Probabilistic Regression Model Research Articles

Maternal age at birth and daughter's fecundability.

Do daughters of older mothers have lower fecundability? In this cohort study of North American pregnancy planners, there was virtually no association between maternal age ≥35 years and daughters' fecundability. Despite suggestive evidence that daughters of older mothers may have lower fertility, only three retrospective studies have examined the association between maternal age and daughter's fecundability. Prospective cohort study of 6689 pregnancy planners enrolled between March 2016 and January 2020. Pregnancy Study Online (PRESTO) is an ongoing pre-conception cohort study of pregnancy planners (age, 21-45 years) from the USA and Canada. We estimated fecundability ratios (FR) for maternal age at the participant's birth using multivariable proportional probabilities regression models. Daughters of mothers ≥30 years were less likely to have previous pregnancies (or pregnancy attempts) or risk factors for infertility, although they were more likely to report that their mother had experienced problems conceiving. The proportion of participants with prior unplanned pregnancies, a birth before age 21, ≥3 cycles of attempt at study entry or no follow-up was greater among daughters of mothers <25 years. Compared with maternal age 25-29 years, FRs (95% CI) for maternal age <20, 20-24, 30-34, and ≥35 were 0.72 (0.61, 0.84), 0.92 (0.85, 1.00), 1.08 (1.00, 1.17), and 1.00 (0.89, 1.12), respectively. Although the examined covariates did not meaningfully affect the associations, we had limited information on the participants' mother. Differences by maternal age in reproductive history, infertility risk factors and loss to follow-up suggest that selection bias may partly explain our results. Our finding that maternal age 35 years or older was not associated with daughter's fecundability is reassuring, considering the trend towards delayed childbirth. However, having been born to a young mother may be a marker of low fecundability among pregnancy planners. PRESTO was funded by NICHD Grants (R21-HD072326 and R01-HD086742) and has received in-kind donations from Swiss Precision Diagnostics, FertilityFriend.com, Kindara.com, and Sandstone Diagnostics. Dr Wise is a fibroid consultant for AbbVie, Inc. n/a.

Breastfeeding Education and Support to Improve Early Initiation and Exclusive Breastfeeding Practices and Infant Growth: A Cluster Randomized Controlled Trial from a Rural Ethiopian Setting.

Although peer-led education and support may improve breastfeeding practices, there is a paucity of evidence on the effectiveness of such interventions in the Ethiopian context. We designed a cluster-randomized trial to evaluate the efficacy of a breastfeeding education and support intervention (BFESI) on infant growth, early initiation (EI), and exclusive breastfeeding (EBF) practices. We randomly assigned 36 clusters into either an intervention group (n = 249) receiving BFESI by trained Women’s Development Army (WDA) leaders or a control group (n = 219) receiving routine care. The intervention was provided from the third trimester of pregnancy until five months postpartum. Primary study outcomes were EI, EBF, and infant growth; secondary outcomes included maternal breastfeeding knowledge and attitude, and child morbidity. The intervention effect was analysed using linear regression models for the continuous outcomes, and linear probability or logistic regression models for the categorical outcomes. Compared to the control, BFESI significantly increased EI by 25.9% (95% CI: 14.5, 37.3%; p = 0.001) and EBF by 14.6% (95% CI: 3.77, 25.5%; p = 0.010). Similarly, the intervention gave higher breastfeeding attitude scores (Effect size (ES): 0.85SD; 95% CI: 0.70, 0.99SD; p < 0.001), but not higher knowledge scores (ES: 0.15SD; 95% CI: −0.10, 0.41SD; p = 0.173). From the several growth and morbidity outcomes evaluated, the only outcomes with significant intervention effect were a higher mid-upper arm circumference (ES: 0.25cm; 95% CI: 0.01, 0.49cm; p = 0.041) and a lower prevalence of respiratory infection (ES: −6.90%; 95% CI: −13.3, −0.61%; p = 0.033). Training WDA leaders to provide BFESI substantially improves EI and EBF practices and attitude towards breastfeeding.

Self-reported periodontitis and fecundability in a population of pregnancy planners.

