To investigate the extent to which fecundability is associated with active smoking, time since smoking cessation, and passive smoking.
Prospective cohort study.
A total of 3,773 female pregnancy planners aged 18-40 years.
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.
To investigate to what extent alcohol consumption affects female fecundability.
Prospective cohort study.
Denmark, 1 June 2007 to 5 January 2016.
6120 female Danish residents, aged 21-45 years, in a stable relationship with a male partner, who were trying to conceive and not receiving fertility treatment.
Alcohol consumption was self reported as beer (330 mL bottles), red or white wine (120 mL glasses), dessert wine (50 mL glasses), and spirits (20 mL) and categorized in standard servings per week (none, 1-3, 4-7, 8-13, and =14). Participants contributed menstrual cycles at risk until the report of pregnancy, start of fertility treatment, loss to follow-up, or end of observation (maximum 12 menstrual cycles). A proportional probability regression model was used to estimate fecundability ratios (cycle specific probability of conception among exposed women divided by that among unexposed women).
4210 (69%) participants achieved a pregnancy during follow-up. Median alcohol intake was 2.0 (interquartile range 0-3.5) servings per week. Compared with no alcohol consumption, the adjusted fecundability ratios for alcohol consumption of 1-3, 4-7, 8-13, and 14 or more servings per week were 0.97 (95% confidence interval 0.91 to 1.03), 1.01 (0.93 to 1.10), 1.01 (0.87 to 1.16) and 0.82 (0.60 to 1.12), respectively. Compared with no alcohol intake, the adjusted fecundability ratios for women who consumed only wine (=3 servings), beer (=3 servings), or spirits (=2 servings) were 1.05 (0.91 to1.21), 0.92 (0.65 to 1.29), and 0.85 (0.61 to 1.17), respectively. The data did not distinguish between regular and binge drinking, which may be important if large amounts of alcohol are consumed during the fertile window.
Consumption of less than 14 servings of alcohol per week seemed to have no discernible effect on fertility. No appreciable difference in fecundability was observed by level of consumption of beer and wine.
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BACKGROUND: Recent studies have shown that both female and male obesity may delay time-to-pregnancy (TTP). Little is known about central adiposity or weight gain and fecundability in women. METHODS: We examined the association between anthropometric factors and TTP among 1651 Danish women participating in an internet-based prospective cohort study of pregnancy planners (2007-2008). We categorized body mass index (BMI = kg/m(2)) as underweight ( or =35). We used discrete-time Cox regression to estimate fecundability ratios (FRs) and 95% confidence intervals (CI), controlling for potential confounders. RESULTS: We found longer TTPs for overweight (FR = 0.83, 95% CI = 0.70-1.00), obese (FR = 0.75, 95% CI = 0.58-0.97), and very obese (FR = 0.61, 95% CI = 0.42-0.88) women, compared with normal weight women. After further control for waist circumference, FRs for overweight, obese, and very obese women were 0.72 (95% CI = 0.58-0.90), 0.60 (95% CI = 0.42-0.85) and 0.48 (95% CI = 0.31-0.74), respectively. Underweight was associated with reduced fecundability among nulliparous women (FR = 0.82, 95% CI = 0.63-1.06) and increased fecundability among parous women (FR = 1.61, 95% CI = 1.08-2.39). Male BMI was not materially associated with TTP after control for female BMI. Compared with women who maintained a stable weight since age 17 (-5 to 4 kg), women who gained > or =15 kg had longer TTPs (FR = 0.72, 95% CI = 0.59-0.88) after adjustment for BMI at age 17. Associations of waist circumference and waist-to-hip ratio with TTP depended on adjustment for female BMI: null associations were observed before adjustment for BMI and weakly positive associations were observed after adjustment for BMI. CONCLUSIONS: Our results confirm previous studies showing reduced fertility in overweight and obese women. The association between underweight and fecundability varied by parity.
