Ignaz Semmelweis was a Hungarian physician whose work demonstrated that hand-washing could drastically reduce the number of women dying after childbirth. Until the late 1800s surgeons did not scrub up before surgery or even wash their hands between patients, causing infections to be transferred from one patient to another. Through vigorous statistical analysis, Semmelweis figured out where the problem lay and introduced rigorous hand-washing rules in the maternity ward. Deaths were drastically reduced and Semmelweis became known as the ‘saviour of the mothers’.
 
REF :  http://www.sciencemuseum.org.uk/broughttolife/people/ignazsemmelweis.aspx

A procedure in which eggs (ova) from a woman's ovary are removed. They are fertilized with sperm in a laboratory procedure, and then the fertilized egg (embryo) is returned to the woman's uterus.

The independent variable is the variable for which values are changed or selected by the investigator.

The invasion and multiplication of microorganisms such as bacteria, viruses, and parasites that are not normally present within the body

Disorders caused by organisms — such as bacteria, viruses, fungi or parasites

Energy in the region of the electromagnetic radiation spectrum at wavelengths longer than those of visible light,but shorter than those of radio waves

Interference refers to the superposing of two or more coherent waves to produce regions of maxima and minima in space, according to the principle of superposition.

The quantity between readings, eg a set of 6 readings equally spaced over a distance of 50 cm would give an interval of 10 centimetres.