Other factors tied to increased autism risk, though to a lesser degree, included congenital malformations, breech and other kinds of abnormal birth positions, multiple birth, a low 5-minute Apgar score, weighing less than 5.5 pounds at birth, umbilical cord complications, fetal distress, being small for gestational age.
SILVER vs CLAD: Some of the Eisenhower Dollars issued between 1971 and 1976 were composed of 40% Silver. These were Special Issues available only from the U. S. Mint which sold them at a premium. Eisenhower Dollars issued for general circulation were Clad: composed of a mixture of nickel and copper. D (Denver): The 'D' mint mark is located on the obverse between the date and Eisenhower's neckline. S (San Francisco): The 'S' mint mark is located on the obverse between the date and Eisenhower's neckline. Note: Dollars struck in Philadelphia bear no mint mark.
To make the series more interesting, the 1979 proof set came with two very different mint mark styles â one with a filled S, better known as Type 1, and the other with a clear S, better known as Type 2. The Type 2 mint mark style was released later in the year starting with the lower denominated coins first.