The care of the subfertile man or woman should commence with their GP or sexual health clinic. Many subfertile couples are concerned that their diet, exercise programme or other aspects of their lifestyle may be the cause of their problem. Excessive exercise (leading to minimal body fat) may impact on fertility in women, and this may be manifest by secondary amenorrhoea. The approach to investigations revolves around the three baseline fertility parameters: sperm, eggs and tubes. Couples who fulfill the three basic fertility parameters but still don't succeed are said to have unexplained subfertility. If people work through the steps of conception, after eggs, sperm and tubes there are three other possible factors: transport, fertilization, and implantation. As it can be used to assess possible problems, or even overcome them without a diagnosis, in vitro fertilization (IVF) is indicated for the treatment of unexplained subfertility.