The sperm in the first fraction of ejaculate are generally more fertile.
Here's why:
Sperm quality varies throughout the ejaculate. Studies have shown that the initial portion of semen typically contains a higher concentration of sperm, better motility (ability to move), and superior DNA integrity compared to the later fractions. This means the sperm released at the beginning of ejaculation have a greater chance of successfully fertilizing an egg.
Essentially, the first "round" contains the prime swimmers, increasing the odds of conception.