Is a history of periodontitis among women associated with reduced fecundability? A history of periodontitis, as assessed by three different self-reported measures, may be associated with reduced fecundability. Periodontitis is a chronic inflammatory condition affecting the hard and soft tissues surrounding the teeth. Few studies have evaluated the association between periodontitis and time to pregnancy, and findings are mixed. It is hypothesized that periodontitis may adversely affect time to pregnancy. We conducted a prospective cohort study of 2764 female pregnancy planners residing in North America (March 2015-June 2020). Eligible participants had been attempting pregnancy for six or fewer menstrual cycles at enrollment and were not using fertility treatment. Women answered questions about their oral health. Pregnancy was ascertained via bi-monthly follow-up questionnaires. We used proportional probabilities regression models to estimate fecundability ratios (FRs) and 95% confidence intervals (CIs) for three different measures indicative of a history of periodontitis: ever diagnosed with periodontitis (N = 265), ever received treatment for periodontitis (N = 299), and ever had an adult tooth become loose on its own (N = 83). We adjusted for potential confounders and precision variables. Women at risk of misclassification of periodontitis diagnosis due to pregnancy-related gingivitis were reclassified in a sensitivity analysis. All three indices of periodontitis may be associated with reduced fecundability. FRs were 0.89 (95% CI 0.75-1.06) comparing women with and without a previous periodontitis diagnosis, 0.79 (95% CI 0.67-0.94) comparing women with and without previous periodontitis treatment, and 0.71 (95% CI 0.44-1.16) comparing women with and without a tooth that became loose. After reclassification of pregnancy-related gingivitis in the sensitivity analysis, the FR for periodontitis diagnosis was 0.83 (95% CI 0.68-1.00). Weaker FRs were observed among parous women as compared with nulliparous women for periodontitis diagnosis and tooth becoming loose, but not for periodontitis treatment. Though we used validated self-report measures of periodontitis, clinical confirmation is the gold standard. These questions may be functioning as markers of different levels of periodontitis severity, but we were unable to measure disease severity in this population. Finally, we cannot eliminate the possibility of unmeasured confounding. This is the first preconception prospective cohort study to evaluate the association between self-reported periodontitis and fecundability. Our results indicate that periodontitis may be associated with lower fecundability. This work was partially funded by R01HD086742/Eunice Kennedy Shriver National Institute of Child Health and Human Development and R21HD072326/Eunice Kennedy Shriver National Institute of Child Health and Human Development. PRESTO has received in-kind donations from Swiss Precision Diagnostics, Sandstone Diagnostics, FertilityFriend.com, and Kindara.com for primary data collection. L.A.W. is a fibroid consultant for AbbVie, Inc. J.C.B., S.W., J.Y., K.J.R., E.E.H., and B.H. have no conflicts of interest to disclose. N/A.

Gendered economic, social and health effects of the COVID-19 pandemic and mitigation policies in Kenya: evidence from a prospective cohort survey in Nairobi informal settlements

ObjectivesCOVID-19 may spread rapidly in densely populated urban informal settlements. Kenya swiftly implemented mitigation policies; we assess the economic, social and health-related harm disproportionately impacting women.DesignA prospective longitudinal cohort study...

Male cellular telephone exposure, fecundability, and semen quality: results from two preconception cohort studies.

