Women giving birth in the U.S. are now three times more likely to have syphilis than they were in 2016, according to a report published Tuesday by the U.S. Centers for Disease Control and Prevention.The sharp rise in maternal syphilis cases has coincided with an alarming spike in congenital syphilis, or cases when a baby becomes infected before birth. In infants, syphilis can be a severe, disabling and sometimes life-threatening infection.More than 10,000 women who gave birth in 2022 had syphilis, up from about 3,400 cases in 2016, according to the CDC data. That’s about 1 maternal syphilis case for every 357 births.Another CDC report from January showed that nearly 3,800 babies were born with congenital syphilis in 2022, a 10-fold increase over the past decade and a 31% spike year-over-year; these cases caused 282 stillbirths and infant deaths in 2022.The surge in congenital syphilis is a “direct result of untested and untreated mothers,” said Dr. Irene Stafford, a maternal-fetal medicine physician with UTHealth Houston, who wasn’t involved with the new research. Syphilis “is particularly pathogenic, it’s particularly infectious to the fetus, and rates are skyrocketing.”For pregnant women who are in the early stages of a syphilis infection that is left untreated, there’s about a 70% chance that the infectious agent will pass through the placenta to the fetus, Stafford said. The risk is about the same at all stages of pregnancy and only decreases slightly during later stages of infection, she said.The vast majority of congenital syphilis cases in the U.S. – nearly 90% – might have been prevented with better testing and treatment, a recent CDC report said. Timely treatment – at least 30 days before delivery – slashes the risk that the infection will pass from mother to baby by 98%.But access to that treatment is lacking and unequal, experts say.“The overwhelming majority of pregnant patients these days are just not getting tested. And even if they do get tested, they’re not necessarily getting treated in a timely fashion,” Stafford said.Clinic hours can make it tough for pregnant women to make appointments for their care, she said. And rapid tests, which would allow diagnosis and treatment to start at the same appointment, are underutilized in favor of more nuanced tests that can take days to return results and require a follow-up visit.According to the new CDC report, maternal syphilis rates are lowest among women who start receiving prenatal care in their first trimester. They’re highest – nearly four times higher than average – among women who don’t receive any prenatal care.Maternal syphilis rates are also highest among mothers younger than 25, and they decreased with age. The rate among American Indian women who gave birth was five times higher than average, and rates among Black and Native Hawaiian women were more than double the overall rate.Clinical standards for testing women for sexually transmitted infections vary by state, Stafford said, and the new CDC data shows that maternal syphilis rates vary widely across the country. But cases are increasing nationwide; 40 states saw maternal syphilis rates more than double between 2016 and 2022.The maternal syphilis rate for 2021-22 was highest in South Dakota, one of six states where the case rate has risen more than 400% since 2016-17. The rate is lowest in Maine, one of just three states that did not have a significant increase in that time.In November, the Biden administration announced that it had established a federal task force to address the “surging syphilis epidemic.”The administration has taken some concrete steps to address the challenge, including temporarily allowing imports of an alternate medication to treats syphilis amid an ongoing shortage of the front-line treatment, but experts worry that efforts will fall short.“There’s a huge challenge before us, and there are some hopeful signs of some action,” said David Harvey, executive director of the National Coalition of STD Directors. “The bad news is that we have no indication that there are any new resources or funding being brought to the table. And no new resources means that, at the end of the day, we’re not going to succeed in bringing these rates down.”