Yes. You’re not imagining it. Twin births in the United States nearly doubled between 1980 and their peak in 2014, and even with a modest decline since then, the rate is still more than 60% above where it was four decades ago.
I noticed the change long before I looked into the data. After our girls were born, my twin radar went haywire. I could spot a double stroller on the far side of a parking lot before I’d noticed anything else. I assumed it was just a twin parent thing. Heightened awareness, pattern recognition, all of that. And that’s part of it. But the numbers backed me up: there are more twins now than when most of us were growing up.
The full arc of the numbers
In 1980, the twin birth rate in the United States was 18.9 per 1,000 live births, or roughly 1 in every 53 births. By 2014, it had climbed to 33.9 per 1,000, or about 1 in every 29 births. That’s an 80% increase over 34 years.
Since 2014, the rate has been slowly declining. The CDC’s most recent data puts the 2023 twin birth rate at 30.7 per 1,000, the lowest in more than 20 years, representing just over 110,000 twin births nationally. A meaningful drop from the peak, but still far above where we started.
So the full picture is a rise, a peak, and a partial reversal. Here’s what drove each.
The entire swing is in fraternal twins
If you have identical twins, this story doesn’t describe your pregnancy. None of this movement shows up in identical twin rates.
The rate of identical twinning (where a single fertilized egg splits into two) has stayed largely flat throughout this entire period, holding steady at around 4 per 1,000 births. Identical twinning is largely random. It doesn’t respond to age, family history, or fertility treatment. Whatever has been driving the national trend hasn’t touched it.
Every bit of the rise, the peak, and the decline has been in fraternal twins. Fraternal twins happen when two separate eggs are fertilized, and that process is influenced by factors that have changed significantly over the past few decades.
If you want the full biology behind it, our piece on identical vs. fraternal twins covers it in detail. The short version: the factors behind the twin boom are fraternal-specific.
Two things happened at the same time
The rise in twin births came from two forces working in parallel. They reinforced each other in a way that helps explain why the increase was so large.
Women started having babies later.
In 1980, the average age at first birth in the United States was just under 23. By the 2020s, it had climbed to more than 27, with a growing share of births happening to women in their 30s and early 40s. Age plays directly into fraternal twinning. Older women are more likely to release more than one egg in a given cycle. Your body produces more follicle-stimulating hormone (FSH) as you get older, and higher FSH can trigger more than one egg to mature and release at once. More eggs in play means a greater chance of a fraternal twin pregnancy, and it happens on its own, before any fertility treatment enters the picture.
The national data bear this out. A major analysis published in the New England Journal of Medicine found that between 1971 and 2011, the share of multiple births among women over 30 more than doubled, rising from 24% to 54%. Twins went from being primarily a younger-mother phenomenon to primarily a 30-something one.
Fertility treatment became much more common.
The other major driver was the growth of assisted reproductive technology, specifically IVF but also ovulation induction medications like Clomid that cause the ovaries to release multiple eggs. Both approaches significantly raise the odds of a fraternal twin pregnancy.
The same study estimated that by 2011, fertility treatments accounted for 36% of all twin births in the United States: roughly 17% through IVF and 19% through non-IVF ovulation induction. More than a third, tied directly to medical intervention.
The two forces were also intertwined. Older women have higher rates of infertility, which drives more of them toward fertility treatment. So delayed childbearing raised the odds of twins directly through higher FSH, and indirectly by increasing demand for treatment. The two effects stacked.
If you want to understand how age, family history, and fertility treatment each affect your own odds, our article on increasing your chances of having twins covers all of it.
The triplet story
The same pattern played out even more dramatically with triplets and higher-order multiples.
The triplet birth rate rose more than 400% between 1980 and the late 1990s. IVF clinics at the time routinely transferred multiple embryos during a single cycle to improve the odds of at least one implanting. The approach worked, but it also produced a lot of triplets, quadruplets, and higher-order pregnancies, all of which carry serious risks for both mothers and babies.
The American Society for Reproductive Medicine responded with guidelines in the late 1990s limiting the number of embryos that should be transferred. The effect was fast. The triplet rate peaked around 1998 and has been falling since. It’s come down substantially, though it hasn’t returned to pre-IVF levels.
The triplet story turned out to be a preview of what would happen to twin rates about 15 years later.
Why the rate is now falling
The twin birth rate peaked in 2014 and has declined by about 9% since. The same clinical logic that worked for triplets is now working for twins.
As IVF technology improved, success rates with single embryo transfer climbed. Better methods for freezing and thawing embryos, genetic testing before implantation, and the ability to culture embryos to the blastocyst stage. All of these made it possible to transfer one embryo at a time and still achieve strong pregnancy rates. That removed the clinical rationale for transferring two.
Twin pregnancies carry higher risks than singleton pregnancies: preterm birth, low birth weight, gestational complications. When a clinic can offer the same odds of success without those risks, most families choose that path. The shift in practice has been measurable, and the national twin rate has followed.
The rate isn’t going back to 1980 levels. Maternal age at childbearing keeps rising, and IVF remains widely used. But the peak of 2014 is almost certainly behind us.
A note for twin parents
If you have twins, you’re part of a generation that produced more of them than any before it.
Most twin pregnancies today are still conceived without fertility treatment. Even in 2011, when the share of twins linked to fertility treatment was at its measured high of about a third, two-thirds weren’t. Fraternal twins run in families through the genetics of hyperovulation. Some of what you’re seeing when you notice twins everywhere is simply that pattern playing out at scale, amplified by a generation of women having children later than their own mothers did.
The world your twins grow up in has more twins in it than the one you grew up in. Now you know why.
For more on where your own odds fit in, our article on what the chances of having twins actually are gets into the individual numbers.
Sources
Martin JA, Hamilton BE, et al. Births: Final Data for 2023. National Vital Statistics Reports, Vol. 74, No. 1. National Center for Health Statistics, 2025. https://www.ncbi.nlm.nih.gov/books/NBK618136/
Kulkarni AD, Jamieson DJ, Jones HW Jr, et al. Fertility treatments and multiple births in the United States. New England Journal of Medicine. 2013;369(23):2218–2225. https://www.nejm.org/doi/full/10.1056/NEJMoa1301467
Centers for Disease Control and Prevention, National Center for Health Statistics. FastStats: Multiple Births. https://www.cdc.gov/nchs/fastats/multiple.htm
