The number of babies born with syphilis in the U.S. more than doubled between 2013 and 2017, according to new federal data.

Rates of congenital syphilis, which a mother passes to her baby during pregnancy or delivery, rose by more than 150% between 2013 and 2017, according to new data from the Centers for Disease Control and Prevention (CDC). A total of 918 babies were born with syphilis in 2017, the report says. That’s up from 362 in 2013 and is the highest number in 20 years. Most of these cases were clustered in Western and Southern states, with 281 in California alone.

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A woman with syphilis can be treated with antibiotics during pregnancy, but if the disease goes untreated, it can easily spread from mother to baby. While congenital syphilis can also be treated with antibiotics, it can result in permanent physical and mental health problems for an infant, and in some cases, it can even be fatal. The severity of the disease, as well as its increasing prevalence, underscores the importance of regular syphilis testing for pregnant women, the CDC says — especially given that rates of sexually transmitted diseases are at an all-time high in the U.S.

“Newborns are now paying the price for our nation’s growing STD crisis. That we have any cases of syphilis among newborns, let alone an increasing number, is a failure of the health care system,” said David Harvey, executive director of the National Coalition of STD Directors, in a statement. “It is also a symptom of the larger STD crisis in the U.S. and a sign of a public health system in urgent need of support.”

Last month, the CDC released preliminary data showing that STD rates broke records in 2017 for the fourth year in a row. Nearly 2.3 million cases of chlamydia, gonorrhea and syphilis were diagnosed in 2017, according to the CDC — about 200,000 more STDs than were diagnosed in 2016.

Write to Jamie Ducharme at jamie.ducharme@time.com.