BACKGROUND: A depressed Apgar score at 5 minutes is a marker for perinatal insults, including neurologic damage. We examined the association between 5-minute Apgar score and the risk of epilepsy hospitalization in childhood. METHODS: Using records linked from population registries, we conducted a cohort study among singleton children born alive in the period 1978-2001 in North Jutland County, Denmark. The first hospital discharge diagnosis of epilepsy during the follow-up time was the main outcome. We followed each child for up to 12 years, calculated absolute risks and risk differences, and used a Poisson regression model to estimate risk ratios for epilepsy hospitalization. We adjusted risk ratio estimates for birth weight, gestational age, mode of delivery, birth presentation, mother's age at delivery, and birth defects. RESULTS: One percent of the 131,853 eligible newborns had a 5-minute Apgar score
Earlier studies suggest a protective association between vitamin K antagonist (VKA) anticoagulants and the incidence of cancer. The authors examined the associations between VKA therapy and incidence of 24 site-specific cancers with a Danish population-based cohort study, using heart valve replacement as an instrumental variable. The authors enrolled 9,727 Danish residents who received a replacement heart valve between 1989 and 2006. The heart valve recipients were matched with 95,481 unexposed individuals on age and sex. The authors used the heart valve replacement instrument to estimate rate ratios associating VKA therapy with incidence of the 24 site-specific cancers using Poisson regression models. Direct associations between VKA therapy and incidence of the 24 cancers were estimated in a prescription validation subset. The instrumental variable associations were plotted according to the inverse normal of rank percentile and subjected to semi-Bayes shrinkage adjustment for multiple comparisons. The pattern of associations was consistent with a null-centered Gaussian distribution. No individual cancer site showed a substantial positive or negative association with VKA therapy in the prescription validation subset, the instrumental variable analysis, or the analysis with semi-Bayes adjustment. These results do not support the existing hypothesis that VKA therapy is associated with reduced cancer risk.
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Apgar score is used for rapid assessment of newborns. Low five-minute Apgar score has been associated with increased risk of severe neurologic outcome, but data on milder outcomes, particularly in the long term, are limited. We aimed to examine the association of five-minute Apgar score with prevalence of neurologic disability and with cognitive function in early adulthood.
We conducted a prevalence study among draft-liable men born in Denmark in 1978-1983 and presenting for the mandatory army evaluation in a northern Danish conscription district. We linked records of this evaluation, which includes medical exam and intelligence testing, with the conscripts' records in the Medical Birth Registry, containing perinatal data. We examined prevalence of neurologic disability and of low cognitive function according to five-minute Apgar score.
Less than 1% (136/19,559) of the conscripts had 5-minute Apgar scores
Animal studies have shown that a high intake of galactose, a breakdown product of lactose, increases ovarian toxicity. Few epidemiologic studies, to our knowledge, have examined the association between dairy intake and fertility, and they have had conflicting findings.
We prospectively evaluated dairy intake in relation to fecundability among women who were planning for pregnancy.
Data were derived from preconception cohort studies in Denmark (Snart Foraeldre) and North America [PRESTO (Pregnancy Study Online)] in which women completed a validated food-frequency questionnaire 10 d after enrollment. The dietary intake of dairy foods and their constituents was calculated based on reported frequencies, mean serving sizes, and standard recipes for mixed foods. Outcome data were updated every 8 wk for 12 mo or until reported conception. Analyses were restricted to 2426 women attempting pregnancy for =6 cycles at study entry. Fecundability ratios (FRs) and 95% CIs were estimated with the use of proportional probabilities regression models adjusted for potential confounders.
We launched the Boston University Pregnancy Study Online (PRESTO) to assess the feasibility of carrying out an Internet-based preconception cohort study in the US and Canada.
We recruited female participants age 21-45 and their male partners through Internet advertisements, word of mouth, and flyers. Female participants were randomised with 50% probability to receive a subscription to FertilityFriend.com (FF), a web-based programme that collects real-time data on menstrual characteristics. We compared recruitment methods within PRESTO, assessed the cost-efficiency of PRESTO relative to its Danish counterpart (Snart-Gravid), and validated retrospectively reported date of last menstrual period (LMP) against the FF data.
After 99 weeks of recruitment (2013-15), 2421 women enrolled; 1384 (57%) invited their male partners to participate, of whom 693 (50%) enrolled. Baseline characteristics were balanced across randomisation groups. Cohort retention was similar among those randomised vs. not randomised to FF (84% vs. 81%). At study enrollment, 56%, 22%, and 22% couples had been trying to conceive for 97% reported their LMP on the PRESTO questionnaire within 1 day of the LMP recorded via FF.
