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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: The traditional epidemiologic modes of data collection, including paper-and-pencil questionnaires and interviews, have several limitations, such as decreasing response rates over the last decades and high costs in large study populations. The use of Web-based questionnaires may be an attractive alternative but is still scarce in epidemiologic research because of major concerns about selective nonresponse and reliability of the data obtained. The authors discuss advantages and disadvantages of Web-based questionnaires and current developments in this area. In addition, they focus on some practical issues and safety concerns involved in the application of Web-based questionnaires in epidemiologic research. They conclude that many problems related to the use of Web-based questionnaires have been solved or will most likely be solved in the near future and that this mode of data collection offers serious benefits. However, questionnaire design issues may have a major impact on response and completion rates and on reliability of the data. Theoretically, Web-based questionnaires could be considered an alternative or complementary mode in the range of epidemiologic methods of data collection. Practice and comparisons with the traditional survey techniques should reveal whether they can fulfill their expectations.
    American journal of epidemiology 09/2010; 172(11):1292-8. · 5.59 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