Triplets:
White Americans: 1 in 8100 chance
Black Americans: 1 in 9800 chance
I believe these stats were for spontaneous conception of triplets.
Other stats I have recently seen which include spontaneous and fertility treatments:
US Triplet Rate 1989: 1 in 1445
US Triplet Rate 1995: 1 in 784
US Triplet and Higher Rate 2001: 1 per 539
In Sweden, triplets were born at a rate of about 10 per year in the 60s and 70s, which rose to 20 per year in the 80s and up to 60 in 1993. It then fell again to about 20 per year in the later 90s.
Switzerland: 1 in 3247 live births
The rate of identical triplets has stayed the same, since obviously fertility drugs do not affect their rate of conception. But the overall triplet rate has risen, making identical triplets rarer today than they were 25 or 50 years ago.
Since 1989 there have been an average of 1802 sets of triplets born each year in the US (around 150 of the sets would be identical).
http://mypage.direct.ca/c/csamson/multiples/2twinningrates.html
http://news.bbc.co.uk/1/hi/england/essex/4250997.stm (below)
Rare identical triplets go home
Ms Pierson and triplets
Linda Pierson gave birth to triplets, at odds of two million to one
Identical triplets, born to an Essex mother at odds of two million to one, have arrived home from hospital.
Brothers Stephen, Brian and Robert are extremely rare, because they are identical boys conceived naturally.
At 40, their mother Linda Pierson, of Rochford, Essex, had given up dreams of motherhood after trying unsuccessfully for years to have children.
When her "little fighters" were born at Southend Hospital in November 2004 they had a combined weight of 9lb.
The triplets were born two and a half months early and spent seven weeks in a special care unit before being allowed to go home.
30 nappies a day
"I'd always felt positive from the moment I found out I was expecting them. I knew they were all going to be okay," said Ms Pierson.
"I go through 30 nappies a day, and make up 18 bottles at least - and that's just for their milk," she added.
The triplets father, Ron Humphries, said the cost of raising the boys was going to be "astronomical" but "well worth it."
"Nobody gets a chance of having three boys together," he said.
"As long as they don't want me to play football, because by the time they're old enough to play football I don't think I'll be able to play it - but I can watch," he added. "Give them instructions."