The Shettles method is a form of conception manipulation designed to help people create a fetus of their desired sex. However, there is no evidence to suggest the Shettles method works.

The following article explores the Shettles method, and the science and theories behind it.

It also discusses why it is not a very accurate method.

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According to a 2019 article, in the 1960s, a doctor named Landrum Shettles began researching sperm and how they influence the sex of a developing fetus. He proposed that sperm had key differences based on the sex chromosome they carried — X or Y.

The basic theory behind the Shettles method is that people could use the differences between male (Y) and female (X) sperm to manipulate the sex of the fetus.

The method proposed ideal times to have intercourse, preferential sexual positions, and the pH of bodily fluids to determine which sperm reached the egg first, theoretically determining the sex of the fetus.

Dr. Shettles stated he found differences between male and female sperm.

He concluded that the key differences between the sperm were as follows:

Male spermFemale sperm
Size and shapeSmall with rounded headsLarge with oval-shaped heads
ChromosomeMale-producing Y chromosomesFemale-producing X chromosomes
Ideal environmentsSurvived for longer and swam better in alkaline conditions found nearer the cervix.Survived for longer and swam better in acidic conditions found in the vagina.
Swim speedFasterSlower

Dr. Shettles claimed that these differences affected both how quickly the sperm could reach the egg and their ability to survive in the vagina.

He also pointed out that the pH of the cervical secretions became more alkaline the nearer to ovulation a person was. As a result, he concluded the timing of intercourse was important depending on the desired sex of the fetus.

However, in a 2020 study, researchers found that the differences between male and female sperm were limited to the content of their DNA. They said that it was still unclear if the difference in the DNA could affect aspects such as speed and fragility.

According to the Shettles method, conceiving a female fetus works best under the following factors:

  • Sexual position: Those conceiving should have sexual intercourse face-to-face and perform shallow penetration. This theoretically allows the sperm to pass through the acidic environment in the vagina.
  • Timing of intercourse: Sexual intercourse is encouraged between the end of menstruation and three days before ovulation. People should refrain from sexual intercourse 2–3 days before ovulation.
  • Timing of the female orgasm: Dr. Shettles suggested that the secretions that appear during the female orgasm are alkaline. As a result, the female should refrain from orgasming until after the male has ejaculated.
  • Douching: Dr. Shettles suggested that a female should douche using 2 tablespoons of white vinegar to 1 quart of water to create an acidic environment.
Douching and safety

It is important to mention that vaginal douching is not safe. The Office on Women’s Health notes that douching can lead to health problems and may be linked to difficulties getting pregnant, ectopic pregnancies, and preterm labor.

They are also connected to vaginal infections, such as yeast infections and bacterial vaginosis. In addition, if a person has a vaginal infection, douching can push the bacteria into the uterus, ovaries, and fallopian tubes. This can result in pelvic inflammatory disease.

Learn more about douching here.

According to the Shettles method, conceiving a male fetus works best based under the following factors:

  • Sexual position: Those conceiving should have sexual intercourse from the rear to encourage deep penetration and deposit the sperm near the cervix.
  • Timing of intercourse: People should refrain from sexual intercourse from the beginning of the menstrual cycle up until the day of ovulation and the following three days.
  • Timing of the female orgasm: The female should orgasm before the male ejaculates.
  • Douching: Dr. Shettles suggested that a female should douche using 2 tablespoons of baking soda to 1 quart of water to produce an alkaline environment.

There is limited evidence to suggest the Shettles method works.

A 2016 study notes that there does not appear to be any evidence to suggest that the pattern of intercourse has any effect on the sex of the fetus. A study from 2020 also notes that there are no, or very little, differences between sperm.

According to Dr. Shettles, his patients had an 80% success rate when using his proposed methodology. However, he also admitted that the method was not a guarantee.

The sperm that penetrates the egg first determines the sex of the fetus.

A person’s assigned natal sex is a result of a combination of sex chromosomes. Egg cells contain an X chromosome and sperm cells contain either an X or Y chromosome.

The sperm that penetrates the egg first will determine the sex of the fetus.

Typically, a combination of XX results in a female fetus and a combination of XY results in a male fetus.

However, other people may have different combinations of chromosomes that differ from the typical male or female chromosomes.

Learn more about chromosomes and intersex here.

There are no methods, including the Shettles method, that can guarantee a person will conceive a fetus of the desired sex.

However, a couple who uses intracytoplasmic sperm injection, a type of in vitro fertilization, may be able to select their fetus’ sex. The process involves implanting a single sperm into an egg outside of the body.

Prior to implanting the embryo in the body, doctors can run a test called the preimplantation genetic diagnosis to determine the gender of the developing embryo. A couple could then select the sex they desire.

The Shettles method provides an outdated guide on how and when to have intercourse to determine the sex of a fetus.

There is conflicting research about whether the method works, and more recent research states that there are very little or no differences in the sperm regarding shape, size motility, swimming pattern, or pH. The only difference is the DNA they carry.

Although there does not appear to be any harm in trying the Shettles method, it appears unlikely to determine the sex of the fetus. Additionally, people should avoid douching as this can lead to health concerns.