ABSTRACT
More than 1 000 000 in vitro fertilization (IVF) babies have been born since Louise Brown’s birth in 1978. Several million more have resulted from less aggressive fertility treatments. These positive numbers are not without their price, however. The recent epidemic of multifetal pregnancies, more specifically the twin pregnancy rate, commonly described for decades as 1 in 90, has now doubled to more than 1 in 45. Even in the past decade, twin pregnancies continued to rise by 20%, and triplets or more by nearly 200% (Table 63.1)1. The ratio of observed to naturally expected multifetal pregnancies shows that twins are at more than double the expected rate, and quintuplets occur at almost 1000-fold over expected numbers without infertility therapies (Table 63.2). More than 70% of all twins and 99% of higher-order multiples derive from infertility treatments.