To what extent is exposure to cellular telephones associated with male fertility? Overall, we found little association between carrying a cell phone in the front pants pocket and male fertility, although among leaner men (BMI <25 kg/m2), carrying a cell phone in the front pants pocket was associated with lower fecundability. Some studies have indicated that cell phone use is associated with poor semen quality, but the results are conflicting. Two prospective preconception cohort studies were conducted with men in Denmark (n = 751) and in North America (n = 2349), enrolled and followed via the internet from 2012 to 2020. On the baseline questionnaire, males reported their hours/day of carrying a cell phone in different body locations. We ascertained time to pregnancy via bi-monthly follow-up questionnaires completed by the female partner for up to 12 months or until reported conception. We used proportional probabilities regression models to estimate fecundability ratios (FRs) and 95% confidence intervals (CIs) for the association between male cell phone habits and fecundability, focusing on front pants pocket exposure, within each cohort separately and pooling across the cohorts using a fixed-effect meta-analysis. In a subset of participants, we examined selected semen parameters (semen volume, sperm concentration and sperm motility) using a home-based semen testing kit. There was little overall association between carrying a cell phone in a front pants pocket and fecundability: the FR for any front pants pocket exposure versus none was 0.94 (95% CI: 0.0.83-1.05). We observed an inverse association between any front pants pocket exposure and fecundability among men whose BMI was <25 kg/m2 (FR = 0.72, 95% CI: 0.59-0.88) but little association among men whose BMI was ≥25 kg/m2 (FR = 1.05, 95% CI: 0.90-1.22). There were few consistent associations between cell phone exposure and semen volume, sperm concentration, or sperm motility. Exposure to radiofrequency radiation from cell phones is subject to considerable non-differential misclassification, which would tend to attenuate the estimates for dichotomous comparisons and extreme exposure categories (e.g. exposure 8 vs. 0 h/day). Residual confounding by occupation or other unknown or poorly measured factors may also have affected the results. Overall, there was little association between carrying one's phone in the front pants pocket and fecundability. There was a moderate inverse association between front pants pocket cell phone exposure and fecundability among men with BMI <25 kg/m2, but not among men with BMI ≥25 kg/m2. Although several previous studies have indicated associations between cell phone exposure and lower sperm motility, we found few consistent associations with any semen quality parameters. The study was funded by the National Institutes of Health, grant number R03HD090315. In the last 3 years, PRESTO has received in-kind donations from Sandstone Diagnostics (for semen kits), Swiss Precision Diagnostics (home pregnancy tests), Kindara.com (fertility app), and FertilityFriend.com (fertility app). Dr. L.A.W. is a fibroid consultant for AbbVie, Inc. Dr. H.T.S. reports that the Department of Clinical Epidemiology is involved in studies with funding from various companies as research grants to and administered by Aarhus University. None of these studies are related to the current study. Dr. M.L.E. is an advisor to Sandstone Diagnostics, Ro, Dadi, Hannah, and Underdog. Dr. G.J.S. holds ownership in Sandstone Diagnostics Inc., developers of the Trak Male Fertility Testing System. In addition, Dr. G.J.S. has a patent pending related to Trak Male Fertility Testing System issued. N/A.

Brazilian Companies’ Dividend Payout in a Political Uncertainty Scenario

The analysis of the determinants of the dividend payout policy becomes even more relevant in a context of crisis. In this scenario, companies wonder which strategy shall prevail—either to keep the payout ratio constancy to signal to the market positive aspects about themselves or to adapt it to the external conjuncture, protecting themselves from future uncertainties. This being so, this study aims at identifying the determinants of the dividend payout policy, in the period before and after the former President Dilma Rousseff’s impeachment, by using logarithmic and probabilistic regression models. To this end, a sample of Brazilian non-financial publicly-held companies is considered, whose data are obtained from the Capital IQ base. As a result, the corporate dividend policy is identified as not being affected by the market environment. Such a fact indicates that Brazilian companies choose to maintain their dividend payout policy, even in scenarios of political uncertainty. This study differs from the others for analyzing the relationship between dividend payout decisions, whether in times of stability or in political and economic crisis.

Reverse Party Favoritism in Times of Pandemics: Evidence from Poland

There is an abundant empirical literature demonstrating party favoritism whereby the central government is prone to disburse financial transfers to favor aligned local governments. This contrasts with much scarcer evidence on reverse party favoritism, i.e. aligned local governments offering non-pecuniary support to the central government in times of elections. In this paper I show that such reverse party favoritism exists. To demonstrate it, I exploit the fact that during the SARS-CoV-2 pandemic crisis, the Polish government was keen to launch postal voting in the presidential elections scheduled for May 2020. The organization of these elections hinged on the Polish Post getting access to the lists of voters, which were in the possession of heads of the municipal executive (mayors). Since the relevant legislation on postal voting had not been enacted on time, the vast majority of local executives refused to share their lists of voters. Nonetheless, numerous mayors did transfer the lists to the Post. By employing a set of standard (linear probability and logistic) regression models and regression discontinuity design, I show that the political alignment of mayors with the central government leads to approximately 20–25 percentage points greater likelihood of transferring the lists of voters to the Polish Post. This difference in probabilities tends to be smaller in cases of divided governments but not in cases of higher political contestability.

