Gender selection is gaining increased interest and use via the IVF process. Firstly, to screen for genetic defects and secondly, to ensure the desired gender in offspring. The technique is called Preimplatation genetic diagnosis (PGD). With this process several eggs are extracted from the mother as per usual IVF procedures, sperm is supplied by the father. The eggs are fertilized in the lab and after 3 days, several 8-cell embryos should have developed. The genetic makeup of the embryos, screening for both genetic diseases and desired gender, is undertaken and ‘healthy’ embryos ,of the desired gender, are implanted in the woman. Gestation and birth take place as normal. (1) As you can imagine, there are many ethical issues being debated among the scientific community and strong concerns this is one step away from ‘designer’ babies. (2)
Our discussion here, is whether it is possible to influence the gender of offspring without the use of technology.
World Gender Ratio
The sex ratio for the entire population of the world, is 101 males to 100 females. However, gender imbalance may arise as a consequence of various factors including natural factors, exposure to pesticides and environmental contaminants, war casualties, gender-selective abortions and infanticides, aging, and deliberate gendercide. (3)
For some, sex selection can be seen as meddling with nature or even an indulgence. In reality, most people who make the effort to achieve a particular gender for their children, do so for very serious reasons. These may include the desire to avoid passing on a sex-related inherited disorder or to redress the imbalance in a family already oversupplied with one sex.
In many societies the preference for a boy is traditional and stems from reasons such as, in the upper classes, a need for an heir to carry on the family name. In lower classes (particularly agricultural societies), a need for a son is desired to help with manual work. Or simply, women often wanted sons just to please their husbands. All this stems from the patriarchal nature of most societies and even though long-held beliefs die hard, ‘mother’ nature has a way of sorting this out.
Even without our interference, there are some surprising trends in Nature’s allocation of boys to girls as set out below.
More girls tend to be born to:
- Older parents
- People who live in cooler climates
- People living in New Zealand, Australia, USA, Canada and Britain
- Parents who take Clomiphene (it thickens the cervical mucus and makes swimming to the ovum more difficult)
- Women with lower nutritional status
More boys tend to be born to:
- Parents who conceive shortly after wars (man-made disasters)
- Parents in their first 18 months of marriage
- Parents having their first child (but there is no statistical increase for either gender with subsequent children)
- Parents giving birth at certain times of the year (for example, 9 months after a national holiday, a cold snap, or an energy blackout)
- Lower paternal age (no statistical relationship to maternal age) (4)
The ABC of ‘X’ and ‘Y’
Humans have 46 chromosomes within the cell nucleus, arranged in 23 pairs. In females, the 23rd pair (the sex chromosomes) is, like the other 22, made up of two similar chromosomes. Both of these being an ‘X’, so called because of their shape. In a man’s body, the sex chromosome pair is made up of two dissimilar chromosomes, an ‘X’ and a ‘Y’. The ‘Y’ is also named due to its shape.
There are theories that because the boy foetus is formed from the uneven matching of chromosomes (XY) that it is less stable, and that the girl foetus is the ‘natural’ state!. Therefore the boy foetus has to work harder from the beginning to differentiate himself. So, this tendency of sturdy females and vulnerable males seems to continue through the life-cycle.
Each chromosome consists of two strands of the nucleic acid DNA. Arranged along these are the genes which contains all the information for the new person. The sperm has its nucleus in its head. The ovum has it’s in the centre but they only have half sets of chromosomes, 23 each. (another reason for the vulnerability of sperm to oxidative damage? The nucleus is not as well protected)
During meiosis, the full set of 23 pairs of chromosomes split. In men, this results in two different half-sets, one single set of 22 + ‘X’ and one of 22 + ‘Y’. In women, both half sets are the same, 22 + ‘X’. If the sperm carrying the ‘X’ chromosome fertilises the ovum, the two half-sets will combine to form an ‘XX’ (girl), and the ‘XY’ boy is formed by the merging of the ovum and the sperm bearing the ‘Y’ chromosome.
|Female Gametes||X||XX(baby girl)||XY(baby boy)|
|X||XX(baby girl)||XY(baby boy)|
Throughout history, there have been prescriptions for sex selection. The human desire to choose the sex of one’s offspring – to have a son rather than a daughter or a daughter rather than a son – is hardly new. In ancient Greece, it was believed that if men had sex while on their right side a boy would result. n eighteenth-century France, it was believed that if men tied off their left testicle this would result in a baby boy.
In Austria, the placenta of a female birth had to be buried under a nut tree to ensure a subsequent male baby. Lying on the right side (for both partners), was believed good for boys, with left for girls, facing north for boys, and south for girls.
