The proud parents of daughters may long for a son, and indeed many cultures value boys above girls. In the entire human population the overall odds of naturally giving birth to either gender are about 50/50. However, factors can be tweaked in favour of a boy or a girl, depending on whether you trust statistical evidence, follow medical science or believe ‘old wives tales’. Though if old wives don’t know about giving birth, then who does?
According to the ‘Returning- Soldier Effect’, more boys are born in combative countries after major wars, perhaps nature’s way of replacing missing men. Recent research at The University of Auckland says assertive women are more likely to give birth to boys, and the project leader, Dr Valerie Grant suggests this is due to higher female testosterone levels affecting the fertilised egg. The ‘returning-soldier’ effect could be triggered by the dominant roles adopted by women when the men were at war. Their higher testosterone levels then made them more hormonally programmed to have boys.
There is also statistical evidence that you are more likely to have a boy if you carry the toxoplasmosis parasite - passed on to humans from cats – and that women who consume small amounts of arsenic, or have multiple sclerosis are more likely to have sons. So do you need to take poison, be infected by a parasite, lose your man to war or contract MS to have your longed for son?
Thankfully not! There are medical procedures to help choose the gender of your child, though some depend on where you live. In the UK, Pre-implantation Genetic Diagnosis (PGD) is only available to parents with certain gender related and genetically inherited medical conditions. In the US however, and in many countries around the world, PGD is more commonplace. After IVF (in vitro fertilisation) a cell is removed from an embryo to determine its sex, and the preferred sex is chosen for implantation. However, this is an invasive procedure and only 20% of mothers using PGD will get pregnant.
Medical science can also sort sperm to determine gender. So-called Sperm Sorting makes use of the fact that sperm bearing the Y chromosome, which produces a boy, swim faster. The Ericsson Technique chooses the fastest swimming sperm, which are then artificially inseminated into the woman. The MicroSort Method however, picks sperm according to the size of the DNA in the chromosome – the Y chromosome is smaller than the X chromosome, and has slightly less DNA.
However, if you want a more natural route to produce your son, many couples use a method introduced 20 years ago by Landrum B Shettles, MD, in his book ‘How to Choose the Sex of Your Baby’. As the Y chromosome sperm swims faster, he suggests intercourse should take place during ovulation, ie when the woman is at the peak of her fertility cycle. Quite simply, the boy, or Y carrying chromosome should get to the egg first. Some sex selection experts suggest that after sex, she should lie down for at least 20 minutes to let the Y chromosome sperm swim like a champion, and win the race to the cervix.
And of course, there are always the old wives, dispensing diet advice. For the couple in search of a bouncing baby boy, the man should drink cola or coffee before having sex, and the woman should eat salty snacks and red meat. Sleep with a blue ribbon beneath your pillow, have sex standing up, or according to Italian mamas, do it in the missionary position, to ensure that your bambino is a beautiful baby boy.