I sometimes hear from people who want help in gauging their chances or odds of conceiving the gender of their choice. Sometimes, they think they have special circumstances which might make their odds better or worse for what they are trying to achieve. One example of these special circumstances is the age of the father-to-be.
I heard from a woman who said “I just married a man who is middle aged. He already has grown children from a previous marriage. We would like to conceive and we are hoping for a girl. His previous children are boys. This is discouraging, but I have heard that the older a man is, the more likely he is to have a girl. Is this true, why or why not?”
This is not the first time I’ve been asked this question. This seems to be one of those old wives tales that has just enough scientific merit to make it seem believable. The thinking behind this goes something like this: since a man’s sperm count declines as he ages and there is another old wives tale which theorizes that a higher sperm count favors boy babies, then the lowered sperm count due to age must make a girl baby more likely by default.
So let’s break all these theories and old wives tales down. First, let’s look at the theory that a man’s sperm count declines with age. This one is considered true. However, such declines are usually very slight. In fact, I’m sure we all know older men that father children without any problems at all. It’s not at all rare. In fact, while there comes a point in a women’s older life when she can no longer have children due to her age, the same is not true of men.
But, accepting the fact that some men have a declining sperm counts with age, there is no definitive scientific basis to say for sure that a high sperm count favors boy babies. The thinking behind this is that because boy sperm don’t live for very long but are faster moving than girl sperm, you are going to have a better chance of conceiving a boy with a man who has a higher sperm count because the faster moving boy sperm will make it to the egg more quickly. But here’s what this theory doesn’t take into account. If a higher sperm count exists, there will be just as many girl sperm fighting for the egg. Sure, they are slower than the boys, but the ratio of X to Y or boy to girl is the same for men with high or low sperm. And the end result is usually a 50 / 50 chance of either gender. And, even if the high sperm count theory was true (which I’ve just argued that it isn’t,) this is not guarantee that the opposite would also be true.
Because according to this thinking, a lower sperm count means less X and Y sperm available. But as with the above example, the ratio would remain the same the same. And so the result (50 / 50 odds) should also remain the same. So my opinion is that no, an older man would still have roughly the same 50 / 50 chance of conceiving a girl or a boy as a younger man. This is true whether he has a high or low sperm count. Because nothing has changed with the ratio of those sperm. As long as he has roughly the same ratio of girl to boy producing sperm (which studies have shown is the norm in men of all ages) then (unless you make other changes) you still have roughly equal odds.
So what do I mean when I say “other changes?” Believe it or not, I mean changes to the woman or mother. The woman who wrote me would likely have more success trying to change her own PH than worrying about her husband, who could not change his ratios. Whether you get a girl or boy depends on whether an Y (boy producing) or X (girl producing) sperm chromosome fertilizes the egg. You can make an X or girl more likely by the woman having an acidic PH, the couple conceiving earlier in her cycle, and using shallow intercourse positions. These things would have more impact on conceiving a girl than the father’s age. If they wanted a boy, then the opposite would be true, (late intercourse, an alkaline PH, etc.) but the man already had boys and wanted a girl this time.