Not content with dancing about in different directions, cross-dressing was also the rage in some countries. The pair swapping clothes for the night and remembering, as they tore them off, to throw them to the left (or right) of the bed. Other couples got a chance to take a young boy (or girl) to bed with them on their wedding night and the wife enjoyed a tweak of her husband’s left (or right) testicle. (5)
Who is Responsible?
Much debate through the ages has been about who is responsible, the man or the woman?
From science, we know the number of X and Y chromosomes in mammalian sperm are equal and theoretically the X and Y chromosomes have equal chance of fertilizing the ovum. This suggests there are equal number of male and female zygotes formed and that any variation at birth occurs between conception and birth. However, the studies of the effects of the gestational environment on human sex ratio is complicated, unclear and there are numerous conflicting reports. (6)
Natural Sex selection
Dr Shettles, of Columbia University’s College of Physicians and Surgeons, is a specialist in the field of reproductive physiology. Dr Shettles, whose books on sex selection is still widely drawn upon today, asserts the sex of offspring is determined by both the mother and father.
According to Dr Shettles, in most cases, the round (male) sperm, also called androsperm, outnumber the oval (female) gymnosperm. The durability of the female of the species is borne out even at this most elemental level with the female chromosome-carrying sperm being more resistant to hostile environments (such as acidic cervical mucus). Where as the male chromosome-carrying sperm are faster and more agile in favourable conditions. However, their vulnerability means that although the ‘male’ sperm start out with a considerable advantage in number, they end up only slightly ahead and live only 24 hours. Whereas the ‘female’ sperm can survive up to 3 days. It’s a case of speed vs endurance. (7)
Dr Shettles’ claims were that:
- Gynosperm (X-bearing female sperm) live longer
- Gynosperm are larger
- Gynosperm are slower
- Gynosperm are more durable
- Gynopserm are heavier
- Gynopserm are fewer in number
- Gynosperm are oval-headed
- Androsperm (Y-bearing male sperm) do not live as long
- Androsperm are smaller
- Androsperm are faster
- Androsperm are less durable
- Androsperm are lighter in weight
- Androsperm are more in number
- Androsperm are round-headed
Can Sex Selection Work?
There are many claims that an effective method of sex selection has been found and as many theories on the different qualities of ‘X’ and ‘Y’ sperm. All the claims have been refuted, revived and argued over. The only thing for sure is that the subject is controversial and there is naturally (theoretically) a 50% chance of either sex anyway. But, if they do not work, at least there are no side effects and the birth of any baby is an occasion for joy.
Was Dr Shettles right?
We still do not know for sure. Dr Shettles conducted extensive research to ‘prove’ his ideas and claims to have an 80% success rate. Plenty of other researchers have ‘disproved’ his ideas. Dr Shettles certainly came up with the most comprehensive set of ideas on the subject and most of the timing techniques described below, which rely on the proximity of intercourse and ovulation, coincide with his findings. (8)
The nuts and bolts of natural sex selection:
There are a number of things you can do to be pro-active in this matter and these are outlined below:
- Timing of intercourse: This takes advantage of the longer life span of the gynosperm and the fact, that the closer ovulation is, the more alkaline and profuse the protective mucus in the vagina, favouring the androsperm. To estimate ovulation, symptom-thermal charting is taught and used.
- Douching: This creates a more acid or alkaline environment, favouring either the more robust gynosperm (acid immobilizers the androsperm) or the speedier androsperm (in a friendly, alkaline situation). Both douches are harmless to the vagina, although repeated attempts to reduce acidity can disrupt the balance within the vaginal ecosystem.
- Position: Deep or shallow penetration is especially important at the time of ejaculation so that the sperm are either exposed to the more acidic vagina (for girls) or safely deposited at the entrance to the more alkaline cervix (for boys). Also, if there is less swimming involved for the sperm, a boy will be more likely.
- Diet: With this method, the theory is that the conditions within the reproductive tract of the female change by what is eaten before pregnancy. Two French scientists claim a 95% success rate for sex selection by placing the prospective mother on a particular diet, for at least one full month, before the conception. A diet high in sodium and potassium, for boys and calcium and magnesium, for girls. A French doctor, who has used the method extensively, claims in his book to have an 80% success rate. (9)
What does the more recent research indicate?
There are a number of studies which indicate that when maternal nutritional status is high, there is more chance of conceiving a boy. If they are low, there is more chance of conceiving a girl. Supposedly, this is due to the high maternal investment required for sons.
