Recommendations For Those Wishing To Conceive Are Changing: Sperm Does Not Need To Be "saved"

Recommendations for those wishing to conceive are changing: sperm does not need to be "saved"

Recent research, published in the journal Molecular and Cellular Proteomics, refutes the widespread belief that abstaining between pregnancy attempts improves a couple's chances of success.

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Recent research, published in the journal Molecular and Cellular Proteomics, refutes the widespread belief that abstaining between pregnancy attempts improves a couple's chances of success. A research team at the Center for Reproductive Medicine of Shengjing Hospital in Shenyang, China, worked with 500 couples to test this hypothesis.

“For many years, men were generally advised to restrict their sexual activity to increase their chances of pregnancy. But it's time to change your mind,”says one of the researchers, Dr. Da Li.

Several studies have shown that semen obtained shortly after a previous ejaculation (within about three hours) has faster and more motile sperm than abstinence for several days. But it was not clear why sperm changes, and whether these changes will affect fertility. Therefore, scientists have conducted several parallel experiments.

They examined semen both after abstinence for several days and an hour or two hours after the previous ejaculation, comparing semen volume and sperm motility. As noted earlier, sperm in semen from shorter periods of abstinence were more motile.

Using mass spectrometry to study the protein composition of the samples, the team found some major molecular differences. Most of the altered proteins were involved in cell adhesion (a function necessary for the fusion of the sperm with the egg).

Changes have been observed in proteins involved in sperm motility and metabolism, especially in proteins that regulate the formation of reactive oxygen species (a by-product of cellular energy production), the excess of which can damage the genetic material of sperm. According to the results obtained, sperm with prolonged abstinence is more vulnerable to DNA damage by active oxygen.

To find out if changes in sperm affect fertility, a study was also conducted on 500 couples preparing for in vitro fertilization in the clinic. Men in the control group donated sperm samples after several days of abstinence, while in the experimental group after three hours of abstinence.

“The typical fertility rate for a cohort of this size is about 30 percent. The experimental cohort had one-third more live births,”says Da Li.

Now scientists are advising couples with relatively normal sperm parameters to have frequent sex during ovulation. This greatly increases the likelihood of conception.

The research team plans to continue working with patients and examine the differences in post-translational modifications observed between the two types of samples. So far, this is a completely new, but very promising area.