Triplets are quite rare. In the United States, about 74 out of every 100,000 births are triplets or higher-order multiples, which works out to roughly 1 in every 1,350 deliveries. In 2023, just 2,505 sets of triplets were born across the entire country. And if you’re wondering about triplets conceived without any fertility assistance, those are rarer still: naturally occurring triplet pregnancies happen in roughly 1 out of every 6,000 to 8,000 births.
Triplet Rates Have Dropped Sharply Since the 1990s
Triplets are significantly less common today than they were a generation ago. Between 1998 and 2023, the triplet and higher-order birth rate fell 62%, from about 194 per 100,000 births down to 74. In raw numbers, that’s a drop from 7,625 triplet-plus births per year to 2,653.
The biggest reason for this decline is a shift in how fertility clinics operate. During the 1990s boom in assisted reproduction, doctors routinely transferred multiple embryos during IVF, which dramatically increased the chances of twins, triplets, and beyond. As the field matured, clinics moved toward transferring fewer embryos, often just one, because outcomes are better for both mother and babies. The steepest declines in triplet births happened after 2009, reflecting these newer guidelines taking hold across the industry.
Most Triplets Don’t Come From IVF
This surprises many people: IVF and other assisted reproductive technologies account for only about 13% of all triplet and higher-order births. The remaining 87% come from either natural conception or non-IVF fertility treatments like ovulation-stimulating medications, which cause the ovaries to release multiple eggs at once and carry a meaningful risk of high-order multiples.
Spontaneous triplet pregnancies, those conceived with no medical assistance at all, are the rarest category. The estimated natural incidence is about 1 in 6,000 to 8,000 births, though one large study tracking over 59,000 deliveries found a rate closer to 1 in 4,550. The variation likely reflects differences in maternal age and genetics across populations.
Age and Ethnicity Affect the Odds
Maternal age is one of the strongest predictors of a triplet pregnancy. Women 40 and older have the highest triplet birth rate of any age group, at about 179 per 100,000 births in 2022. This partly reflects biology (older women are more likely to release multiple eggs during ovulation) and partly reflects the fact that older mothers are more likely to use fertility treatments. Women under 20 have the lowest rate. Notably, the gap between age groups has narrowed considerably since the late 1990s, when mothers over 40 had a triplet rate of 518 per 100,000.
Racial and ethnic patterns in the U.S. tell a striking story. White non-Hispanic mothers saw the most dramatic decline in triplet births: a 71% drop from 1998 to 2023, falling from 263 per 100,000 births to 76. Hispanic mothers experienced a 25% decline over the same period, landing at about 57 per 100,000. Black non-Hispanic mothers, by contrast, saw a 25% increase, rising from 87 to 109 per 100,000. These differences likely reflect varying access to and use of fertility treatments, as well as demographic shifts in maternal age across groups.
How Triplets Form
Triplets can form through several biological pathways. Three separate eggs can each be fertilized by a different sperm, producing trizygotic (fully fraternal) triplets who are no more genetically similar than any siblings. Alternatively, one fertilized egg can split into identical twins while a second egg is fertilized separately, creating a mix of two identical and one fraternal sibling. In rare cases, a single egg splits twice to produce fully identical triplets.
Among naturally conceived triplets, about 80% of those developing in three separate placentas are trizygotic (all fraternal), and the rate of identical twinning within a triplet set is relatively high at 48%. In IVF-conceived triplets, the picture is very different: 96% of three-placenta triplets are fully fraternal, which makes sense given that multiple embryos are transferred as distinct individuals. Identical splitting in IVF triplets is uncommon, occurring in only about 6.5% of cases.
What a Triplet Pregnancy Looks Like
Triplet pregnancies are categorized as high-risk from the start. The average triplet delivery happens at around 33.5 weeks, roughly six and a half weeks before a typical singleton due date. About 25% of triplets arrive before 32 weeks, and 10% before 28 weeks, which places them in the very premature category with higher risks of complications.
Because of this early arrival, the majority of triplets spend time in the NICU. One large hospital study found that about 61% of triplet babies required NICU admission. For parents expecting triplets, this means planning for a likely preterm delivery, a probable cesarean section (the vast majority of triplets are delivered this way), and a NICU stay that can range from days to weeks depending on how early the babies arrive. The earlier the gestational age at birth, the longer and more intensive the NICU care tends to be.
For the mother, carrying triplets increases the risk of gestational diabetes, high blood pressure, preeclampsia, and anemia compared to singleton or even twin pregnancies. Most women carrying triplets are monitored closely starting in the second trimester, with frequent ultrasounds to track each baby’s growth and check for complications.