1) The How And Why Of Twins -originally published in The East Honolulu Newspaper, © Kristine Bruner 1995  Have you ever wondered why some twins look exactly alike and other don't? Ever wonder why twins run in some families and not in others? The twin phenomenon is not as rare or different as you might think. Twins occur about once in every ninety live births. The exact rate differs according to geographical region and ethnic heritage. The highest rate of twinning is in the Yoruba tribe in Nigeria: about one in twenty-two. Researchers think that the abundance of yams in the Yoruba diet causes high estrogen levels in women. High estrogen levels cause more ova to mature and be released. Asian countries have the lowest twinning rate. The twinning rate in Japan, for instance, is one in every 254 births. For the most part twins and twin parents have the same problems as every one else; there are, however, circumstances and problems unique to the twin phenomenon. Two twin types are widely known. Identical twins, technically known as monozygotic, are formed from one ovum and one sperm. This one fertilized egg, for unknown reasons, splits into two identical halves which develop separately. The resulting children are almost exactly the same, physically. They will have similar foot and hand prints, but different fingerprints. Identical twins are always of the same sex. About 1/4 of identical twins are "mirror" twins -- a reflection of each other. Features, such as birthmarks, hair whorls or internal organs, appear on opposite sides of each twin. Identical twins account for about 1/3 of all twins. Researchers haven't been able to positively prove what factors influence the formation of identical twins. Fraternal twins, or dizygotic twins, are formed from two ova and two sperm. The eggs may be released from one or both ovaries. Fraternal twins can look just as similar or just as different as any two siblings would. They may or may not be the same sex. Many factors are believed to affect the occurrence of 'frats.' Studies suggest that the possibility of conceiving frats rises correspondingly with the mother's age, number of previous pregnancies, number of previous fraternal twins and amount of sexual activity. Some studies have traced this type of twinning through the mother's side. Going off birth control pills and taking fertility drugs also lead to a higher incidence of fraternal twinning. Fraternal twins can be conceived on separate occasions and even by different fathers. They can also be conceived during two different reproductive cycles, but this is rare. A third twin type is when a single egg splits and is fertilized by two sperm. Not much is known about this type. It has been difficult to research. Twin pregnancies and births have more problems than single ones. Some common problems for twins are prematurity, low birth weight and presentation in the womb (i.e. breech). Three times more twins than singletons miscarry. This includes the "vanishing twin" syndrome: twins are conceived, but only one develops and survives. The more common use of ultrasound has led to an increased identification of this syndrome -- much more than in the past. Twins can be conjoined like the famous Siamese twins, Cheng and Ang. Surgery can separate some twins that are conjoined. A problem usually associated with identical twins is the twin transfusion syndrome. One twin absorbs more nutrients and gains much more weight than its co-twin. Often one twin dies; sometimes both. Twin pregnancies have a higher incidence of stillbirths and perinatal mortality (death between the twentieth week of pregnancy through one month after birth). Mothers are more likely to develop anemia (iron deficiency) or toxemia (high blood pressure) during twin pregnancies. If you're pregnant with twins, don't panic! Most twin pregnancies end with the birth of two healthy, happy babies. Many problems can be avoided with proper prenatal care, good nutrition and regular visits to the doctor. It is even more important for mothers carrying twins to abstain from drugs, alcohol and tobacco. Doctors may go to extra lengths to ensure a successful twin pregnancy. Mothers may be restricted from travelling and even prescribed strict bed rest. In the last trimester additional doctor visits, ultrasounds and testing may be ordered. One such test, the non-stress test, checks the babies' heartbeats. Ultrasounds measure fluid levels and growth in the womb. At-home fetal monitoring may be prescribed to watch for pre-term labor which leads to prematurity. A belt with a small recording device is fastened around the mother's abdomen and worn for an hour. It records the number of contractions of the uterus -- one indicator of pre-term labor. The box is then connected to a phone and the information transmitted by modem to a computer. A nurse interprets the results and calls the mother to tell her the results. The biological aspects of having twins is just the beginning. Raising twins brings about a whole new set of social and psychological challenges for twins and parents of twins. After birth is when the fun really begins! © Kristine Bucar 1995