Factors Influencing Dietary Diversity in Infants in India: Study Undertaken in Two Districts

Adequate feeding practices in early life have a lasting impact on child nutrition and development. This paper examines the dietary diversity and its associated factors among children aged 6-12 months, in the age that they transition from breastfeeding to complementary feeding, in two districts in India: Udupi (Karnataka) and Sambalpur (Odisha). In 2019, a citizen-led survey, that can be scaled up further very rapidly and cost-effectively, was conducted covering 976 mothers of children below 1 year of age by 90 trained local volunteers. The survey tool uses the Knowledge, Access and Practices Framework and was developed, tested and refined over 4 years through diverse pilots in various locations in India. In the sample, only 12% children aged 6-12 months met the WHO’s minimum dietary diversity requirement. A linear probability regression model was used to assess significant factors for an adequate diversified diet intake in infants. Maternal education, child’s age and meal frequency were found to be significantly associated with dietary diversity. Other factors such as household wealth, gender of child, birth order and homegrown gardens did not present a strong association. Integrated interventions targeted at mothers and children that include nutrition education components into mothers’ education are more likely to be effective in improving infant dietary diversity.

Gender specific differences in COVID-19 knowledge, behavior and health effects among adolescents and young adults in Uttar Pradesh and Bihar, India.

On March 24, 2020 India implemented a national lockdown to prevent spread of the novel Coronavirus disease (COVID-19) among its 1.3 billion people. As the pandemic may disproportionately impact women and girls, this study examines gender differences in knowledge of COVID-19 symptoms and preventive behaviors, as well as the adverse effects of the lockdown among adolescents and young adults. A mobile phone-based survey was implemented from April 3-22, 2020 in Uttar Pradesh and Bihar among respondents randomly selected from an existing cohort study. Respondents answered questions related to demographics, COVID-19 knowledge, attitudes, and preventive behaviors practiced, and impacts on social, economic and health outcomes. Descriptive analyses and linear probability regression models were performed for all participants and separately for men and women. A total of 1,666 adolescents and young adults (18-24 years old) were surveyed; 70% were women. While most participants had high awareness of disease symptoms and preventive behaviors, there was variation by gender. Compared to men, women were seven percentage points (pp) less likely to know the main symptoms of COVID-19 (coeff = -0.071; 95% confidence interval: -0.122 - -0.021). Among women, there was variation in knowledge by education level, urban residence, and household wealth. Women were 22 pp less likely to practice key preventive behaviors compared to men (coeff = -0.222; 95% CIL -0.263, -0.181). Women were also more likely to report recent depressive symptoms than men (coeff = 0.057; 95% CI: 0.004, 0.109). Our findings underscore that COVID-19 is already disproportionately impacting adolescent girls and young women and that they may require additional targeted, gender-sensitive messaging to foster behavior change. Gender-sensitive information campaigns and provision of health services must be accessible and provide women and girls with needed resources and support during the pandemic to ensure gains in public health and gender equity are not lost.

Residential proximity to major roads and fecundability in a preconception cohort.

Among 7,342 female pregnancy planners from the United States and 1,448 from Canada, we examined the association between residential proximity to major roads and fecundability, the per-cycle probability of conception. From 2013 to 2019, women 21-45 years old who were trying to conceive without fertility treatment completed an online baseline questionnaire and follow-up questionnaires every 8 weeks for up to 12 months or until pregnancy. We geocoded residential addresses reported at baseline and during follow-up, and calculated distance to nearest major roads and length of major roads within buffers of 50, 100, 300, and 400 meters around the residence as proxies for traffic-related air pollution. We used proportional probabilities regression models to estimate fecundability ratios (FRs) and 95% confidence intervals (CIs), adjusting for individual- and neighborhood-level characteristics. In the United States, the FR comparing women who lived <50 meters with those who lived ≥400 meters from the closest major road was 0.88 (95% CI = 0.80, 0.98). The association among Canadian women was similar in magnitude, but less precise (FR = 0.93; 95% CI = 0.74, 1.16). Likewise, length of major roads within buffers of 50 and 100 meters was associated with lower fecundability in both countries; associations were attenuated within larger buffers. These results are consistent with the hypothesis that traffic-related air pollution or other near-road exposures may adversely affect fecundability.

Explaining racial-ethnic differences in hypertension and diabetes control among veterans before and after patient-centered medical home implementation.

