| MULTIPLE FACTS & FIGURES 18-22% of twins are left-handed compared with under 10% for singletons Number of living multiples worldwide: 125 million Percentage of all births that are twins: 2.6% If the mother herself is a fraternal twin, she is 5 times more likely to have twins Twins have been known to develop their own dialect, or language. This is known as "cryptophasia", or "twin talk", and only they can understand what is being said. 33% of all twin births are same sex identical 33% of all twins births are Boy/Girl fraternal 33% of all twin births are same sex fraternal (These statistics include only naturally conceived multiples, not those conceived with the aid of fertility treatments, which skew the statistics in favor of fraternal twins.) Multiples occur naturally in the Caucasion population at a rate of about 1 in 100 births (66% fraternal, 34% identical). In the Asian population, twins occur in 1 out of 250 births (nearly 90% of these are identical). The African-American population can boast a whopping 1 in 50 births are fraternal twins (Identical twins in this race are rare, no one knows why, but a genetic link is suspected.) The frequency of fraternal twins can be influenced by the mother's age, race, ethnic origin or number of previous pregnancies. Identical twinning is influenced by none of these factors. The chances for fraternal twinning increase with the mother's age and peak around age 37. The greater the number of a woman's previous pregnancies, the greater the liklihood for fraternal twins. The chances of a mother of twins giving birth to twins again are one in twenty. Contrary to popular belief, twins do not necessarily skip generations. Identical twins can result from two placenta and two sacs, one placenta and two sacs, but never two placentas and one sac. Fraternal twins will never share a sac but often share a placenta. During the pregnancy, the placentas, as they enlarge, can become fused and appear as one placenta. The placenta test is extremely inaccurate in determining twin-type. Triplets can all be identical, formed from a single egg; can be formed from two eggs so that two are identical twins and the third is a fraternal sibling; or can all be fraternal, formed from three seperate eggs. The reported incidence of single-egg triplets in one out of every ten cases; two-egg triplets occur in six out of ten cases; and three-egg triplets are observed in three cases out of ten. (not counting triplets resulting from fertility treatments) |
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