Parents the world over have often wondered how to get that long-desired son or daughter who looks just like mom. In reality, determining a baby's sex is largely out of the control of both parents and left to the whims of biology. However, parents can consider fertility interventions, which may increase the odds of conceiving a baby of a particular sex.
The Father and Sex Determination
When it comes to the old-fashioned way of making babies, fathers are responsible for determining the baby's sex, according to the Novartis' Foundation's book, "The Genetics and Biology of Sex Determination." Each person has two sex chromosomes, and while women have two X chromosomes, men have an X and a Y. In conception, women contribute one of their X chromosomes, and men can contribute either an X or a Y. If the resulting embryo receives two X chromosomes, it will be female, while if it receives an X and a Y, it will be male.
Theories Involving Both Parents - Shettles Method
There are many theories on how mothers and fathers-to-be can tip the scales in favor of conceiving the daughter or son they desire. Among these is the Shettles Method, which suggests that an acidic cervix can affect the success of male Y sperm and female X sperm. Dr. Shettles theorized that Y sperm were faster but weaker than X sperm. Parents longing for a son should time intercourse close to ovulation, while parents-to-be longing for a daughter should have intercourse no more than a few days before ovulation, according to this method.
Theories on Mothers and Sex Determination
While the father contributes either an X or a Y chromosome to his future baby, some research suggests that a mother's diet could influence whether or not a particular sperm makes it to the egg. A 2000 study at Nottingham University in London suggested that vegetarian and vegan mothers were more likely to have girls, according to BBC News. In 2008, the universities of Exeter and Oxford conducted a study suggesting that mothers with higher calorie intakes were more likely to conceive boys. However, more research is necessary.
When it comes to modern technology, both parents can be responsible for determining the sex of a baby. If parents are seeking in vitro fertilization to conceive, doctors can increase the odds of conceiving a particular sex. The Ericsson method involves filtering male and female sperm and implanting the sperm for a desired sex, according to Brown Fertility Clinic in Jackson, Florida. In pre-implantation genetic diagnosis, each embryo is analyzed before implantation. If the embryos match the sex desired by the couple, they are implanted into the uterus.
- Novartis Foundation: "The Genetics and Biology of Sex Determination": 2002; John Wiley and Sons, Incorporated
- Landrum B. Shettles and David M. Rorvik: "How to Choose the Sex of Your Baby: The Method Best Supported by Scientific Evidence"; 2006; Crown Publishing Group
- Advanced Fertility Center of Chicago: IVF - In Vitro Fertilization Procedures Step by Step
- BBC News: "More Girl Babies" for Vegetarians
- BBC News: High-Calorie Diet Linked to Boys
- Brown Fertility: Baby Gender Selection
- Photo Credit Polka Dot Images/Polka Dot/Getty Images