Are Girls Getting Their Periods Earlier?

Though puberty can look different depending on the person, for girls it usually begins between ages 8-13, most commonly around 9-10 years old. Studies show that puberty is starting earlier and has dropped about three months each decade since the 1970s. Based on this newer starting age for puberty, girls in the U.S. are most likely to get their period around 12 years old.

Parents, this is your heads up that you should start talking about puberty earlier than you might have planned. Open, ongoing conversations before the changes start happening is key. And while puberty is a physiological change, there can be much more that comes with it. Your daughter will likely experience changes in emotions, relationships and her place in the world, especially among peers who may not be in the same place. Keeping the lines of communication open can help you catch any changes in behavior that may signal that your child needs some help navigating the process.

Developmental changes and when they typically happen are defined as five stages based on the Tanner Scale, which has long been considered the standard guide for medical professionals. For example, stage 1 indicates the time before any physical changes happen, and stage 2 marks the official start of puberty for girls with the first sign of breast development. A girl’s first period, which falls within stage 4 of puberty, usually happens 2-2.5 years after the breasts begin to develop.

But the timing of the stages isn’t always textbook for everyone, as researchers have found that Black and Hispanic girls tend to start puberty earlier, as do girls with a higher BMI (body mass index). A higher body fat percentage can lead the pituitary gland to activate earlier. This pea-shaped gland produces the hormones responsible for puberty. The newest data shows an obesity rate of 20.3% among ages 6-11 and 21.2% among 12–19-year-olds. And rates were higher for non-Hispanic Black girls (29.1%) and Hispanic boys (28.1%).

While obesity is widely considered a contributing cause to earlier puberty, many girls developing early are not overweight. Originally the puberty shift was a U.S. phenomenon, but things changed after a 2009 study out of Denmark, which hadn’t seen a sharp rise in childhood obesity.

Researchers found earlier breast development not explained by BMI, which pointed to other possible factors, including environmental ones. One main theory is exposure to a family of chemicals called phthalates, known as the “everywhere chemical” and found in everything from plastic food containers and toys to personal care products. But there’s still not much evidence to support a connection to these “endocrine disruptors,” which mimic estrogen.

Other factors that have been studied in connection to earlier onset puberty include stress and trauma, i.e. sexual abuse. Newer research is emerging on the effect the COVID pandemic may have had on puberty, ranging from stress, disrupted sleep cycles, increase screen time, and less activity causing rapid weight gain. But, there are many factors can influence when a girl will start her period, like your genes. It’s common to get it around the same time your mother did.

Researchers have been tracking this trend to try to get to the bottom of why it’s happening, as there have been previous studies showing potential negative effects of earlier puberty. An earlier puberty, or first period, has been associated with potential health implications including a higher risk for developing type 2 diabetes, heart disease, breast cancer or uterine cancer in adulthood. Girls who go through puberty earlier could also be at a greater risk of developing depression or anxiety.

If your daughter’s period starts on the earlier side, don’t panic or assume there’s an issue. But always talk with your child’s pediatrician with any concerns you may have.

Need help starting the conversation about puberty with your child? Check out our Girl Talk and Boys to Men classes.