Onlookers could be forgiven for doing a triple take after scores of triplets from around the world attended an annual convention.

Trios of siblings jetted in to Baltimore from as far afield as Bolivia and Puerto Rico - including one set who have become triplet models.

More than 33 families - and nearly 40 sets of triplets - attended the 2013 event held at the Holiday Inn at Inner Harbour, Baltimore, earlier this week.

Triple trouble: Nearly 40 sets of triplets pose on the stairs of the Inner Harbor Hotel in Baltimore, Maryland, where the annual Triplet Convention was held earlier this week

Three times the charm: 18-year-old Adrianna, Laurel, and Elizabeth, from Tall Timbers, Maryland,were at the event

Quadruplets - referred to as super triplets - were also invited to the event.

The attendees took part in a mass photo-shoot and workshops on how to deal with splitting up the trios at school.

Elizabeth Kamosa - who is one of three triplet sisters along with 18-year-old sisters Adrianna and Laurel - said: 'It's really fun. We do everything together. It's a unique situation.

'Everything we go through, we go through together. We share experiences with each other - and how we feel about them.

'It's a connection with another person the same age - so it's a really fun time.'

Going for a ride: Three-year-old triplets Kenya, Cadence, and Shayla, from Rockville, Maryland, in matching pink outfits

Matching: Adrianna, Laurel, and Elizabeth wore matching tops but made themselves distinguishable from each other with different coloured shorts and shoes  

Seeing triple: The identical Hernadez-Adorno triplets Gabriela, Astrid, and Myrna from Milton Freewater, Oregon

The Kamosa sisters have also capitalised on their triptych prowess and have been signed up for triplet modelling in print ads and TV commercials.

Over the years, they've attended six Triplets Conventions. Elizabeth added: 'We meet a lot of fun triplets and we usually keep in touch and try talking to each other - until we go to the next convention.

'Once we meet up, it's a happy time because we get to meet up with more triplets. You don't get to do that on a daily basis.'

Richard Blasdell, from Edgewood, Maryland, is a father to an incredible two sets of triplets.

He said: 'The second set kicked my butt because they were six years difference in age. We have problems going places because triplets are so rare. The triplets often stop traffic.'

Five sets of teenage triplets at the convention pose for a photo after going on a parade through Inner Harbour, pictured, in Baltimore

Proud parents: Jumpers with 'They're triplets. I'm glad they're mine and not yours too!' written on them were on sale at the annual Triplet Convention in Baltimore, Maryland

Parade: All the triplets at the convention took part in a parade through the streets of Inner Harbour in Baltimore holding up signs with their names on them

Dana Bishop from Santa Barbara, attended along with sisters Kelly and Lauren.

She said: 'I really like it [being a triplet] because you constantly have someone to grow up with.

'Almost everything you are going through - so are they. You always have someone who understands you - and I really like that.

'You get to meet a lot of people through it - as soon as people know you're triplets - they're going to ask you about it.'

The convention was started in 1991 by Kree Lindsey, a single mother with seven children - including a set of nine-month old triplets.

To date the largest was in 1995 when a staggering 200 sets joined together.

Easy rider: Strollers built for three were a common sight at this year's Triplet Convention in Baltimore

Sticking together: Six-year-old identical boys Granifin and Tyler, with their fraternal triplet sister, Rylie, join a parade of Triplets during the annual Triplet Convention

Kree said: 'There's just some kind of forces that causes people to meet with other people who have had the same life experiences as they've had.

'The convention is extremely successful for the emotional well-being of the triplets themselves and the parents - that's why it's is so well worth it.'

Current director of the showpiece event in the triple-sibling calendar is Kim Jones.

She was in attendance this year with her own trio of 17-year-old boys, and added: 'We are a community that comes together and have lots of fun.

'One thing people don't realise - although they are usually seen as a group, they are very much individuals.

'That's something we work hard to maintain - their individuality. It's probably not as much fun as people think, being grouped together all the time.'

Three times lucky: Fraternal Three-and-a-half year-old triplets Cristina, Brianna and Arielle Kirchhofer, from Bayside, New York, even have identical shoes

'Triplets are terrific': The triplet convention was started in 1991 by single mother Kree Lindsey who has seven children - including a set of nine-month-old triplets