“Facultative (discretionary) adjustment of sex ratios by mothers occurs in some animals, and has been linked to resource availability. Humans have low fecundity (fertility), high maternal investment and a potentially high differential between the numbers of offspring produced by sons and daughters: these conditions should favour the evolution of facultative sex ratio variation. Yet little is known of natural mechanisms of sex allocation in humans. Using data from 740 British women who were unaware of their foetus’s gender, this study indicated that foetal sex is associated with maternal diet at conception. Fifty six per cent of women in the highest third of preconceptional energy intake bore boys, compared with 45% in the lowest third. Intakes during pregnancy were not associated with sex, suggesting that the foetus does not manipulate maternal diet. The results support hypotheses predicting investment in costly male offspring when resources are plentiful. Dietary changes may therefore explain the falling proportion of male births in industrialized countries. The results are relevant to the current debate about the artificial selection of offspring sex in fertility treatment and commercial ‘gender clinics’.” (10)
No matter what diet regime the mother has, her male partner does not need to follow this diet. Although, he may choose to do so, to be supportive.
The Lunar Method
Another traditional idea, is that the sign of the zodiac that the moon inhabits at the time of the conception, is a determining factor for gender. This idea was taken up by Dr Eugen Jonas, the discoverer of the lunar phase cycle and its effect on fertility, in his efforts to explore the areas of sex selection.
The earth’s magnetic field has been shown to be affected by the phases of the moon and it certainly seems that electromagnetic charge could be a factor in the separation and predominance of ‘X’ and ‘Y’ sperm. Perhaps, this is one way in which the moon might affect gender. Jonas’ claim, which complies completely with the traditional astrological viewpoint going as far back in time as the Egyptian and Alexandrian civilizations, is that when the moon is in a positive (or male) sign of the zodiac, a male child is conceived, and vice versa. Others have observed, that as the moon migrates through the signs of the zodiac, it influences the acidity or alkalinity of the female reproductive system.
When, every month, a women’s lunar phase cycle will occur, is determined at her birth by the angle of the moon, sun and earth at that time. Once every 29 .5 days (a lunar month) this angle will reoccur and this is her lunar peak. Hence, according to this theory, if the lunar peak occurs in the positive sign of the zodiac, then this favours a boy and vice versa for that particular woman. The positive (air and fire signs) and negative (water and earth signs) of the zodiac usually occur alternatively. (11)
I provide my clients with these calculations and whether each month favours a male or female conception.
In my opinion, all sex selection ideas reduce fertility to some extent. Therefore, it is only an option for couples who do not have other challenges with their fertility. In young, healthy couples who have intercourse at the fertile time of the women’s menstrual cycle have a 20% – 25% chance of conception with any particular cycle. (12) Usually, the easier conception occurs, the more likely it will be a boy. So, anyone with even slight fertility issues or older in age (more oxidative stress), will more likely have a daughter.
Even with the correct menstrual charting techniques it is difficult to accurately identify when ovulation occurs. If douching is used frequently, this may encourage an imbalance in the vaginal ecosystem. Any variation, from a healthy fertility diet to one high in sodium and potassium OR calcium and magnesium, at the expense of other nutrients,, is not advised over the long term.
Finally, there may be other factors, such as the position of the uterus as in a retroverted uterus. Here, the uterus is tilted posteriorly in contrast with a slightly ‘anteverted’ uterus, that most woman have, which is tilted forward towards the bladder. If the woman has a retroverted uterus she will usually have female conceptions because the sperm have further to swim. No degree of sex selection techniques will change this.
What happens in practice?
During the first consultation I will explain to you all the ideas and teach you to use symptom thermal charting while treating any general health issues and suggest the fertility diet. Following three months of charting you will have learnt how to interpret your charts and can estimate ovulation on the future month and use the timing techniques and any or all of the other ideas including whether the month favours female or male conception according to your lunar calculations.
In every case, the couples have had a child of their desired gender. Does that mean these techniques work? No, not necessarily, without comprehensive clinical trials which would be extremely difficult due to the complexity of factors involved. It might just be luck! But, if you want to do what you can to influence your odds, I can help.
References (all accessed 30th October 2014):
Rosvik DM and Dr Shettles. Your baby’s Sex- Now You Can Choose.
Bantam Books, NY, 1970.
Rosvik DM and Dr Shettles. Your baby’s Sex- Now You Can Choose.
Bantam Books, NY, 1970.
Dr Francois Papa and Francoise Labro. Boy or Girl.
Souvenir Press, UK, 1984.
Naish F. Natural Fertility.
Sally Milner Publishing 1991. Chapter 7 Page 95.
Sarris J, and Wardle J. Clinical naturopathy.
Churchill Livingstone 2010