The number of triplets born in the United States reached its lowest level in 25 years, according to new data from the US Centers for Disease Control and Prevention.

After experiencing a boom in the 1980s and 1990s, rates of triplets The number of people born in the United States fell 64% between 1998 and 2023, according to new data released Thursday.

Other higher order multiple birthsincluding quadruplets, also declined over the same period, the data showed.

In 1998, there were 7,625 births of triplets, quadruplets, and higher-order multiple births in the United States, a figure that researchers believe was the result of the increasing use of fertility treatments, popularized in the 1980s.

The CDC has described the increase in multiple births as a “public health problem” because births of more than one baby carry greater health risks for the mother and babies.

By 2023, the number of births involving three or more babies had fallen to 2,505 in the United States, according to the CDC.

Researchers have attributed the decline in multiple births to changes in fertility treatments.

In recent years, the American Society for Reproductive Medicine has changed its guidelines limit the number of embryos transferred during in vitro fertilization, in an attempt to encourage singleton pregnancies.

In the IVF process, ovulation is induced and eggs are removed from the patient’s ovaries. The eggs are then fertilized with sperm outside the body, and the resulting embryos are either placed in the patient’s uterus in the hope of pregnancy or stored in a laboratory for later use. according to the American College of Obstetricians and Gynecologists.

About 2% of all infants born in the United States are conceived through the use of assisted reproductive technologies, which include IVF, according to the Department of Health and Social Services.

Although there has been an overall decline in multiple births in the United States over the past two decades, researchers have found that this decline is not equal among all races.

The rate of non-Hispanic black mothers giving birth to three or more children increased 25% between 1998 and 2023, the same period when the rate among white mothers declined 71%, according to the CDC.

Researchers have not provided an explanation for the increase in multiple births among black mothers.

ABC News Medical Unit member Dr. Harika Rayala contributed to this report.