Factors Affecting Fertility

In order to take optimal care of patients who seek preconceptional counseling and of patients who present with infertility, the treating physician needs to have an extensive knowledge of the multiple factors that infl uence human reproduction. Fecundability and time to pregnancy (TTP) are used in the literature as markers of fertility. Fecundability is defi ned as the probability of conceiving in a single menstrual cycle while TTP is the length of time in months that it takes a couple to conceive. Infertility is defi ned as the failure to achieve a successful pregnancy after 12 months or more of regular unprotected intercourse in a woman under the age of 35 years and 6 months without success in a woman 35 or older. Although the current literature describes a number of factors that are likely to play a role in the ability that a patient or couple has to conceive, it is important to highlight that evidence from randomized controlled trials is lacking for the majority of these regarding quantifi cation and certainly causality of each factor. In this chapter we summarize the most relevant factors that affect fertility, making evidence based recommendations where appropriate to better counsel our patients to improve their ability to conceive. Our recommendations will include the practice committee opinions of the American Society for Reproductive Medicine (ASRM) and the American College of Obstetricians and Gynecologists (ACOG) as leading institutions in reproductive medicine and women ’ s health in the United States. Weight