In what has been called a “new normal” for American girls, premature puberty is on the rise. So is a heated debate about what causes girls to get their periods at an earlier age—and scientists have pointed the finger at plenty of culprits, like BPA, increased fat in diets and pesticides.

Now new research links another factor to early menarche: sugar-sweetened beverages. Scientists already knew that sugar-sweetened beverages could change metabolism, but they weren’t sure how they impact the timing of a developing girl’s first period. So the researchers turned to a statistical treasure trove: the Harvard Growing Up Today Study, known fondly by the acronym GUTS.

When GUTS began in 1996, the researchers who started it wanted to learn more about the effects of diet and exercise on weight. But over the years, GUTS has collected so much data on the lifestyles of thousands of children nationwide that it has been become a resource for researchers in other disciplines (and has spawned nearly 100 published papers to date).

Using GUTS data that followed 5,583 girls between nine and 14 years of age over a five-year period, scientists discovered that girls who drank more than 1.5 servings of sugar-sweetened beverages per day got their periods earlier than their counterparts—almost three months earlier. Girls who reported that level of sugar-sweetened beverage consumption were 24 percent more likely to get their period in the next month than girls who consumed less liquid sugar. And when they adjusted their results to take body mass into consideration, the likelihood that a girl drinking lots of sugar would get her period within the next month only dropped two percentage points.

You might think that caffeine or even a child’s total intake of sugar from all foods could skew the study’s results, but you’d be wrong. Researchers narrowed down the culprit to added sugar in drinks like soda, fruit juice and sweetened tea. That’s big news for scientists who have long been sounding the alarm about the dangers of soda and other sticky-sweet beverages…and important information given that earlier periods have been correlated with obesity and a higher risk for breast cancer.

Karen Michels, a Harvard Medical School professor, says that the findings could be significant for girls in developing countries, where earlier puberty is widespread. And her colleagues say that though the news is sobering, it also has a bright side—unlike other factors that play into early menarche, this is one that can be avoided by shunning sugary drinks.