There are other fertility signs, known as “secondary signs” that help indicate where you are in your cycle. Generally, these are not as reliable, but can still be helpful if you have them. As ovulation nears, you may sometimes notice increased libido, tenderness in your breasts, bloating and water retention, and a normal swelling of your vaginal lips.
In addition, some lucky women have fertility signs that others of us don’t! If you have any mid-cycle spotting, it may be due to a small amount of blood that is released when ovulation occurs. The day that you ovulate is your most fertile day! Also, some women have a small amount of pain (called “mittelschmerz”) that occurs with ovulation. This pain is an indicator of peak fertility. The day you notice blood or pain is probably the best day to have sex!
Choosing Your Baby’s Sex
First, a couple of disclaimers. The only way to be 100% sure that you will have a baby of a certain sex involves high-tech, expensive medical implantation techniques, which are out of the question for most of us (especially if we do not have problems with infertility). Also, if you are already pregnant, you can no longer choose your baby’s sex! It was decided at conception. That being said, the following is the most scientifically plausible theory for selecting the sex of your child at that critical moment.
As you may know, every person has two sex chromosomes. Males have an X chromosome (named thusly because it is shaped like an X) and a Y chromosome (shaped like a Y). Females have two X chromosomes. The egg cell from a woman always contains an X chromosome (because women have no Y chromosomes). On the other hand, half of sperm cells contain an X chromosome, and half contain a Y. If an X sperm unites with the egg, the result is XX, a girl. If a Y chromosome meets the egg instead, the result is XY, a boy.
X chromosomes (like the letter X) are larger than Y chromosomes (like the letter Y), because they have one additional projection. For this reason, sperm cells containing X chromosomes are heavier. Being heavier, they may travel to the egg more slowly than sperm cells bearing Y chromosomes. If it were merely a contest of speed, the lightweight Y sperm cells would win every time, and most all babies would be boys. This is obviously not the case. The X-bearing sperm also have an advantage. They are more stable than the Y sperm, and they can live longer. So, if the contest is longevity, X sperm will certainly win.
To apply this theory, it makes sense that having sex closest to ovulation, that moment of peak fertility, is advantageous to Y sperm. They swim fastest and can make it to the egg first, producing XY offspring (a boy). On the other hand, having sex farthest from the time of ovulation (but still within the fertile period) is advantageous to X sperm. They can wait longer, remaining alive in the female reproductive tract while the fragile Y sperm die. This leads to XX offspring (a girl).