The number of combined cases of syphilis, gonorrhea and chlamydia in the United States rose to a record high last year, including an alarming jump in the rate of newborn deaths caused by congenital syphilis, according to figures released by the Centers for Disease Control and Prevention on Tuesday.

More than 2.4 million syphilis, gonorrhea and chlamydia infections were reported in the United States in 2018, an increase of more than 100,000 cases from the previous year, the center said in its annual Sexually Transmitted Disease Surveillance Report.

It attributed the increase to several factors, including a decline in condom use among young people and men who have sex with men; increased screening among some groups; and cuts to sexual health programs at the state and local level, which led to clinic closures and fewer opportunities for counseling or testing for sexually transmitted diseases.

There were more than 115,000 syphilis cases reported to the center in 2018, a 71 percent increase since 2014. That included a 22 percent increase from 2017 in the number of newborn deaths related to congenital syphilis, which is passed from mother to child during pregnancy, the center said on Tuesday.

It said the increase in newborn deaths was a consequence of rising syphilis rates among women of reproductive age, whom it encouraged to practice safer sex and to get tested for S.T.D.s by their health care providers.

“There are tools available to prevent every case of congenital syphilis,” Gail Bolan, director of the C.D.C.’s Division of S.T.D. Prevention, said in a statement. “Testing is simple and can help women to protect their babies from syphilis — a preventable disease that can have irreversible consequences.”

There were more than 1,300 cases of syphilis cases among newborns in 2018, a 40 percent increase from the previous year, the center said. The 2018 figure represented a 185 percent increase since 2014.

It said 70 percent of congenital syphilis cases were concentrated in just five states: Texas, California, Florida, Arizona and Louisiana.

The number of gonorrhea cases last year rose 5 percent to more than 580,000, the highest number reported to the center since 1991. The number of chlamydia cases also rose by 3 percent in 2018 over the previous year to more than 1.7 million cases, the most ever reported to C.D.C., it said. The center said it had seen a surge in both infections since 2014, with gonorrhea increasing 63 percent and chlamydia increasing 19 percent since then.

Gay and bisexual men appeared to be disproportionately affected by the increase in infection rates, with men who have sex with men accounting for 54 percent of all syphilis cases in 2018, the center said.

The number of men with a diagnosis of gonorrhea has roughly doubled over the past five years, with data suggesting that gay and bisexual men were disproportionately affected by that infection as well, the center said.

The C.D.C. said its figures might not capture the true scope of the S.T.D. epidemic in the United States because many cases of chlamydia, gonorrhea and syphilis go undiagnosed and so are not reported to health authorities.

The center also said it did not receive regular reports on the spread of other sexually transmitted infections, including human papillomavirus and herpes simplex virus.

Chlamydia, gonorrhea and syphilis can all be cured by antibiotics, but if they are left untreated they can cause serious health problems, including infertility, ectopic pregnancy and an increased risk of contracting H.I.V.

In addition to a risk of infant death, congenital syphilis can also lead to miscarriage, stillbirth or, if the baby survives, to lifelong physical and neurological problems, the center said.