In a collision of science and demographics, Massachusetts has emerged as the nation's most prolific producer of twins, triplets, and other multiple births.
The combination of an unusually large number of pregnancies in older women, who are more likely to have multiples, and a heavy reliance on readily available infertility treatments, which also increase the odds, has propelled Massachusetts to the top: The state has a twin birth rate of 4.5 for every 100 live births, compared with a national rate of 3.2, according to the most recent figures from the Centers for Disease Control and Prevention.
New Jersey and Connecticut come next, with 4.2 twins for every 100 births. Massachusetts also led the way with triplets and other multiple births.
The phenomenon has spawned a microculture in Massachusetts of support groups for parents grappling with tricky feeding schedules and such dilemmas as whether to keep twins in the same classrooms. In July, the National Organization of Mothers of Twins Clubs convenes its annual convention in Boston.
"Massachusetts is the best place to have twins," said Nicole Boloz, a teacher and mother of 5-year-old twins in Southborough. She is advertising coordinator of the West Suburban Chapter of Massachusetts Mothers of Twins Association, the state's largest with nearly 500 members. "To be in an area where there are so many other twin moms really makes a big difference. I cannot imagine not having [other twin parents] in my life."
Multiple births are spread across the state, but they tend to occur at the highest rates among parents in affluent towns west of Boston, where 5.6 of every 100 births were twins or other multiples, and on the North Shore, where 4.5 of every 100 births were multiple, according to 2006 data from the state Department of Public Health. Boston had the lowest rate, with 3.2 multiples in every 100 births.
Researchers speculate that multiple births are clustered outside of Boston because those areas tend to be homes to wealthy, highly educated women who often delay childbirth until later in life while they pursue careers. Older mothers are more likely to naturally have multiples, the researchers said, but they also tend to have greater difficulty getting pregnant and to seek assisted reproductive techniques, which by state law must be covered by insurance. They are more likely to successfully navigate the insurance and healthcare bureaucracies to receive the care, researchers said.
The high rates of multiple births in Massachusetts have presented schools with a number of challenges, such as parents' wishes to keep multiples together or apart. In Framingham, where the numbers of multiples born to residents jumped from 32 in 1996 to 50 in 2006, the schools now regularly enroll multiple sets of twins and triplets. Triplets present unique hurdles because not every elementary school has three classes per grade - a necessary component for parents who want their triplets in separate classes.
"In the past, if we had one set of triplets, it would have been something. Now we can get two or three sets - and it is interesting!" said Anna Cross, director of family support programs for the Framingham public schools.
The neonatal intensive care units at birthing hospitals have also been stressed by the trend. Multiples have a higher tendency to be born early, with twins arriving on average at 35 to 36 weeks and triplets at 33 to 34 weeks. Because of their early arrivals, the multiples often are low in weight, forcing hospitals to keep them under careful watch.
For instance, the volume at Beth Israel Deaconess Medical Center's neonatal intensive care unit has grown 23 percent in the last five years, according data provided by the hospital. Multiples disproportionately drive the expansion, accounting for 35 percent of patient days in the unit last year, according to the data. At Brigham and Women's Hospital, multiples are a "major chunk" of the neonatal intensive care unit's population, said Dr. Steven Ringer, chief of newborn medicine. The unit often balloons to 70 beds from its normal 48.
"The usual condition is one baby per uterus. That's the way the system is designed," Ringer said. "Mother nature does not take kindly to anything being unusual - even if she created it."
The costs associated with hospital stays are high, but long-term costs can be even greater. Joyce Martin, an epidemiologist at the Centers for Disease Control and Prevention, said multiples are more likely to die in their first year of life and to suffer neurological and other problems, creating costs for parents and the state, such as special education.
Concern about complications arising from multiples has prompted assisted reproductive clinicians to employ techniques that reduce the numbers of multiple births - such as implanting one embryo rather than several during in vitro fertilization.
Mark Hornstein, director of the Center for Reproductive Medicine at Brigham and Women's Hospital, said he has sought to employ the single embryo transplant method when possible because the ramifications of multiples are immense.
"Those of us who have one child at a time find it challenging," he said. "If you multiply that by two or three, I think you can imagine the stresses."