The aim of this PhD thesis was to produce research that could inform and benefit clinical practice by exploring the application of basic science and clinical research methodologies to disorders in obstetrics and gynaecology. Chapter 1’s investigation of endometriosis is the first to 1) report detailed genetic mapping of endometriosis-associated ovarian cancer, 2) report the existence of micro-LOH (loss of heterozygosity) in ovarian endometriosis through a SNP 100K DNA array. Chapter 2 explores the efficacy of interventions to treat menstrual abnormalities using clinical cohort studies. Furthermore, Chapter 2 highlights how negligence in female sterilization failure may be mathematically (Bayesian) modelled. Chapter 3 explores the value of systematic reviews for preventing preterm delivery and use of LNG-IUS (Mirena coil). The clinical guidelines published in Chapter 4 include: vaginal birth after previous caesarean, ectopic pregnancy, safe laparoscopic entry and minimising risk of sterilisation failure. The thesis concludes (Chapter 5) by suggesting strategies to augment the research methodological approaches evaluated in this thesis in order fulfill the aim of benefitting clinical practice. Work included in this PhD thesis has been orally presented at international conferences, published in peer-reviewed journals, and published as a national clinical guideline by the Royal College of Obstetricians and Gynaecologists, UK (RCOG).