Mortality among twins after age 6: fetal origins hypothesis versus twin method

Christensen K, Vaupel JW

1995

Denmark

8495 twin individuals born 1870-1900 were followed through to 31st December 1991. Mortality among twins and the general population was not significantly different except among females aged 60-89, in whom mortality amongst twins was 1.14 times higher than the original population. Mortality amongst female dizygotic twins was 1.77 times higher than the monozygotic twins at age 30-59. Otherwise mortality for monozygotic and dizygotic twins did not consistently differ after age 6. The authors conclude that the findings do not support the fetal origins hypothesis.

The study of twins is a way to eliminate the issue of birth order. In most studies relating an adult condition to birth size, birth order has not been taken into consideration. Yet birth order is the best known single factor influencing birth weight.