New York ( CNN ) -- For Luke Foreman , seeing double has always been the norm . Growing up alongside twin Megan , the California-born 16-year-old has never thought twice about the frequency of twins around him . But , late last year , Luke was surprised to learn his school could tie the world record for the most twins in the same academic year at one school . A dramatic rise in multiple-child pregnancies has left many schools with record-smashing numbers of twins and triplets . Luke Foreman 's Staples High School in Westport , Connecticut , tied the Guinness World Record this year for most sets of twins in a grade at 16 . The high school shares the title with Valley Southwoods Freshman High School in West Des Moines , Iowa . The schools , however , may not hold the record for long . Connecticut 's Greenwich High School hopes to beat the world record with 18 pair of twins in its class of 2016 . `` I was kind of stunned , '' Nancy Lanzoni , mother of twins Ben and Willy , said when she learned the Greenwich High School boasts a total 62 sets of twins in four grades . The surprising numbers reflect a rise in multiple births in the United States . `` There 's no question that the number and rate of multiple births has increased substantially in recent years , '' Joyce Martin , an epidemiologist at the National Center for Health Statistics ( NCHS ) , explains . In a report published earlier this year , the NCHS found there has been a 76 % increase in the incidence of twins from 1980 to 2009 . One in every 30 babies born in the United States in 2009 was a twin , compared to 1 in every 53 babies born in 1980 . `` The increase of triplets and higher was almost 400 % , '' Martin says . `` You do n't typically see that kind of change occurring naturally . '' The remarkable increase is largely attributed to the increasingly older age of mothers and the increased use of infertility treatments , which gained popularity in the 1980s and 1990s . `` A lot of it is driven by demographics , '' Martin explains . `` Moms tend to be older . When older women give birth naturally , they are more likely to have twins spontaneously and are more likely to have treatments . '' It comes as little surprise that two Connecticut high schools have competed for the top twin-related prize . Connecticut saw the highest twin birth rate in 2009 with nearly 5 % of all births in the state being twins . Massachusetts , New Jersey , New Hampshire and Rhode Island were not far behind . `` I 've noticed there are more twins and triplets , '' John Dodig , principal of Staples High School , says . `` I 'm sure ( our record ) will be very short lived in the Guinness World Record history . ''
Connecticut high school ties the Guinness World Record for most sets of twins in a class . Comment: Multiple births have increased due to older age of mothers , increased use of infertility therapies .