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.
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.
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.
Combining two sperm wouldn't work. There just isn't enough in a sperm to sustain an embryo early on. What about removing the DNA from an egg, and adding two sperm to that? Theoretically you'd end up with a child with the DNA of both dads, and just a bit of the donor's DNA.
Even though only one sperm is needed for fertilization, most sperm cells will not survive the journey from the testicle to the uterus. Of the 200 million sperm deposited near the cervix in an average ejaculation, only 100,000 make it to the womb. For this reason, it's important to have a healthy sperm count when TTC.
Two mechanisms can operate to ensure that only one sperm fertilizes the egg. In many cases, a rapid depolarization of the egg plasma membrane, which is caused by the fusion of the first sperm, prevents further sperm from fusing and thereby acts as a fast primary block to polyspermy.
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.
There is a chance that two different sperm cells will fertilize both eggs. A woman gives birth to twins in this case. Fraternal twins or non-identical twins are the terms used to describe these types of twins.
Hint: Generally, two sperms do not fertilize the same egg. When one sperm comes in contact with the zona pellucida layer, there occur changes in the membrane, which prevent further entry of sperms. Two sperm fertilizing the same is very rare and occurs in very rare cases and embryos usually do not survive.
Whereas sperm quality is at the best levels between ages 30-35, motility is best before age 25. And as with semen quality, motility declines dramatically after age 55.
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.
The basis for the Shettles method starts with the fact that X-chromosome sperm (female) are on average slightly larger and thus slower moving than Y-chromosome sperm (male). And X-chromosome sperm live longer.
On an average, couples have sex 78 times from the time they start trying to the time they get a positive result. These 78 times are spread over 158 days or about 6 months. A study surveyed 1,194 parents and found that most couples have sex 13 times a month while they are trying to conceive.
How many sperm do you need to get pregnant? It takes just one sperm to fertilize a woman's egg. Keep in mind, though, for each sperm that reaches the egg, there are millions that don't. On average, each time men ejaculate they release nearly 100 million sperm.
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".
To form fraternal or dizygotic twins, two eggs (ova) are fertilised by two sperm and produce two genetically unique children.
Factors that increase the chance of twins include: consuming high amounts of dairy foods, being over the age of 30, and conceiving while breastfeeding. Many fertility drugs including Clomid, Gonal-F, and Follistim also increase the odds of a twin pregnancy.
The biological phenomenon of giving birth to twins with two different biological fathers is called heteropaternal superfecundation. In a rare and surprising event, a 19-year-old Brazilian woman gave birth to twins who belong to two different biological fathers.
Double-headed sperm are non-viable. They are unable to fertilize the egg and result in viable embryos. Thus, they are always dismissed in IVF cycles. When a sperm has two heads, the genetic material is also duplicated, which results in triploid embryos.
Fertility treatment
Some fertility drugs work by stimulating a woman's ovaries, which can sometimes cause them to release more than one egg. If sperm fertilizes both of these eggs, this can result in twins. In vitro fertilization (IVF) can also increase the chance of conceiving twins.
Studies show that the X chromosome (the girl one) carrying sperm have a longer life expectancy than the Y chromosome (the boy one), but the Y chromosome carrying sperm have better motility which means that they swim faster. There is a down side to being able to swim faster as the Y chromosomes uses more energy.
Some studies suggest that moderate ejaculation (2–4 times per week) is associated with a lower prostate cancer risk. However, ejaculating more often doesn't mean your cancer risk drops even more.
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.
Ideally, you want to have sperm ready and waiting for the egg. This is why most ovulation signs appear in the days before the egg is released. The two to four days before you ovulate are your most fertile time.