Patient-centered medical homes (PCMH) are primary care delivery models that improve care access and population-level health outcomes, yet they have not been observed to narrow racial-ethnic disparities in the Veteran Health Administration (VHA) or other health systems. We aimed to identify and compare underlying drivers of persistent hypertension and diabetes control differences between non-Hispanic Black (Black) and Hispanic versus non-Hispanic White (White) patients before and after PCMH implementation in the VHA. Among Black and Hispanic versus White VHA primary care patients in 2009 (nhypertension = 26,906; ndiabetes = 21,141) and 2014 (nhypertension = 83,809; ndiabetes = 38,887), we retrospectively examined hypertension control (blood pressure<140/90) and diabetes control (hemoglobin A1c <9) obtained through random chart abstraction of patient health records nationally via VHA’s quality monitoring program. We fit linear probability regression models, adjusting for age, gender, comorbidity, and socioeconomic status (SES). Blinder-Oaxaca and Smith-Welch decomposition methods were used to parse out explained and unexplained contributors to health disparity between racial-ethnic groups pre- and post-PCMH implementation. Compared to White patients, hypertension and diabetes control remained significantly lower for Black (-6.2%[0.4%] and -3.1%[0.6%], respectively; p’s<0.001) and Hispanic (-1.4%[0.8%] and -4.0%[1.0%], respectively; p’s<0.001) patients following VHA PCMH implementation. Most racial-ethnic differences (55.7–92.3%; all p<0.05) were not attributed to age, gender, comorbidity, and SES. The contribution of explained versus unexplained factors did not significantly change over time. While many explanations for persistent racial-ethnic disparities in disease control among veterans exist, our study did not find that it was due to an influx of “sick” or “socioeconomically vulnerable” patients into the VHA following PCMH implementation. Instead, unexplained differences may be due to differential healthcare and community experiences (e.g., discrimination). Understanding underlying pathways leading to health disparities will better inform policy and clinical interventions to improve PCMH care delivery to racial-ethnic minority patients in health systems.

Gender Specific Differences in COVID-19 Knowledge, Behavior and Health Effects Among Adolescents and Young Adults in Uttar Pradesh and Bihar, India

Background: On March 24, 2020 India implemented a national lockdown to prevent spread of the novel Coronavirus disease (COVID-19) among its 1.3 billion people. The pandemic may disproportionately impact women and girls. This study examines gender differences in knowledge of COVID-19 symptoms and preventive behaviors, as well as the adverse secondary health effects of the lockdown.Methods: A mobile phone-based survey was implemented from April 3-22, 2020 in Uttar Pradesh and Bihar among respondents randomly selected from an existing cohort study. Respondents answered questions related to demographics, COVID-19 knowledge, attitudes, and preventive behaviors practiced, and impacts on social, economic and health outcomes. Descriptive analyses and linear probability regression models were performed for all participants and separately for males and females.Findings: 1,666 adolescent and young adults (18-24 years old) were surveyed; 70% female. While most participants had high awareness of disease symptoms and preventive behaviors, there was variation by gender. Compared to males, females were seven percentage points (pp) less likely to know the main symptoms of COVID-19 (coeff = -0·071; 95% confidence interval: -0·122 - -0·021). Among females, there was variation by education level, urban residence, and household wealth. Females were 22 pp less likely to practice key preventive behaviors (coeff = -0·222; 95% CIL -0·263, -0·181); among female respondents, knowledge was the only factor significantly associated with doing the behaviors. Females were more likely to report recent depressive feelings than males (coeff =0·057; 95% CI: 0·004, 0·109).Interpretation: Wide gender gaps in knowledge, adoption of preventive behaviors, and adverse mental health effects were identified, indicating that COVID-19 is already disproportionately impacting adolescent and young women. Gender-sensitive information campaigns and provision of health services must be accessible and provide support during the pandemic to ensure gains in public health and gender equity are not lost.Funding: None.Declaration of Interests: The authors have no personal or financial relationships to disclose.Ethics Approval Statement: We received expedited ethical approval from the Population Council’s Institutional Review Board (IRB) by meeting criteria for research conducted during COVID-19. The IRB permitted data collection with existing cohorts for participants with previous consent provided the research aligned with national mitigation efforts. The UDAYA study protocol originally received IRB approval in 2015 for longitudinal data collection. Participants were told they could terminate the study at any time or skip any sections. No incentives were offered for taking part in the study.

FrDriver: A Functional Region Driver Identification for Protein Sequence.

Identifying cancer drivers is a crucial challenge to explain the underlying mechanisms of cancer development. There are many methods to identify cancer drivers based on the single mutation site or the entire gene. But they ignore a large number of functional elements with medium in size. It is hypothesized that mutations occurring in different regions of the protein sequence have different effects on the progression of cancer. Here, we develop a novel functional region driver(frDriver) identification method based on Bayesian probability and multiple linear regression models to identify protein regions that can regulate gene expression levels and have high functional impact potential. Combining gene expression data and somatic mutation data, with functional impact scores(SIFT, PROVEAN) as a priori knowledge, we identified cancer driver regions that are most accurate in predicting gene expression levels. We evaluated the performance of frDriver on the BRCA and GBM datasets from TCGA. The results showed that frDriver identified known cancer drivers and outperformed the other three state-of-the-art methods(eDriver, ActiveDriver and OncodriveCLUST). In addition, we performed KEGG pathway and GO term enrichment analysis, and the results indicated that the cancer drivers predicted by frDriver were related to processes such as cancer formation and gene regulation.

