A survey of more than 7,500 Americans aged 18 to 65, found that pubic groomers had an 80 percent higher STI risk than people who leave their nether regions hairy.
For certain infections, including herpes and chlamydia, the risk was highest among those who groomed most frequently and "intensely", the researchers found.
The study merely observed a correlation between grooming and STIs, and cannot conclude that one causes the other.
But the authors speculated that shaving or waxing may cause "microtears" in the skin, creating easy access for viruses.
Sharing tools such as razors may also be a risk, they said, citing a case of HIV transmission between brothers using the same blade.
"As a third possible explanation for our findings, individuals who groom may be more likely to engage in risky sexual behaviours than those who do not groom," said the study published in the journal Sexually Transmitted Infections.
Pubic hair grooming, it explained, "is correlated with an increased number of lifetime sexual partners and is viewed as a preparatory act to sexual engagement".
For the research, 7,580 people completed a questionnaire on their intimate hair-control, sex lives and STI history.
Seventy-four percent of respondents were pubic hair groomers -- 66 percent of men and 84 percent of women.
The trial participants were divided into "extreme groomers" who removed all pubic hair more than 11 times a year, high-frequency groomers who trimmed daily or weekly, low-frequency groomers, and non-groomers.