Use of the Internet as a method of recruitment and follow-up in a North American preconception cohort study was feasible and cost-effective.
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To our knowledge, no previous study has examined functioning in adult life among persons who had bacterial meningitis in childhood.
To study educational achievement and economic self-sufficiency in adults diagnosed as having bacterial meningitis in childhood.
Nationwide population-based cohort study using national registries of Danish-born children diagnosed as having meningococcal, pneumococcal, or Haemophilus influenzae meningitis in the period 1977-2007 (n=2784 patients). Comparison cohorts from the same population individually matched on age and sex were identified, as were siblings of all study participants. End of study period was 2010.
Cumulative incidences of completed vocational education, high school education, higher education, time to first full year of economic self-sufficiency, and receipt of disability pension and differences in these outcomes at age 35 years among meningitis patients, comparison cohorts, and siblings.
By age 35 years, among persons who had a history of childhood meningococcal (n=1338), pneumococcal (n=455), and H. influenzae (n=991) meningitis, an estimated 11.0% (41.5% vs 52.5%; 95% CI, 7.3%-14.7%), 10.2% (42.6% vs 52.8%; 95% CI, 3.8%-16.6%), and 5.5% (47.7% vs 53.2%; 95% CI, 1.9%-9.1%) fewer persons, respectively, had completed high school and 7.9% (29.3% vs 37.2%; 95% CI, 1.6%-14.2%), 8.9% (28.1% vs 37.0%; 95% CI, 0.6%-17.2%), and 6.5% (33.5% vs 40.0%; 95% CI, 1.4%-11.6%) fewer had attained a higher education compared with individuals from the comparison cohort. Siblings of meningococcal meningitis patients also had lower educational achievements, while educational achievements of siblings of pneumococcal and H. influenzae meningitis patients did not differ substantially from those in the general population. At end of follow-up, 3.8% (90.3% vs 94.1%; 95% CI, 1.1%-6.5%), 10.6% (84.0% vs 94.6%; 95% CI, 5.1%-16.1%), and 4.3% (90.6% vs 94.9%; 95% CI, 2.0%-6.6%) fewer meningococcal, pneumococcal, and H. influenzae meningitis patients were economically self-sufficient and 1.5% (3.7% vs 2.3%; 95% CI, -0.2% to 3.2%), 8.7% (10.0% vs 1.3%; 95% CI, 5.0%-12.4%), and 3.7% (6.2% vs 2.5%; 95% CI, 1.6%-5.8%) more received disability pension compared with individuals from the comparison cohort.
In a Danish population, bacterial meningitis in childhood was associated with lower educational achievement and economic self-sufficiency in adult life. This association may apply particularly to pneumococcal and H. influenzae meningitis, whereas for meningococcal meningitis the lower educational achievement may be family-related.
In this nationwide population-based cohort study using national Danish registries, in the period 1980-2008, our aim was to study employment and receipt of disability pension after central nervous system infections. All patients diagnosed between 20 and 55 years of age with meningococcal (n = 451), pneumococcal (n = 553), or viral (n = 1,433) meningitis or with herpes simplex encephalitis (n = 115), who were alive 1 year after diagnosis, were identified. Comparison cohorts were drawn from the general population, and their members were individually matched on age and sex to patients. Five years after diagnosis, the differences in probability of being employed as a former patient with pneumococcal meningitis or herpes simplex encephalitis versus being a member of the comparison cohorts were -19.9% (95% confidence interval (CI): -24.7, -15.1) and -21.1% (95% CI: -33.0, -9.3), respectively, and the corresponding differences in probability of receiving disability pension were 20.2% (95% CI: 13.7, 26.7) and 16.2% (95% CI: 6.2, 26.3). The differences in probability of being employed or receiving disability pension in former meningococcal or viral meningitis patients versus members of the comparison cohorts were small. In conclusion, pneumococcal meningitis and herpes simplex encephalitis were associated with substantially decreased employment and increased need for disability pension. These associations did not seem to apply to meningococcal meningitis or viral meningitis.