More women in the United States are giving birth to twins than ever before—and there are two very good reasons that might explain this new trend.
If you've been feeling like everyone around you is having twins, you might be on to something. Data from the CDC shows how common twin births are right nowand the rates associated with these births is at a record high.
Data from 2014 indicates that 33.9 out of every 1,000 births resulted in twins. While this doesn't represent a huge increase from the year before—in 2013, they observed 33.7 of every 1,000 births resulting in twins—the new number does represent a new high for America.
But while the rates of twin births are at a record high, the actual number of twins being born is lower than it's been in the past. There were 135,336 twins born in 2014 as compared to 138,961 born in 2007, the year we saw a record number of twin births. However, only 32.2 per 1,000 births were twin births that year, meaning rates for 2014 were actually higher.
These numbers aren't completely arbitrary either: There are two major factors that drive up these rates of twin births. For one thing, women are waiting until later in life to have children these days—the average age of first-time moms was at a high in 2014, clocking in at 26.4. We've all heard that fertility declines as women get older but older moms are actually more likely to give birth to fraternal twins. Ovaries start to run low on eggs as a woman ages, prompting her to release higher levels of a follicle-stimulating hormone that can cause her body to release multiple eggs.
The other factor at work is actually a surprising one. While in vitro fertilization is notorious for producing multiple births, physicians are actually encouraging women who are likely to concieve via IVF to exercise caution when transferring embryos to their uteruses. They suggest implanting no more than two embryos at a time in most cases—which means a lot of women who are conceiving after IVF treatments as having twins as opposed to triplets or higher-order multiples.
So there you have it: Two very good reasons for why you've been seeing so many pairs emerge from the delivery room.