As a sex ratio biologist, I get asked a lot of questions about how to conceive children of a particular sex. I understand the desire. I’ll admit that when I was pregnant with my kids, I was hoping for girls. And then some moms have had many of one sex and are trying to round their families out with the other.
A simple Google search on this topic brings up many methods that people say will help you to conceive the boy or girl that you want. Some of these ideas come from old wives tales, like these crazy ones:
Others come from published books that are marketed as reputable.
This topic is very close to my heart because it’s what I do my research on. I spent years writing a book on the topic, and here I’ll give you the essence of what might work and what most certainly doesn’t:
First, here’s why we might be able to “choose” a sex
Scientists have been seeing that things like war, famine and other major events can actually influence the chance of conceiving a boy! No one knows how this happens. What we do know is that when you’re trying to conceive, the man can either donate a sperm carrying an X chromosome to make a girl, or a Y chromosome to make a boy.
In 1960, Dr. Landrum Shettles viewed a sample of sperm under a microscope and saw that there were two groups of sperm, one group with with small round heads, and one group with larger oval heads. Since there were more of the small-headed sperm and there are more boys in the general population, he believed that the sperm carrying the Y chromosomes must be the ones with the small heads; small heads would allow them to swim faster than the larger X-bearing sperm.
Later research revealed that you cannot really pick out the X and Y-bearing sperm using a microscope, but there are, in fact, differences between sperm that carry and X and those that carry a Y.
These characteristics of sperm led to a virtual explosion of ideas about how we could either help along the sperm carrying a Y to increase the chances of a conceiving a boy, or hinder those Y sperm to increase the chances of having a girl. Dr. Shettles wrote the most popular book out there on the subject:
How to Choose the Sex of Your Baby: Fully revised and updated
Note that as an Amazon Associate, I may stand to benefit if you buy a product from a link in this post.
Almost all the methods that you’ll find on the web, or in the books you’ll find on Amazon, are based on the methods in this book.
But here’s the problem: many of them will actually harm your ability to concieve at all, and some can even jeopardize your health!
Here are the popular methods out there rated for safety, and the likelihood of producing the desired result:
Method 1: Timing your intercourse for a particular window
It might come as a surprise to see this one with a “do not use” ranking. Intercourse timing (often called The Shettles method) is hands down the most popular method out there for trying to control the gender you conceive. It was initially created by scientists, which makes it seem even more reputable.
But the science behind this method is not truly conclusive, and using this method could actually harm your ability to conceive at all!
Here are the basics of the method:
Your fertility for this method would then look something like this:
Why you should NOT use this method:
First, at least two other scientists have found that using this timing doesn’t work, and that you could even get the opposite results using this method!
Second, while sperm that carry the Y appear to be faster in a petrie dish, this has never been tested in the very complex environment of a woman’s reproductive system.
But here’s the worst part. We now know that only 1 in a million sperm actually makes it to the egg, and only 10% of those can be ‘activated’ to fertilize it. You have about a 20% chance of conceiving when you are actively trying and having intercourse through the week prior to ovulation. If you cut down on the number of days you’re trying, you cut your chances of success down substantially.
What’s more, doing the deed immediately before and after ovulation (as is recommended to conceive a boy) will not likely get the sperm there in time to fertilize the egg.
In essence, if using this method, it may take you years rather than months to get pregnant, all for an idea that is not truly supported by science.
Method 2: Shallow penetration to conceive a girl
This was also based on the finding that sperm carrying the Y swim faster, but don’t live as long. The idea is that if you deposit the sperm right near the cervix, the faster sperm carrying Y chromosomes will have a better shot. There’s less distance to swim, and they can out-compete the sperm carrying the X’s.
Based on this, the recommendation is to penetrate deep to conceive a boy, and shallow for a girl.
Here’s what’s wrong with this:
The journey through a woman’s vagina is not an easy one for any of the sperm. Having intercourse with purposely shallow penetration is basically like leaving a kid off miles from school with 5 minutes to spare and saying “Good luck! Hope you make it in time! And try not to die along the way”.
The sperm that carry X’s only make up a full 50% of the sperm. If you use penetration that’s too shallow, you’re purposely killing half of the sperm. That decreases your likelihood of conceiving in half!
Here’s what is ok to try:
If you vary the depth just a little (doggy style versus missionary position, for example), you may see some very very slight effects on your chance of conceiving a particular sex (like 50.1 versus 50.0%). But if this really worked, then women undergoing intrauterine insemination, where the sperm are placed directly in the uterus, would have almost all boys. Instead, you still get about 50% of each sex.
