Meet the Clydesdale. The Clydesdale breed once almost faced extinction. Even though there is little practical use for heavy horses today because their muscle power has been replaced by machinery, breeders and enthusiasts have ensured that the breed is increasing, rather diminishing in numbers.
1 Over the three decades, the twin birth rate rose by 76 percent, from 18.9 to 33.2 per 1,000 births (or from 1.9 percent to 3.3 percent of all births) (Figure 1). 2  Increases in the twin birth rate averaged more than 2 percent a year from 1980 through 2004 (peaking at more than 4 percent from 1995 to 1998).
The risk of preterm labor and premature birth are heightened when there is more than one baby in the womb. Other conditions such as preeclampsia, placental dysfunction, and TTTS are more prevalent in twin pregnancy and increase the risk of an early delivery. Research from the National Organization of Mothers of Twins Clubs (NOMOTC) indicates that about half of multiples are born before 36 weeks gestation. An informal, unscientific poll on my site indicates 18% delivered before 28 weeks and only 15% after 38 weeks.