Twins

 Twins have fascinated humankind throughout recorded history.  Often regarded as being inherently different from singleton births, societal responses have ranged from awe to fear.  The number of twins is clearly increasing, and multiple gestations (twins, triplets, etc.) now compose 3% of all births.  This recent increase is largely due to as-sisted reproductive technologies, such as in-vitro fertilization (IVF).

 Twins can be monozygotic (identical) or dizygotic (non-indentical).  With monozygotic twins, a single fertilized egg splits after conception, resulting in two indi-viduals with the same genetic composition.  When two separate eggs are fertilized dur-ing the same cycle, dizygotic twins result; these babies are as genetically distinct as any other children born to the same parents.  The frequency of monozygotic twins is fairly constant throughout the world as 4 per 1000 births.  The incidence of dizygotic twinning is influenced by race, heredity and maternal age.  Women between 35 and 40 have four times as many twins as women under 20.  In general the frequency of dizygotic twins is low in Asians, intermediate in whites and high in blacks.

 Before modern ultrasound, twins were often a surprise in the delivery room.  In fact, 50% of twins were discovered after the first twin was delivered.  Fortunately, with the modern practice of using ultrasound in most pregnancies, such surprises are rare today!

 Twin pregnancies are at higher risk for obstetric problems than are singletons and require close surveillance.  Twin pregnancies are more likely to result in maternal anemia and hypertension (toxemia).  Twins are more likely to be born prematurely and to require cesarean section.  However, with modern obstetric care, most twin pregnan-cies go well, resulting in a healthy mother with two healthy new babies.

 Fortunately, given the added expense and stress of raising two babies, twin mothers' clubs have sprung up in most metropolitan areas.  Here in St. Charles County, mothers of twins can join a group which exchanges clothing, toys and advice.  Faced with the formidable new challenge of two babies, the group helps these mothers to real-ize that they are not alone.

by Scott G. Williams, MD, FACOG, of SSM St. Charles Clinic Medical Group, O'Fallon, MO.