample. So if you’re trying for a boy using this method, roughly 15 out of 100 couples will end up with a girl instead.
It’s also worth remembering that IUI itself doesn’t guarantee pregnancy. Per-cycle pregnancy rates for IUI typically range from about 10% to 20%, depending on your age, fertility status, and whether you’re using medications to stimulate ovulation. Sperm sorting adds a layer of complexity to a process that already requires multiple attempts for many couples. You may need several cycles before achieving pregnancy, and each cycle carries that same margin of error on sex selection.
How IVF Compares for Sex Selection
If accuracy is your priority, IVF with preimplantation genetic testing (PGT) is the only method that approaches 99% reliability. During IVF, embryos are created in a lab, and a few cells are biopsied from each one. Genetic testing reveals the chromosome makeup, including whether the embryo is XX (female) or XY (male). You and your doctor then choose which embryo to transfer.
The tradeoff is significant. IVF is far more invasive, requiring hormone injections, egg retrieval under sedation, and embryo transfer. It also costs substantially more, often $15,000 to $25,000 or higher per cycle. IUI with sperm sorting is less expensive, less physically demanding, and doesn’t require creating embryos in a lab. For couples who are otherwise fertile and simply have a preference, the lower accuracy of IUI-based methods may be an acceptable tradeoff for a much simpler process.
Where Sex Selection Is Legal
In the United States, sex selection for non-medical reasons is legal. The American Society for Reproductive Medicine (ASRM) has stated that fertility clinics are free to offer or decline non-medical sex selection, as long as they do so in a nondiscriminatory manner and inform patients of their policy. Some clinics will happily help with “family balancing” (choosing the sex you don’t already have), while others only consider embryo quality when deciding which to transfer. If your clinic doesn’t offer it, you can seek care elsewhere.
Outside the U.S., the picture is very different. At least 36 countries have laws restricting or prohibiting sex selection for non-medical purposes. The United Kingdom, Canada, Australia, China, India, Turkey, and 25 European countries all restrict the practice. The European Convention on Human Rights and Biomedicine explicitly states that assisted reproduction techniques “shall not be allowed for the purpose of choosing a future child’s sex, except where serious hereditary sex-related disease is to be avoided.” Some countries, including Austria and Switzerland, ban sex selection for any reason. In these countries, sex selection is only permitted when a child would be at risk for a serious condition passed through the X chromosome, such as hemophilia or Duchenne muscular dystrophy.
What to Expect at a Clinic
If you’re in a country where non-medical sex selection is permitted and you want to try IUI with sperm sorting, the process looks similar to a standard IUI cycle. Your partner provides a semen sample, which is processed through the albumin gradient separation. The sorted sample is then inserted into your uterus through a thin catheter, timed to coincide with ovulation. The procedure itself takes only a few minutes and is typically painless.
Not every fertility clinic offers the Ericsson method or other sperm sorting services. You’ll likely need to call ahead and ask specifically about sex selection options. Some clinics may recommend going straight to IVF with genetic testing if sex selection is your primary goal, especially if you’re over 35 or have any underlying fertility concerns. The reasoning is straightforward: if you’re going to invest time and money, IVF gives you both a higher pregnancy rate per cycle and a near-perfect accuracy on sex.
For couples who are fertile, younger, and comfortable with a 75% to 85% chance rather than near-certainty, IUI with sperm sorting remains a less intensive option. Just go in knowing the odds. There is no version of IUI-based sex selection that guarantees the outcome.