Silent mutations are mutations in DNA that do not have an observable effect on the organism's phenotype. They are a specific type of neutral mutation. The phrase silent mutation is often used interchangeably with the phrase synonymous mutation; however, synonymous mutations are not always silent, nor vice versa! hope that helped :)
The placenta allows nutrients and oxygen travel from the mother to the fetus(or to the Baby. The placenta<span> is </span>fully formed<span> by 18 to 20 weeks </span>These are all I know