Daily sex (or ejaculating daily) for seven days improves men’s sperm quality by reducing the amount of DNA damage, according to an Australian study presented recently to the 25th annual meeting of the European Society of Human Reproduction and Embryology in Amsterdam. This study made headlines around the world. However, there is still no evidence that frequent ejaculation will improve the actual chances to have a baby.
It is known that a woman ovulates once during her menstrual cycle. Intercourse that occurs before or at the time of ovulation can result in pregnancy. Intercourse that occurs a day or more after ovulation will not result in pregnancy. There are three days on which intercourse produces the highest chance for pregnancy: the two days leading up to ovulation and the day of ovulation. Previous studies have indicated that if intercourse occurs within this window, then the chance for a baby is at its highest. There was no significant difference found between having intercourse every day or every other day or just once in that window.
It has not previously been studied whether intercourse or ejaculation every day for seven days prior to attempting pregnancy will improve the chance for pregnancy.
Studying Sperm Damage
To investigate this hypothesis, an Australian doctor studied 118 men who had higher than normal sperm DNA damage as indicated by a DNA Fragmentation Index (DFI). Men who had a more than 15% of their sperm (DFI >15%) damaged were eligible for the study.
The DNA Fragmentation Index (DFI) has been used as an indicator of sperm “quality”. A common test to determine the DFI is known as the sperm chromatin structure assay or SCSA. However, there is much conflicting data about whether it is a useful test to help predict male fertility. Read in detail about DFI and SCSA here: Sperm DNA Fragmentation
The men in this study had their DFI measured after abstaining from ejaculation for three days. Before they started, their DFI levels ranged between 15% and 98% DFI, with an average 34%. They were then instructed to ejaculate daily for seven days. No other treatment or lifestyle changes were suggested.
When the men’s sperm was re-assessed on the seventh day, it was found that 81% of the men had a decrease (improvement) in their DFI. The remaining 21% had an increase (worsening) in their DFI.
The study authors believe that the reason why sperm quality improved with frequent ejaculation was because the sperm had a shorter exposure in the testicular ducts and epididymis to reactive oxygen species (ROS) which are very small molecules, that can damage cellular DNA. They also hypothesized that “The remainder of the men who had an increase in DFI might have a different explanation for their sperm DNA damage.
This study received a lot of attention from the media with headlines such as “Don’t save that sperm – daily sex may improve pregnancy chances” and “Daily sex makes for healthier sperm”. As the above paragraphs illustrate, there is little evidence to back this up.
These headlines make several assumptions:
- Sperm DNA fragmentation is an accurate predictor of male fertility
- Daily sex lowers the percentage of ejaculated sperm with DNA fragmentation.
- Daily sex improves the chance for pregnancy
The first statement is uncertain at best with several studies now questioning the validity of sperm DNA fragmentation as an indicator of male fertility. The second statement may be true for the majority of men, but as this studies shows, one in five men will see higher rates of fragmentation with daily sex. The final statement is completely unsupported. This study did not look at whether the chances for pregnancy changed. It is too big a jump to automatically assume that if the DNA fragmentation index changes, that the pregnancy rate will change with it. The study authors need to do this study if they want to make this claim.