Sydney K. Willis

STUDY QUESTION: To what extent are self-reported diagnoses of food allergies associated with fecundability, the per-cycle probability of conception? SUMMARY ANSWER: Fecundability was not appreciably associated with self-reported food aller…

PURPOSE: To evaluate the relationships among history of asthma, asthma severity, and spontaneous abortion (SAB). METHODS: Pregnancy Study Online is a preconception cohort study of North American couples. During the preconception period, fe…

BACKGROUND: Infertility affects up to 15% of couples. In vitro fertilization (IVF) treatment has modest success rates and some factors associated with infertility and poor treatment outcomes are not modifiable. Several studies have assessed…

STUDY QUESTION: Can we derive adequate models to predict the probability of conception among couples actively trying to conceive? SUMMARY ANSWER: Leveraging data collected from female participants in a North American preconception cohort s…

STUDY QUESTION: Do daughters of older mothers have lower fecundability? SUMMARY ANSWER: In this cohort study of North American pregnancy planners, there was virtually no association between maternal age ≥35 years and daughters' fecundabili…

STUDY QUESTION: Is a history of periodontitis among women associated with reduced fecundability? SUMMARY ANSWER: A history of periodontitis, as assessed by three different self-reported measures, may be associated with reduced fecundabilit…

BACKGROUND: Caffeine, alcohol, smoking and physical activity are known to alter sex steroid synthesis, which may affect hormone-dependent gynaecologic disease risk, such as endometriosis; however, few studies have assessed life style factor…