Persistent sex disparity in liver transplantation rates

BackgroundStudies have demonstrated that there are sex disparities in the rate of liver transplantation. However, little is known statistically about whether this disparity is caused by liver compartment size, Model for End-Stage Liver Disease adjustments, or regional differences. MethodsWe use retrospective data from the United Network for Organ Sharing Standard Treatment Analysis and Research data files for liver transplantation from 1995 through 2012. The final sample consists of 150,149 patients. These data contain information on all individuals who registered for the liver transplant waiting list as well as updated outcome data. Linear probability and logistic regression models were both used. ResultsWomen were 4.8 percentage points less likely to receive a transplant. Adjustment for race, weight, body mass index, region, education, and other characteristics attenuated the sex difference by roughly 19% (from 4.8 to 3.9 percentage points). The disparity was consistent across the 11 United Network for Organ Sharing allocation regions. Comparing the heaviest women to the lightest men, the disparity flipped. Pairwise comparisons between men and women of various sizes suggest that disparities in favor of men increase with the ratio of male-to-female size. ConclusionOur results document persistent sex disparity in liver transplantation, only 19% of which is explained by size differentials between men and women. Differences in rates of transplantation are increasing in the ratio of male-to-female height and weight, suggesting that some of the disparity is explained by differences in liver compartment size.

Post-partum interval and time to pregnancy in a prospective preconception cohort.

Little is known about the influence of the post-partum interval-defined as the time between giving birth and attempting to conceive again-on subsequent fecundability. We evaluated the association between the post-partum interval and fecundability in Pregnancy Study Online (PRESTO), a web-based prospective preconception cohort of pregnancy planners from the United States and Canada. Eligible women were aged 21-45years, attempting pregnancy, and not using fertility treatment. Women completed a baseline questionnaire to ascertain information on demographics, life style factors, and reproductive history, including detailed information on all previous pregnancies. They completed bi-monthly follow-up questionnaires for up to 12months to update pregnancy status over time. We used proportional probabilities regression models to estimate fecundability ratios (FRs) and 95% confidence intervals (CIs) adjusted for sociodemographic and reproductive history covariates. Analyses were restricted to multiparous women who had been attempting pregnancy with the same male partner for ≤6 menstrual cycles at enrolment. During 2013-2019, 1489 female participants contributed 959 pregnancies and 5003 cycles. The median post-partum interval was 18months. Compared with a 12- to 23-month post-partum interval, FRs for post-partum intervals of <12, 24-47, and ≥48months were 0.89 (95% CI 0.77, 1.04), 1.06 (95% CI 0.91, 1.23), and 0.81 (95% CI 0.62, 1.05), respectively. When restricting to women without a history of subfertility, results were consistent for long post-partum interval and attenuated for short post-partum interval. Among North American pregnancy planners, long post-partum intervals (≥48months) were associated with slightly reduced fecundability. Short post-partum intervals (<12months) were weakly associated with reduced fecundability in some subgroups including women with a history of caesarean delivery and planned pregnancies.

Glycemic load, dietary fiber, and added sugar and fecundability in 2 preconception cohorts

