Shettles method

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The Shettles Method is a child conception idea that is reputed to help determine a baby's sex. It was developed by Landrum B. Shettles in the 1960s and was publicized in the book How to Choose the Sex of Your Baby, coauthored by Shettles and David Rorvik. The book was first published in 1971 and has been in print in various editions ever since. By following the various methods outlined in the book, it is proposed that a couple can affect the probability of having a boy or a girl.

Contents

Concept

According to the hypothesis, male (Y) sperm are faster but more fragile than female (X) sperm. Further, acidic environments harm Y sperm, according to the theory, making conception of a girl more likely [1] The Shettles method aims to exploit these two factors.

The Shettles method differs from the Ericsson method, in which the semen is deposited outside the woman and time is given for the fast/slow swimmers to separate before artificial insemination takes place.

Timing of Intercourse

To have a boy, insemination should occur as close as possible to the moment of ovulation so that the faster, Y-sperm arrive first and achieve conception, according to the hypothesis. When seeking a girl, the couple should have sex 2½ to 3 days before ovulation.

Sexual Position

Shallow penetration coupled with the sperm deposited close to the entrance favors female conception because the area is more acidic, which inhibits the weaker Y sperm, according to the hypothesis. To allow the Y sperm, which supposedly moves faster, to reach the egg first, use deeper penetration to deposit the sperm at the least acidic area near the uterus opening. Intercourse should occur from 5 am and continue every 2 hours during the ovulation period. Eggs are more likely to be fertilized before 7 am known as "the peak period".

Effectiveness

Proponents claim between 75 and 90 percent effectiveness for the method.

May 19, 1998, Landrum B. Shettles, M.D., PhD dictated to his daughter, Lana B. Shettles-Callahan, an email reply to Professor Hunt concerning the presentation of choosing the sex of your baby with the following statement: “David M. Rorvik and I published in 1971 How to Choose Your Baby's Sex with revised editions in 1977, 1984, 1989, and 1997 in seventeen languages with worldwide distribution. To date, over one million copies have been sold and over 25,000 answers to the questions 'what you want' and 'what you got' with the approximate success rate of 85% for boys and 82% for girls. A bibliography of 129 references cites 28 papers of my own. The book has proven sound through the past 27 years; and, like the house in the scriptures, built on the rock rather than the sand.”

There is some disagreement among researchers as to how and whether the method works.

For example, the 1995 article "Timing of Sexual Intercourse in Relation to Ovulation—Effects on the Probability of Conception, Survival of the Pregnancy, and Sex of the Baby" in the New England Journal of Medicine concludes that "for practical purposes, the timing of sexual intercourse in relation to ovulation has no influence on the sex of the baby." The study tracked women's hormone levels daily to determine the day of ovulation. [2]

In contrast, another study from the New England Journal of Medicine (1979) found that "[our] results ... demonstrate that insemination on different days of the menstrual cycle does lead to variations in sex ratio." [3] While this second study was larger, it did not track the levels of LH in the blood but instead used cycle lengths to determine probable time of ovulation. Adding support to another aspect of the Shettles's findings related to sperm morphology, an important element in his method, a 1997 study, "Size Differences Between X and Y Spermatozoa and Prefertilization Diagnosis," published in Molecular Human Reproduction, using polymerase chain reaction-aided techniques, concluded: “Statistically, the length, perimeter and area of the sperm heads , and the length of the sperm necks and tails of X-bearing spermatozoa were significantly larger and longer than those of Y-bearing spermatozoa" [4]

Multiple studies have confirmed Dr. Shettles's findings that the larger X-bearing, female producing spermatozoa are hardier, another factor that is important in his method. Men who work at high altitudes, in high heat environments and in situations that expose them to various toxic substances and other forms of physiological stress have been reported to give birth to far more girls than boys. OBGYN News, October 15–31, 1982, for example, reported on a study of undersea divers in Australia showing that their offspring were almost 2-1 female. [5]

The researchers cited other data indicating a similar situation involving pilots of high-altitude military aircraft. Dr. Shettles contended that atmospheric pressures, tight fitting clothing and many other stressors could favor the X-bearing spermatozoa. Another study, reported upon in Discover Magazine in 1988 called "Girls from Space," found that both high altitude tactical pilots and astronauts fathered far more daughters than sons. [6]

A 2006 letter [7] published by BMJ, however, reviewing some of the research, claims that "So far, researchers have found no morphological differences between human X sperm and Y sperm", [8] ignoring prior findings to the contrary, including some published in the same journal just the year before. [9]

A May 2021 article in Fertility & Sterility reflected on a paper published in the same journal 50 years earlier that month, [10] stating that "...scientific journals such as Fertility and Sterility and The New England Journal of Medicine have continued to publish research dispelling the claims of the Shettles Method." [11]

Related Research Articles

Infertility is the inability of a person, animal or plant to reproduce by natural means. It is usually not the natural state of a healthy adult, except notably among certain eusocial species. It is the normal state of a human child or other young offspring, because they have not undergone puberty, which is the body's start of reproductive capacity.

