CNN
—

The birth of triplets, quadruplets or even more has become less common in the United States.

The rate of triplet and higher-order births in the US fell by 62% between 1998 and 2023, according to a report published Thursday by the US Centers for Disease Control and Prevention. And the biggest drops in rates were seen among mothers 30 and older.

This decline appears to be associated with how guidance has strengthened on the number of embryos transferred during the use of assisted reproductive technologies such as in vitro fertilization, known as IVF, researchers from the National Center for CDC Health Statistics.

Couples are more likely to have twinstriplets or multiple babies in one pregnancy when using assisted reproductive technology, as these fertility treatments may involve the transfer of multiple embryos into the uterus in the hope of a pregnancy.

More embryos not only increase the likelihood of a viable pregnancy, but also increase the risk that the pregnancy will involve more than one fetus – therefore twins, triplets or more.

“Monitoring trends in triplet and higher order births is important because women with a triplet/+ pregnancy are at higher risk of complications during pregnancy and their babies are at higher risk of preterm birth and infant death” , Joyce Martin, researcher at National. Center for Health Statistics and lead author of the report, said in an email.

As fertility treatments became more popular after the 1980s, there was an increase in the incidence of multiple births, said Dr. Micah Hill, president of the Society for Assisted Reproductive Technology, who was not involved in the new report.

In the early 2000s, the American Society for Reproductive Medicine and the Society for Assisted Reproductive Technology began issuing guidelines on how many embryos should be transferred in various scenarios. Guidance has been issued to help reduce the risk of complications for women undergoing fertility treatments, including the risk of premature birth.

while The new data does not indicate how many multiple births were conceived spontaneously versus through assisted reproductive technologies (ART) such as IVF, the overall decline not appear to parallel the introduction guidelines.

The guidelines were published in 2004, Hill said, and updated in 2006, 2008, 2009, 2013, 2017 and 2021.

“If you look at the CDC numbers, you can see that these declines follow every year or two after these guideline updates have occurred,” Hill said.

“These guidelines have evolved as technology has evolved,” he said. “I think it’s been successful in making fertility treatments safer, which is what we care about when we’re talking about reducing these higher order multiples.”

In part, the recommendations from latest guidelinespublished in 2021, range from recommending the transfer of a single embryo at a time for patients younger than 35 to recommending no more than four untested early-stage embryos for patients over 40.

It’s not just the guidance on embryo transfers that has changed in recent decades, possibly leading to a decrease in the number of triplets and higher-order births.

There have also been changes in the use of fetal reduction during fertility treatments, a procedure to reduce the number of fetuses when a triplet or multiple pregnancy occurs, said Dr. Amanda Williams, interim medical director for the nonprofit for the health of the mother and the infant March. de Dimes, who was not involved in the NCHS data.

Separately, she called the new NCHS report showing a decrease in triplets and higher-order multiple births “fantastic news” for maternal and infant health.

“When you have three or more babies inside, you have a significantly increased risk of preterm birth, low birth weight, infant mortality, NICU stays, and then, on the mother’s side, increased risk of gestational diabetes, increased risk of of gestational hypertension such as preeclampsia,” she said. “So this is good news for families because triplets and higher-order pregnancies are much more risky for mother and baby.”

In previous years, the rate of triplet and higher order multiple births in the United States increased from 37 of every 100,000 births in 1980 to an all-time high of about 194 births per 100,000 in 1998, according to the new report.

This “unprecedented increase” was linked to women giving birth at older ages and “increased use of fertility treatments,” Martin and her co-author Michelle Osterman wrote in the report.

“The increase was of public health concern because of the higher risk of adverse maternal and infant health outcomes in triplet and higher-order births compared with twins and singletons,” they wrote.

But since 1998, the rate of triplet and higher-order births in the United States has dropped to about 74 of every 100,000 births last year, the new data show.

Between 1998 and 2009, rates fell, but not significantly, falling 21 percent to about 154 per 100,000 births in 2009. From 2009 to 2023, rates fell significantly, by 52 percent, according to the new report, which is based on the birth certificate. data from CDC’s National Vital Statistics System. Many people may remember 2009 as the year Nadya Suleman, known in the media as Octomom, gave birth to eight children in one birth after undergoing IVF.

The new data also showed that the gross number of triplet and higher-order multiple births in the United States fell by 65 percent between 1998 and 2023 — falling from a total of 7,625 births in 1998 to 6,340 births in 2009 and , more suddenly, 2,653 births last year.

The new data “reflects what we’ve seen in fertility care” on the ground, said Dr. Asima Ahmad, an endocrinologist and fertility expert who is the medical director and co-founder of Carrot Fertility, a company that helps employers determine benefits increases. of fertility.

“Embryology labs have advanced over the years, allowing them to grow embryos further than they were able to years ago. There are also additional tests available that can provide more information about the health of the embryo,” Ahmad, who was not involved in the new NCHS report, said in an email. “Given these advances, it is becoming increasingly common for a doctor to transfer one embryo at a time to achieve the goal of a single pregnancy – the healthiest option for the pregnant person and the baby.”

Analyzing the data by maternal age, the researchers found that from 1998 to last year, triplet and higher-order multiple birth rates dropped 16 percent for mothers ages 20 to 24; 57% for mothers aged 25 to 29; 77% for mothers aged 30 to 34 and 35 to 39; and 67% for mothers 40 and older.

The researchers also found significant racial disparities.

Among white mothers, the triplet and higher-order birth rate dropped 71 percent from 1998 to last year. Triplet and higher order births to Hispanic mothers declined 25% from 1998 to 2023.

However, the triplet and higher order birth rate for black mothers followed a different trend, rising 21% from 1998 to 2009 and then not significantly changing from 2009 to 2023, resulting in an overall increase of 25% since 1998 until last year.

“The biggest declines were in white women over 30, and that’s the group that would have the most access to IVF and actual embryo transfer, where one could make the decision to transfer fewer embryos ,” said Williams of the March of Dimes. said.

But there are many other types of assisted reproductive technology that could be factors driving these racial disparities, she said.

“When you think about women of color or low-income women, they may not have access to the highest level of technology and IVF for their assisted reproductive technology,” Williams said.

“They may use less technologically advanced means of assisted reproductive technology – such as clomiphene with insemination, where you will stimulate the ovaries to produce more eggs, therefore resulting in your number of twins and triplets” , she said. “So we cannot combine assisted reproductive technology with IVF. There are less invasive, less technologically advanced forms of assisted reproductive technology that can be used by mothers of color and low-income mothers.”

Overall, the new data were “very informative,” Dr. Rachel McConnell, assistant professor of obstetrics and gynecology at Columbia University Vagelos College of Physicians and Surgeonswho was not involved in the report, said in an email.

She added that the report’s findings indicate that guidelines set by the American Society for Reproductive Medicine to transfer fewer embryos “helped reduce the number of multiple pregnancies” in IVF cycles.