Glycemic load (GL) reflects the quantity and quality of carbohydrates in the diet; dietary fiber and added sugar are components of GL. Few epidemiologic studies have assessed the association between these dietary factors and fecundability. We prospectively evaluated the associations of GL, total carbohydrates, dietary fiber, and added sugar with fecundability. Snart Foraeldre (SF) and Pregnancy Study Online (PRESTO) are parallel web-based prospective preconception cohorts of couples attempting to conceive in Denmark and North America. At baseline, female participants completed a web-based questionnaire on demographic and lifestyle factors and a validated FFQ. We calculated GL, total carbohydrate intake, total dietary fiber, carbohydrate-to-fiber ratio, and added sugar based on reported frequencies for individual foods, standard recipes for mixed foods, and average serving sizes. The analysis included 2709 SF participants and 4268 PRESTO participants. We used proportional probabilities regression models to estimate fecundability ratios (FR) and 95% CIs. Compared with an average daily GL of ≤100, FRs for an average daily GL of ≥141 were 0.89 (95% CI: 0.73, 1.08) in SF and 0.87 (95% CI: 0.77, 0.98) in PRESTO participants. Compared with consuming ≤16 g/d of dietary fiber, FRs for consuming ≥25 g/d were 0.99 (95% CI: 0.81, 1.22) in SF and 1.06 (95% CI: 0.94, 1.20) in PRESTO. Compared with a carbohydrate-to-fiber ratio of ≤8, FRs for a ratio of ≥13 were 0.86 (95% CI: 0.73, 1.01) in SF and 0.87 (95% CI: 0.78, 0.98) in PRESTO. Compared with ≤27 g/d of added sugar, FRs for ≥72 g/d were 0.87 (95% CI: 0.68, 1.10) in SF and 0.86 (95% CI: 0.75, 0.99) in PRESTO participants. Among women attempting to conceive in Denmark and North America, diets high in GL, carbohydrate-to-fiber ratio, and added sugar were associated with modestly reduced fecundability.

Association of Asthma Diagnosis and Medication Use with Fecundability: A Prospective Cohort Study.

PurposeAsthma has been positively associated with irregular menses and infertility in some studies, but data are limited on the relation between asthma medication use and fecundability (i.e., average per-cycle probability of conception among non-contracepting couples). This study examines the extent to which a history of asthma, asthma medication use, and age at first asthma diagnosis are associated with fecundability among female pregnancy planners.Participants and MethodsPregnancy Study Online (PRESTO) is an ongoing, web-based preconception cohort study of couples aged 21–45 years from North America. Between July 2013 and July 2019, a total of 10,436 participants enrolled in PRESTO, and 8286 were included in the present analysis. At study enrollment, women reported whether they had ever been diagnosed with asthma and, if so, the year they were first diagnosed. Women who reported ever being diagnosed with asthma were asked about medication use, including medication type and frequency of use. Participants completed follow-up questionnaires every 8 weeks for up to 12 months or until pregnancy. Proportional probabilities regression models were used to estimate fecundability ratios (FRs) and 95% confidence intervals (CIs), adjusting for potential confounders. Fecundability ratios below 1.00 indicate reduced probability of conception.ResultsThere was little association between a history of asthma diagnosis or asthma medication use and fecundability. Compared with no history of asthma, the FR for ever-diagnosis of asthma with medication use was 1.02 (95% CI: 0.91–1.15) and for ever-diagnosis of asthma without medication use was 1.00 (95% CI: 0.91–1.09). Highest intensity asthma medication use (daily plus extra dosing for symptoms), combination inhaled corticosteroid and long-acting beta-agonist inhaler use, and a first diagnosis of asthma after age 17 years were associated with small reductions in fecundability.ConclusionThe present study provides little evidence that asthma or asthma medication use is adversely associated with fecundability.

A prospective study of influenza vaccination and time to pregnancy

BackgroundAlthough pregnancy planners are a priority group for influenza vaccination in the United States, little is known about the extent to which influenza vaccination affects fecundability. MethodsWe analyzed data from Pregnancy Study Online (PRESTO), an ongoing preconception cohort study of North American pregnancy planners. During June 2013 to August 2019, 8654 female participants and 2137 of their male partners completed a baseline questionnaire and were followed until reported pregnancy, fertility treatment initiation, loss to follow-up, or 12 menstrual cycles of attempt time, whichever came first. At baseline, male and female participants reported whether they received an influenza vaccination in the past year and the date of vaccination. We used proportional probabilities regression models to estimate fecundability ratios (FR) and 95% confidence intervals (CI) comparing those who did and did not report influenza vaccination, adjusting for demographics, anthropometrics, behavioral factors, and medical history. ResultsInfluenza vaccination in the past year was more common among female participants than male participants (47% vs. 37%). FRs were 1.04 (95% CI: 0.98–1.10) for female vaccination and 1.03 (95% CI: 0.93–1.14) for male vaccination. Among the 2137 couples with complete data on both partners, for 40% neither partner was vaccinated, 23% had female-only vaccination, 9% had male-only vaccination, and in 28% both partners were vaccinated. Compared with couples in which neither participant was vaccinated, FRs were 1.13 for female-only vaccination (95% CI: 0.99–1.29), 0.94 for male-only vaccination (95% CI: 0.78–1.12), and 1.07 when both partners were vaccinated (95% CI: 0.94–1.21). When restricted to recent vaccination before peak influenza season, results were similar. ConclusionsOur data indicate no adverse effect of influenza vaccination on fecundability.