<span class="mw-page-title-main">Artificial insemination</span> Pregnancy through in vivo fertilization

Artificial insemination is the deliberate introduction of sperm into a female's cervix or uterine cavity for the purpose of achieving a pregnancy through in vivo fertilization by means other than sexual intercourse. It is a fertility treatment for humans, and is a common practice in animal breeding, including dairy cattle and pigs.

Fertility is the ability to conceive a child. The fertility rate is the average number of children born during an individual's lifetime and is quantified demographically. Conversely, infertility is the difficulty or inability to reproduce naturally. In general, infertility is defined as not being able to conceive a child after one year of unprotected sex. Infertility is widespread, with fertility specialists available all over the world to assist parents and couples who experience difficulties conceiving a baby.

The Billings ovulation method is a method in which women use their vaginal mucus to determine their fertility. It does not rely on the presence of ovulation, rather it identifies patterns of potential fertility and obvious infertility within the cycle, whatever its length. Effectiveness, however, is not very clear.

Insemination is the introduction of sperm into a female's reproductive system for the purpose of impregnating, also called fertilizing, the female for sexual reproduction. The sperm is introduced into the uterus of a mammal or the oviduct of an oviparous (egg-laying) animal. In mammals, insemination normally occurs during sexual intercourse or copulation, but insemination can take place in other ways, such as by artificial insemination.

Sex selection is the attempt to control the sex of the offspring to achieve a desired sex. It can be accomplished in several ways, both pre- and post-implantation of an embryo, as well as at childbirth. It has been marketed under the title family balancing.

<span class="mw-page-title-main">Assisted reproductive technology</span> Methods to achieve pregnancy by artificial or partially artificial means

Assisted reproductive technology (ART) includes medical procedures used primarily to address infertility. This subject involves procedures such as in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI), cryopreservation of gametes or embryos, and/or the use of fertility medication. When used to address infertility, ART may also be referred to as fertility treatment. ART mainly belongs to the field of reproductive endocrinology and infertility. Some forms of ART may be used with regard to fertile couples for genetic purpose. ART may also be used in surrogacy arrangements, although not all surrogacy arrangements involve ART. The existence of sterility will not always require ART to be the first option to consider, as there are occasions when its cause is a mild disorder that can be solved with more conventional treatments or with behaviors based on promoting health and reproductive habits.

<span class="mw-page-title-main">Human reproduction</span> Procreative biological processes of humanity

Human reproduction is sexual reproduction that results in human fertilization to produce a human offspring. It typically involves sexual intercourse between a sexually mature human male and female. During sexual intercourse, the interaction between the male and female reproductive systems results in fertilization of the ovum by the sperm to form a zygote. While normal cells contain 46 chromosomes, gamete cells only contain 23 single chromosomes, and it is when these two cells merge into one zygote cell that genetic recombination occurs and the new zygote contains 23 chromosomes from each parent, giving it 46 chromosomes. The zygote then undergoes a defined development process that is known as human embryogenesis, and this starts the typical 9-month gestation period that is followed by childbirth. The fertilization of the ovum may be achieved by artificial insemination methods, which do not involve sexual intercourse. Assisted reproductive technology also exists.

Ovulation induction is the stimulation of ovulation by medication. It is usually used in the sense of stimulation of the development of ovarian follicles to reverse anovulation or oligoovulation.

The Ericsson method is an assisted reproductive technology for sex selection, used before implantation. In this method, sperm that will give rise to male versus female children are separated by moving at different speeds through a protein solution.

Semen quality is a measure of male fertility, a measure of the ability of sperm in semen to accomplish fertilization. Semen quality involves both sperm quantity and quality. Semen quality is a major factor for fertility.

Sperm sorting is a means of choosing what type of sperm cell is to fertilize the egg cell. Several conventional techniques of centrifugation or swim-up. Newly applied methods such as flow cytometry expand the possibilities of sperm sorting and new techniques of sperm sorting are being developed.

Pregnancy rate is the success rate for getting pregnant. It is the percentage of all attempts that leads to pregnancy, with attempts generally referring to menstrual cycles where insemination or any artificial equivalent is used, which may be simple artificial insemination (AI) or AI with additional in vitro fertilization (IVF).

