A 2015 study found that the first fraction of ejaculate contains the highest concentration sperm, and that these sperm move more effectively and are of a higher quality than those later in ejaculate.
The results showed that there were significant differences in several parameters of semen quality between first and second ejaculations. No significant differences were also found on Ca and Mg concentrations and Ca/Mg ratio. The TAC level was significantly higher in the first ejaculation than the second one.
New research run by Dr Da Li at Shengjing University suggests that sperm produced in a second ejaculation has a higher density of proteins, which speed up the sperm - making it more likely to fertilise an egg.
Summary: Sperm in the first fraction of ejaculate are more numerous, move more and present better quality DNA than those lagging behind.
The preliminary findings indicated that X spermatozoa are larger and stronger than Y spermatozoa, suggesting that they are more stable in an acidic pH than Y spermatozoa (Landrum and Shettles, 1960; Shettles, 1960).
The next time you have sex, the number of sperms is not as much as the first time, but the quality of sperm remains stable, and that quantity is enough for fertilization to occur. This proves that having sex twice in a row is still possible to get pregnant if there is no reasonable protection.
Fertility is most likely if the semen discharged in a single ejaculation (ejaculate) contains at least 15 million sperm per milliliter. Too little sperm in an ejaculation might make it more difficult to get pregnant because there are fewer candidates available to fertilize the egg.
There is ample evidence to show that as millions of human sperm cells swim towards a waiting ovum or egg, only one gets to fertilize it. Now, a new study shows that even though the fastest and most capable sperms reach the ovum first, it is the egg that has the final say on which sperm fertilizes it.
The concentration of sperm is what makes the semen cloudy and thick, so if your ejaculate is watery it is possible that you have a low sperm count. This doesn't mean you're infertile (so precautions to prevent pregnancy still need to be taken for couples that don't want to get pregnant).
It may be harder to get the rest you were able to get with your first pregnancy. There could be complications. Even if you didn't have any complications with your first birth, that doesn't mean you're guaranteed the same experience the second time around.
Unless they are deposited into a female reproductive tract, sperm cells are easily damaged and can only survive a few seconds to a few minutes outside of the body.
How much sperm does it take? In theory, a single sperm is all it takes to get pregnant. But even in a large amount of semen — such as the quantity in one ejaculation — only a fraction of the sperm are healthy, moving, and sufficiently well-formed to cause a pregnancy.
First, the zona pellucida contains sperm receptors which are specific for human sperm. Second, once the membrane has been penetrated by the sperm, it becomes impermeable to penetration by other sperm.
If the body is not properly hydrated, there may be less water in the semen, causing it to be thick or chunky. Anyone who wonders whether the thickness of their semen results from a health issue should drink plenty of water and see whether this resolves the issue.
Semen can become watery or thinner than usual if someone masturbates or engages in sexual activity multiple times each day. In this case, abstaining from sexual activity for a few days may help treat the issue. Watery semen can sometimes indicate that a person has a low sperm count or reduced semen quality.
Researchers from Stockholm University and the Manchester University NHS Foundation Trust found that the egg effectively chooses the sperm it wants, and rejects the others. "Human eggs release chemicals called chemoattractants that attract sperm to unfertilised eggs.
Human eggs use chemical signals to attract sperm. New research from Stockholm University, Manchester University NHS Foundation Trust and The University of Manchester shows that eggs use these chemical signals to “choose” sperm. Different women's eggs attract different men's sperm – and not necessarily their partners..
One explanation has to do with the chromosomes in sperm. The Y chromosome, which makes boys, contains less DNA than the X chromosome for girls. That means sperm that bear a Y chromosome swim faster in viscous liquids. Such a liquid exists at the tip of a woman's cervix in the form of a thick mucous.
Peak male fertility is around 25-29 years old. Sperm quality begins to decline at 30. At 45, men begin to experience a significant decrease in semen volume. Older men can also take longer to conceive a child.
For healthy semen samples collected between 5:00am and 7:30am were found to exhibit a statistically higher sperm concentration, total sperm count and a higher percentage of normally shaped sperm, compared to samples produced later in the day. Sperm motility was not influenced by the time of sample production.
If one egg is fertilised by two sperm, it results in three sets of chromosomes, rather than the standard two - one from the mother and two from the father. And, according to researchers, three sets of chromosomes are "typically incompatible with life and embryos do not usually survive".
Women need only wait a few seconds before the second round, with many even achieving multiple orgasms in one session. In comparison, the male refractory period varies post ejaculation, with some men ready after a few minutes and some men needing several hours to days.