Dietary phytoestrogen intakes of adult women are not strongly related to fecundability in 2 preconception cohort studies

Phytoestrogens are plant-derived hormonally active compounds found in soy, cruciferous vegetables, nuts, and seeds. Although phytoestrogens have been associated with altered endogenous hormonal activity, luteal phase deficiency, and reduced endometrial decidualization, the literature reporting examinations of phytoestrogen intake and fertility presents mixed findings. We sought to evaluate prospectively the association between dietary phytoestrogen intake (isoflavones, lignans, and coumestans) and fecundability, the per-cycle probability of conception, in 2 cohorts of women planning pregnancy. Pregnancy Study Online (PRESTO) and Snart Foraeldre (SF) are parallel web-based preconception cohort studies of women from North America and Denmark, respectively, who are trying to conceive. Participants complete an online baseline questionnaire on sociodemographic, lifestyle, and medical factors. We ascertained intake of individual phytoestrogens from validated FFQs. We measured fecundability using data on menstruation and pregnancy status from bimonthly follow-up questionnaires. We analyzed data from 4880 PRESTO and 2898 SF female study participants who had been attempting conception for ≤6 cycles at study entry. We used proportional probabilities regression models to estimate fecundability ratios (FRs) and 95% CIs. Phytoestrogen intake varied across cohorts, yet was associated with higher socioeconomic status and healthier behaviors in both cohorts. After adjustment for potential confounders, phytoestrogen intake was not substantially associated with fecundability in either cohort. We observed some evidence of improved fecundability with increasing isoflavone intake among women age ≥30 years in PRESTO (FR: 1.12; 95% CI: 0.94, 1.34, for comparison of ≥90th with <25th percentile intake) and SF (corresponding FR: 1.19; 95% CI: 0.92, 1.55). Lignan intake was associated with slightly increased fecundability in SF (FR for comparison of 75th to 90th with <25th percentile: 1.10; 95% CI: 0.96, 1.26), but decreased fecundability in PRESTO (FR for comparison of ≥90th with <25th percentile: 0.83; 95% CI: 0.72, 0.97). We did not observe strong associations between phytoestrogen intake and prospectively-measured fecundability among North American or Danish pregnancy planners.

Pesticide residue intake from fruits and vegetables and fecundability in a North American preconception cohort study

Intake of conventionally-grown fruits and vegetables with higher levels of pesticide residue contamination has been associated with poorer semen quality and lower probability of live birth among couples undergoing fertility treatment. We examined the association between dietary intake of pesticide residues and fecundability, the per cycle probability of conception, in a preconception cohort of pregnancy planners. We enrolled women aged 21–45 years who were attempting to conceive without use of fertility treatment into Pregnancy Study Online (PRESTO) from June 2013 through September 2019. Participants completed a baseline questionnaire on demographics, lifestyle factors, and medical and reproductive histories, and bimonthly follow-up questionnaires for up to 12 months or until reported conception. Ten days after baseline, participants completed the National Cancer Institute’s Diet History Questionnaire II, a validated food frequency questionnaire. Using data from the USDA Pesticide Data Program, we classified fruits and vegetables as having high or low pesticide residues using a validated method. We examined the relation between greater intake of high- and low-pesticide residue fruits and vegetables with fecundability using proportional probabilities regression models, adjusted for potential confounders and accounting for consumption of organic produce. We restricted our analysis to 5234 women who had been attempting conception for ≤6 cycles at study entry, and further stratified by pregnancy attempt time at study entry (<3 vs. 3–6 cycles) to evaluate potential for reverse causation. Intakes of high- and low-pesticide residue fruits and vegetables were not appreciably related to fecundability in the full sample, or among women trying to conceive for <3 cycles at study entry. However, among women trying to conceive for 3–6 cycles at study entry, both high- and low-pesticide residue fruit and vegetable intakes were strongly inversely related to fecundability, indicating potential reverse causation bias. These results do not support the hypothesis that intake of pesticide residues from conventionally-grown fruits and vegetables is harmful to fertility, although non-differential exposure misclassification may have attenuated our findings.