Record number of twin births seen around the world

Twins Emi and Mia are now five years old, but their mom, Heather Tomayasu, remembers the day she found out both were on their way, like it was yesterday.

"I went through this 10-minute cycle of cursing, laughing crying, cursing laughing crying sitting there on the table as the midwife was going, 'totally normal I hear you," she recounted of the day she was told she was having twins.

Today, Heather, who blogs on mom life on "US Japan Fam" is part of a big group of twin moms all over the world.

In fact, a recent study by Oxford University scientists found the number of twins being born globally has reached an all-time high with 1.6 million twins now being delivered each year. It found the "twinning rate" increased by a third over 40 years.

And it found two main reasons for the twin boom, which was seen in fraternal but not identical twins;  women giving birth later in life, and a rise in fertility treatments.

"Over the years we used to focus so much on getting the patient pregnant, transferring as many embryos that looked good as possible," said Dr. Brian Levine, Practice Director at CCRM Fertility New York, who explained that practice has now changed.

That's reflected in the study, which found the peak has been reached. and twin births are now leveling off, or in same cases dropping.

"Now our techniques have really improved, we're able to make very good quality embryos and because of that we feel confident to place just one back inside and have good pregnancy rates with that" said Dr. Lauren Bishop, a fertility specialist at Columbia University.

And she and other doctors. say that's a good thing.

While twins are quite adorable, they are also much riskier pregnancies.

"A twin pregnancy doesn't often go to full term, twin pregnancies are often delivered pre-term and those have a host of other consequences associated with them," said Levine.

As for Heather Tomayasu, who conceived her twins spontaneously, being a twin mom has changed her for the better and helped her find community.

"It still feels special to have twins and it's still a very special, small supportive group to be part of, and I think it will always be that way because it will never be the norm to have twins or triplets," she said.