A conception device is a medical device which is used to assist in the achievement of a pregnancy, often, but not always, by means other than sexual intercourse. This article deals exclusively with conception devices for human reproduction.

Religious response to assisted reproductive technology deals with the new challenges for traditional social and religious communities raised by modern assisted reproductive technology. Because many religious communities have strong opinions and religious legislation regarding marriage, sex and reproduction, modern fertility technology has forced religions to respond.

<span class="mw-page-title-main">Fertility testing</span>

Fertility testing is the process by which fertility is assessed, both generally and also to find the "fertile window" in the menstrual cycle. General health affects fertility, and STI testing is an important related field.

The history of in vitro fertilisation (IVF) goes back more than half a century. In 1959 the first birth in a nonhuman mammal resulting from IVF occurred, and in 1978 the world's first baby conceived by IVF was born. As medicine advanced, IVF was transformed from natural research to a stimulated clinical treatment. There have been many refinements in the IVF process, and today millions of births have occurred with the help of IVF all over the world.

<span class="mw-page-title-main">Landrum Shettles</span>

Landrum Brewer Shettles was an American obstetrician/gynecologist and a pioneer in the field of in vitro fertilization.

Mary Barton was a British obstetrician who, in the 1930s, founded one of the first fertility clinics in England to offer donor insemination. Throughout her career, Barton studied infertility and conception. Her pioneering research and practice were inspired by experience as a medical missionary in India, where she saw the harsh treatment of childless women.

Antisperm antibodies (ASA) are antibodies produced against sperm antigens.

References

  1. ↑ Shettles, Landrum B.; David M. Rorvik (October 10, 2006). How to Choose the Sex of Your Baby: Fully revised and updated (Rev Upd ed.). Broadway. p. 69. ISBN   978-0-7679-2610-2.
  2. ↑ Wilcox, A J; C R Weinberg; D D Baird (December 7, 1995). "Timing of sexual intercourse in relation to ovulation. Effects on the probability of conception, survival of the pregnancy, and sex of the baby". The New England Journal of Medicine. 333 (23): 1517–21. doi: 10.1056/NEJM199512073332301 . PMID   7477165.
  3. ↑ Harlap, Susan (June 28, 1979). "Gender of Infants Conceived on Different Days of the Menstrual Cycle". The New England Journal of Medicine. 300 (26): 1445–8. doi:10.1056/NEJM197906283002601. PMID   449885.
  4. ↑ Cui, K. H. (January 1, 1997). "Size differences between human X and Y spermatozoa and prefertilization diagnosis". Molecular Human Reproduction. 3 (1): 61–67. doi: 10.1093/molehr/3.1.61 . PMID   9239709.
  5. ↑ OBGYN, News (October 15–31, 1982). "Children of divers found to be predominantly female".{{cite journal}}: |first= has generic name (help); Cite journal requires |journal= (help)
  6. ↑ Magazine, Discover (1988). "Girls from Space".{{cite journal}}: Cite journal requires |journal= (help)
  7. ↑ Grant, Valerie (2006). "Entrenched misinformation about X and Y sperm". BMJ. 332 (7546): (7546): 916. doi:10.1136/bmj.332.7546.916-b. PMC   1440662 . PMID   16613983.
  8. ↑ Hossain, Amjad M.; Sailen Barik; Pandurang M. Kulkarni (January 2001). "Lack of Significant Morphological Differences Between Human X and Y Spermatozoa and Their Precursor Cells (Spermatids) Exposed to Different Prehybridization Treatments". Journal of Andrology. Journal of Andrology (1): 119–123). doi: 10.1002/j.1939-4640.2001.tb02161.x . PMID   11191075. S2CID   26857099.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  9. ↑ Smits, L. J. M. (2005). "Time of pregnancy and sex of offspring: a cohort study". BMJ. 331 (7530): 21437–1438. doi:10.1136/bmj.331.7530.1437. PMC   1315646 . PMID   16356978.
  10. ↑ Diasio, Robert B.; Glass, Robert H. (May 1971). "Effects of pH on the Migration of X and Y Sperm". Fertility and Sterility. 22 (5): 303–305. doi:10.1016/S0015-0282(16)38224-3. PMID   4102480.
  11. ↑ Carpinello, Olivia; DeCherney, Alan (May 2021). "Trust science?". Fertility and Sterility. 115 (5): 1196. doi: 10.1016/j.fertnstert.2021.03.001 . PMID   33823996. S2CID   233174346.
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