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    ABSTRACT: We examined the association between lifestyle factors and menstrual cycle characteristics among nulliparous Danish women aged 18-40 years who were participating in an Internet-based prospective cohort study of pregnancy planners. We used cross-sectional data collected at baseline to assess the association of age, body mass index (BMI), physical activity, alcohol and caffeine consumption, and smoking with the prevalence of irregular cycles, short (≤25 days) and long (≥33 days) cycles, and duration and amount of menstrual flow. We used log-binomial and multinomial logistic regression to estimate prevalence ratios and 95% confidence intervals. Low physical activity and heavy alcohol consumption were associated with an increased prevalence of irregular periods. High BMI, smoking, and caffeine and alcohol consumption were related to an increased prevalence of short menstrual cycles and heavy menstrual bleeding. Women in their mid-to-late thirties had shorter and lighter menstrual flow, but a lower prevalence of irregular cycles, compared with women 18-25 years of age. In this study, increased age, high BMI, and sedentary behavior were associated with menstrual-pattern irregularities. These factors may influence the balance and level of endogenous hormones conducive to optimal menstrual function.
    Clinical Epidemiology 01/2013; 5:311-9.
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    ABSTRACT: To investigate the extent to which fecundability is associated with active smoking, time since smoking cessation, and passive smoking. Prospective cohort study. Denmark, 2007-2011. A total of 3,773 female pregnancy planners aged 18-40 years. None. Self-reported pregnancy. Fecundability ratios (FRs) and 95% confidence intervals (CIs) were estimated using a proportional probabilities model that adjusted for menstrual cycle at risk and potential confounders. Among current smokers, smoking duration of ≥10 years was associated with reduced fecundability compared with never smokers (FR, 0.85, 95% CI 0.72-1.00). Former smokers who had smoked ≥10 pack-years had reduced fecundability regardless of when they quit smoking (1-1.9 years FR, 0.83, 95% CI 0.54-1.27; ≥2 years FR, 0.73, 95% CI 0.53-1.02). Among never smokers, the FRs were 1.04 (95% CI 0.89-1.21) for passive smoking in early life and 0.92 (95% CI 0.82-1.03) for passive smoking in adulthood. Among Danish pregnancy planners, cumulative exposure to active cigarette smoking was associated with delayed conception among current and former smokers. Time since smoking cessation and passive smoking were not appreciably associated with fecundability.
    Fertility and sterility 04/2014; · 3.97 Impact Factor
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    ABSTRACT: OBJECTIVE: To quantify the natural decline in fecundability by age and assess the effect of selected volitional factors. DESIGN: Prospective cohort study of women attempting conception. SETTING: Not applicable. PARTICIPANT(S): A total of 2,820 women without infertility, trying to conceive for less than 3 cycles at study entry. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Fecundability. RESULT(S): Age had little effect on fecundability except for women 35-40 years, for whom it was 0.77 relative to women aged 20-24 years. Male age showed a similar but smaller decrease, declining to 0.95 for men aged 35-39 years. The effect of age differed for parous and nulliparous women, with the latter experiencing much stronger age-related declines relative to fecundability at age 20 years. Frequency of intercourse, use of nonhormonal birth control as the last method, and timing of intercourse, each had small effects on fecundability. Women who were in the high-fecundability categories for all three of these volitional factors had an estimated probability of conceiving of 88% (95% confidence interval 83%-93%). Unlike age, these factors represent individual choices that together can offset some of the age-related decline in fecundability. CONCLUSION(S): Fecundability peaks around age 30 years, slightly earlier for nulliparous than for parous women, and then declines. The decline with age is more modest for men. Couples will experience a compounded effect of their separate age-related declines. At age 40 years, a couple's fecundability would be approximately half of what it was at age 30 years, but some of this decline can be counteracted by volitional factors affecting conception.
    Fertility and sterility 03/2013; · 3.97 Impact Factor