Optimizing body weight to improve reproductive success

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Introduction: The prevalence of obesity has risen significantly in the last three decades, with the majority of adults in the developed world now being overweight, with at least one in five reproductive-age men and women being obese [1]. Since obesity is now known to reduce both male and female fertility potential, plus increase pregnancy complications and impair the health of the resulting child, it is of vital importance that all health professionals consider their patient’s weight when advising on optimal preconception care. Body mass index (BMI) is a term commonly used to quantify degrees of adiposity and is calculated as a patient’s weight in kilograms, divided by their height in meters squared. Normal (lean) BMI is between 18.5 and 24.9 kg/m2, with individuals having a BMI between 25 and 29.9 kg/m2 being considered overweight and those with a BMI of 30 kg/m2 or higher as obese. Conversely a BMI below 18.5 kg/m2 is considered underweight [1]. Throughout this chapter the terms “overweight,” “underweight,” and “obese” refer to these stated BMI ranges. The goal of this chapter is to summarize the impact of deviations from normal body weight (under- and overweight) on reproductive potential and pregnancy outcomes, while also highlighting the evidence supporting weight normalization as an effective means of improving reproductive success. Throughout these discussions we will define reproductive success beyond simple conception: rather, as the birth of a healthy child at term, conceived with the minimum of medical intervention, which then goes on to lead a healthy adult life - a worthy goal for all concerned. Impact of Obesity on Female Reproductive Potential Conception: Multiple large observational studies have conclusively linked obesity with reduced chances of natural conception or a longer time to natural conception [2-5], with some studies also reporting impaired fecundity in overweight women [3, 4]. The underlying mechanisms behind impaired fertility with increasing BMI are the net result of a combination of factors including anovulation, impaired embryo implantation, and an increased risk of miscarriage (Figure 8.1).

Original languageEnglish
Title of host publicationHow to Improve Preconception Health to Maximize IVF Success
EditorsGab Kovacs, Robert Norman
Place of PublicationUnited Kingdom
PublisherCambridge University Press
Number of pages10
ISBN (Electronic)9781316727119
ISBN (Print)9781316620731
Publication statusPublished - 1 Jan 2018


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