Dr Barbara Gross, B Pharm Msc PhD.,
Senior Scientific Officer,
Westmead Hospital ,
Most recently the advent of "Gender Clinics" in the UK and USA which provide gender selection based on separation of the X- and Y- bearing chromosome - female and male-sperm and artificial insemination have again raised hopes (probably false), at a considerable financial cost, for couples wishing to have a child of a particular sex
The genetic material of an embryo created through in-vitro fertilisation can now reveal the sex of a child resulting in implantation of the embryo of a desired sex said to be particularly important when there is a history of "sex-linked" disease.
Diseases such as haemophilia and Duchenne muscular dystrophy occur almost exclusively in boys.
The high cost of IVF and the low success ratio not to mention the morality of discarding unwanted embryos would prevent wide use of this technique.
In Australia some fertility clinics advise on techniques for sex selection (often at high cost) and there is a growth in non-medical advice on so called "natural" methods for increasing the chance of successfully choosing the sex of your child at the time of conception.
The preference for at least one male child has been widely reported for many developing countries e.g. in India, Nigeria and China; with the horrifying reports in some countries of abortion of the foetus of an unwanted sex or infanticide.
Recently we have read of "dying rooms" in China where female babies are left to die.
In Australia and in other countries couples express preferences about the sexual mix in their family, and it is now more common for a couple to seek to know soon after conception by amniocentesis, chorionic villi biopsy, or ultrasound, the sex of the child.
Simple advice continues to include methods relating to the timing of intercourse, of altering the acidity or alkalinity of the vagina, dietary advice, or a combination of these.
Review of Research into Timing of Intercourse
A recent review of the studies using timing of intercourse, relative to natural family planning signs and symptoms of ovulation, have failed to confirm the Shettles’ Method that intercourse around the time of ovulation would result in more male offspring.
Rather the results suggest that there is a small, but statistically significant, deficit of male births among conceptions occurring as a result of intercourse during the most fertile phase of the cycle - i.e. on the day before and on Peak Mucus Day.
The World Health Organisation Ovulation Method Study
The World Health Organisation Ovulation Method Study (1984) failed to find any significant difference in the gender of the child in relation to the conception day relative to the mucus peak.
The study revealed that 67.7% of males were conceived on the most fertile days versus 60.3% on other days of the cycle.
The New Zealand Study
This study had to be modified because of completely opposite results to what was initially predicted.
Of an initial 239 couples enrolled in the study, 148 discontinued because of a change of mind about having a pregnancy (28%), a failure to achieve a pregnancy (7%), or for reasons resulting from requirements of the study (29%).
Fifty five of 82 full term pregnancies had sufficient data for sex pre-selection analysis.
Using the peak cervical mucus day as a reference for ovulation, the study found that more male children were conceived from intercourse five days to one day before ovulation, and females from four days before to one day after ovulation, (79% were male infants compared with 38% female).
Nineteen conceptions occurred on peak day or peak plus one, 37% of these were male and 63% were female.
This is opposite to the predicted results for the Shettles method or as suggested in the Atlas of the Billings Ovulation Method, where a male child is predicted to be more likely, if intercourse is restricted to the peak day or the day following and a female child is more likely from intercourse at the beginning of the mucus phase with abstinence until the fourth day after peak.
This is an account of Dr Leonie Mc Sweeney’s prospective study of sex preselection in Nigerian women using the Billings Method.
Dr Mc Sweeney advised couples who wished to have a male child, to abstain from the onset of the mucus symptom and then to have intercourse on the morning of the second day after peak symptom day.
If conception had not occurred after several cycles, the couple were recommended to have intercourse on the night of the first day after peak, and intercourse again on the morning of the second day after peak.
She reported a male birth rate of 96.3%. A success rate of 88.9% for a female child was obtained with pre-ovulatory intercourse postponed until the appearance of the slippery mucus days prior to peak, and then abstinence until the 4th day after peak. Day 2 prior to peak appeared to be the preferable day for a female child.
These results are at variance with those of other studies on the timing of intercourse at the time of peak fertility and sex outcome. Overall, these other studies reported little difference in sex outcome compared to the usually accepted 107/100 male to female ratio.
Because of her remarkable results, an independent study needs to be repeated in other populations.
The Australian Council of Natural Family Planning does not advocate sex pre-selection methods.
This firm policy hinges upon accredited scientific research and upon ethical, medical, legal and social considerations pertaining to our Western culture.
On the other hand, in cultures where a male or female offspring is highly desirable for family and economic reasons, it could be argued that, in particular cases, a couples use of a method which appears to significantly enhance the male or female conception rate, could be justified.
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