Method 3: Douching with vinegar or baking soda
This idea arose because sperm carrying the Y chromosome appear to be more fragile, which led scientists to believe that they may not survive as well in the acidic environment of the vagina.
The inside of the vagina is acidic most of the time. As ovulation approaches, the cervix releases fluids that decrease the acidity, making it easier for sperm to survive long enough to get into the uterus.
Some suggest that douching with vinegar will make the vagina so acidic that it will kill off all the Y-bearing sperm, leaving you with a girl baby. Alternatively, they say that you can boost the survival of those Y’s by douching with baking soda to make the environment more ‘friendly’ and increase your chances of conceiving a boy.
Here’s why you should never do this:
Sperm only survive at a pH between 6 and 10. Anything below 5 is considered acidic. Vinegar has a pH of around 2 – very acidic! If you douche with it, you’ve basically killed all the sperm, regardless of what sex chromosomes they’re carrying.
Baking soda solution isn’t quite as bad for the sperm. Its pH is around 8. But that’s still higher than the optimal pH of 7, and you could be introducing infection by douching with a homemade solution, and throwing off the balance of your microbial environment as well. I highly recommend that you just don’t try either of these.
Method 4: The women shouldn’t orgasm if you want a girl
This one is based on the same reasoning as the douching method. When a woman orgasms during intercourse, the muscular contractions send fluid that decreases acidity down into the vagina. As a result, the environment is much more friendly for the sperm.
Since the sperm carrying the Y are thought to be more susceptible to acidity, some suggest that you should avoid orgasming. This allows the vagina to stay more acidic, decreasing the survival of the sperm carrying Y’s.
Why this isn’t a good idea
While studies do show that your chances of conceiving increase when you orgasm, the pH of your vagina only changes minimally. This means that the fertility boost is likely because of muscular contractions that drive the sperm into the uterus, not an effect of the pH on survival of the sperm.
If you use this method, not only are you denying yourself a fun time, but you’re sacrificing a fertility benefit for an effect that has no real scientific basis.
Method 5: Changing your diet to influence the sex of your baby
OK, so this one is where you might be able to have some control. But there are so many dietary suggestions out there that are not only crazy, but could also be harmful. Here are some of the weird ones that I’ve come across:
Of all the methods out there, I have seen one that seems promising and supported by science:
- Diets high in sodium and potassium and low in magnesium and calcium led to more boys, while the opposite led to more girls. In studies testing this, they got the predicted sex over 80% of the time.
Does this mean that you should load up on the salt if you want to conceive a boy or take lots of magnesium supplements if you want a girl? Definitely no!
The researchers who conducted these studies provided very very high amounts of these to the study participants, and they were doctors that closely monitored the patients’ health. Too much salt will give you high blood pressure, and too much magnesium is toxic. Not only that, but nutrient imbalances will prevent you from getting pregnant at all.
Could you eat a few more bananas and broccoli if you’re trying to conceive a boy? Sure! It couldn’t hurt and probably would help contribute to a healthy diet. And drinking a lot of milk if you want a girl probably wouldn’t be bad, as long as you don’t chug gallons of the stuff all day long. But we still don’t know how long you would need to stick to this diet before conception.
Finally, a note on gender selection kits
There are kits on the market that cost an average of $200 and claim to guarantee the sex you want for your baby. These kits put all the methods I described above together.
- They generally include ovulation sticks and thermometers for accurately timing ovulation so you can time intercourse as described above.
- They also include douches that are acidic for conceiving a girl or basic for conceiving a boy.
- Finally, they often have supplements with the claim that they optimize the pH and ionic balance of the body.
My advice is to steer clear of these, both for the reasons discussed above, and because these supplements are not generally approved by the FDA. We don’t know what effects they might have on you or your growing baby.
What’s the take-home?
While it would be nice if there was a magic pill or a special position that would allow us to conceive the sex that we want, science tells us that we have not yet found it.
If you’re hell-bent on having a particular sex and have a couple thousand dollars to spend, you can have the sperm sorted and inserted by your local fertility clinic. With that, you can enjoy a nearly 100% success rate of getting the sex you want. Other than that, if you want to maximize your chances of conceiving, avoid most of the methods you’ll find out there on the web.
Wishing you lots of luck and baby dust!
