In the last 30 years, birthing multiples (twins, triplets, and quadruplets) has increased rapidly. The number of live births of multiples was 20 sets per 1,000 births. Starting in the 1980s the number of live births per 1,000 went from 20 to 35 sets (according to a recent study). The change in multiple births began to raise questions. Why were there more births of multiples? What are we doing differently?
The phenomenon of increased births of multiples has been often attributed to the increased use of modern technology that helps mothers get pregnant (such as IVF). However, doctors began to investigate the idea that the "birth of multiples" phenomenon was actually correlated to older mothers. Studies have found that older mothers have a higher chance of birthing multiples than moms who are younger than 35 years of age.
To determine whether or not the age of the mother impacted the chance of multiples, Dr. Eli Adashi (of Brown University’s Warren Alpert Medical School) and fellow researchers analyzed the Centers for Disease Control and Prevention (CDC) birth data. “Our question was: Does this social phenomenon of delayed childbearing have an impact on the incidence of multiple births in the United States?” Adashi shared. He went on to say, “in the paper, we showed that yes, indeed, not all the multiple births out there have to do with fertility drugs or in-vitro fertilization (IVF). There’s a sizable proportion of multiple births that are attributable simply to delaying childbearing. And the percentage of these spontaneous multiples seems to be growing.” Dr. Adashi made mention that the theory of increased multiple births has been around for over 100 years. However, there were little studies proving that the mother's age increased chances of birthing multiples. Now, they have the studies proving that older age really contributes to the higher probability of having multiples. In 2016, "delayed childbearing was solely responsible for 24 percent of the multiple births for white women beyond expected rates and 38 percent for black women." Dr. Adashi projected that by 2025, "women having children later without using assisted reproductive technologies could account for 46 percent of the excess multiple births for white women and 40 percent for black women."
The age at which women are having children has increased substantially. Women are choosing to have children a lot older than they were 30 years ago. Women have decided to focus on their careers, education, be married for a while, or travel the world before they "settle down" and have children. Since the age of mothers is increasing, so are the number of multiples. As the years progress, we will likely see more and more twins, triplets and quadruplets.
The study was not published to intrude on women's personal decisions to plan their families but to inform them of the risks of mothers waiting longer to have children.
Of course, waiting to have children is not a foolproof way to deliver multiples. Speak with your doctor to settle on an appropriate plan when you decide that you are ready for a baby.