Post

Twin births have risen dramatically since the 1980s. 🧵

The share of births that are twins has risen over time. The chart shows data for France, Canada, the United States, and England & Wales in the Human Multiple Births Database.

One reason is the use of reproductive technologies such as in vitro fertilization (IVF), which make it possible for many more couples to conceive. During procedures like IVF, multiple eggs can be used at the same time to maximize the chances of a successful pregnancy, which can lead to twin births.

Another reason for the rise in twin births is that the average age of women at childbirth has risen. Older women are more likely to have twin births, even without using reproductive technologies.

You can explore the trends here, including for other countries:

Is the apparent inflection (seems to have peaked and started to come down again) IVF related, too? Multiple birth rates with IVF appear to have fallen in the 21st Century