The era of twins born at escalating rates seems to be drawing to a close.
According to the Centers for Disease Control and Prevention (CDC), twin births steadily increased for over 30 years, topping out in 2014. Now, they’re on the decline, falling about 4% and last year hitting the lowest point in a decade.
In 2014, about 1 in 29 births were twins. Now it’s down to 1 in 31 births, or 124,000 babies.
One Factor in the Decrease Is Better IVF Tech
One of the reasons for the drop in twin pregnancies is that IVF has improved over time. In earlier days of the infertility technology, doctors would improve the odds of successful implantation by using two or even three embryos at a time. This often led to multiple births, causing an increase in what could be produced simply by chance (IVF twins are always fraternal, not identical).
Now, with IVF clinics growing embryos in a lab and genetically testing them for genetic problems, doctors can pick the single, healthiest embryo rather than relying on quantity.
According to AP News, Joyce Martin, the report’s lead author, said the decrease in twin births ‘occurred only in white women and in women 30 or older. Those women are the biggest customers of expensive in vitro fertilization treatments, which are involved in roughly 15% of multiple births.”
Twin Births Are High Risk
While some parents want twins, perhaps because it’s a more cost-efficient use of IVF funds (one IVF pregnancy rather than multiple; IVF can cost upwards of $30K per round), twin births are risky.
The CDC states that “37% of IVF babies, who are multiples, are born premature, while only 3% of babies born without fertility treatments are twins, and of those about 12% are preterm.”
Some of the reasons for twins and premature birth include pregnancy complications like gestational diabetes and preeclampsia (pregnancy-related high blood pressure), which is twice as common in multiple birth scenarios. The only sure-fire “cure” for preeclampsia is delivery of the babies, even early. And early delivery usually means lower birth weights (which twins tend to have, anyway), and less lung development, which leads to time spent in the neonatal intensive care unit.
Because of these risks, the American Society of Reproductive Medicine’s recent guidelines say this:
“…women should be counseled on the risks of multiple births and embryo transfers and that this discussion should be noted in their medical records.”
According to the guidelines, “for women with reasonable medical odds of success, those under 35 should be offered single embryo transfer and no more than two at a time.”
Once a woman is over 35, the society is open to multiple embryo implantations, because, of course, a geriatric pregnancy (mother is over 35) is risky, too. However, multiple implantations add to a higher miscarriage rate, more genetic risks, and a possible long hospital stay for the babies. Not to mention the associated costs of having two babies at once, which is substantial.
None of this, of course, is to take away the pleasure and unique experience of having twins, which many parents want; it’s simply to emphasize that multiple births are riskier for both mother and babies.