Body mass index, physical activity and fecundability in a North American preconception cohort study

Why does Polycystic Ovary Syndrome (PCOS) Need Long-term Management?

BACKGROUND

Polycystic ovary syndrome (PCOS) is a frequent female reproductive endocrine disease. It has been associated with a number of severe reproductive and metabolic abnormalities. However, there are still open questions especially regarding the best long-term management.

METHODS

We summarized the literature focused on the symptoms and negative long-term consequences of untreated PCOS and the existing options for the treatment. We reviewed the Pubmed and China National Knowledge Infrastructure databases and the relevant literature for the last 20 years. Included in this review also are new results of own (published) research and own experience from treating daily more than 100 PCOS patients.

RESULTS

Obesity is one of the most common findings. It can cause abnormal ovulations which can lead to infertility. Important long-term consequences can be adverse pregnancy outcomes. There is an agreement that the risk of endometrial cancer can be increased. Insulin resistance, important within the pathophysiology of PCOS, predisposes patients to metabolic dysfunction and increased risk of type 2 diabetes mellitus. Lifestyle modifications including dietary changes, exercise and weight loss are first-line interventions for many patients. Well known drug treatments such as metformin, oral contraceptives, etc. should be selected according to the individual situation and patients' needs. Regarding newer methods in the long-term management of PCOS, we found that orlistat may help to achieve weight loss and to improve lipid and glucose metabolism.

CONCLUSION

In addition to pharmacological interventions, long-term standardized individualized management of PCOS patients is needed to achieve fertility and to reduce the risk of metabolic related diseases.

The Risks Associated With Obesity in Pregnancy

BACKGROUND

Approximately one-third of all women of childbearing age are overweight or obese. For these women, pregnancy is associated with increased risks for both mother and child.

METHODS

This review is based on pertinent publications retrieved by a selective search of PubMed, with special attention to current population-based cohort studies, systematic reviews, meta-analyses, and controlled trials.

RESULTS

Obesity in pregnancy is associated with unfavorable clinical outcomes for both mother and child. Many of the risks have been found to depend linearly on the body-mass index (BMI). The probability of conception declines linearly, starting from a BMI of 29 kg/m2, by 4% for each additional 1 kg/m2 of BMI (hazard ratio 0.96, 95% confidence interval: [0.91; 0.99]). A 10% increase of pregravid BMI increases the relative risk of gestational diabetes and that of preeclampsia by approximately 10% each. A 5 kg/m2 increase of BMI elevates the relative risk of intrauterine death to 1.24 [1.18; 1.30]. An estimated 11% of all neonatal deaths can be attributed to the consequences of maternal overweight and obesity. Nonetheless, in most randomized controlled trials, nutritional and lifestyle interventions did not bring about any clinically relevant reduction in the incidence of gestational diabetes and fetal macrosomia.

CONCLUSION

The risks associated with obesity in pregnancy cannot necessarily be influenced by intervention. Preventive measures aimed at normalizing body weight before a woman becomes pregnant are, therefore, all the more important.

Determining the association between physical activity prior to conception and pregnancy rate: A systematic review and meta-analysis of prospective cohort studies

We investigated the association between physical activity (PA) before pregnancy and pregnancy rate according to intensity and amount of exercise. Eleven prospective cohort studies were included in this meta-analysis. Any amount of moderate-intensity PA was associated with a statistically higher rate of pregnancy compared to that in patients with no PA (p < .05). Any amount of vigorous PA was associated with decreased pregnancy rate; regular PA was associated with decreased infertility (p > .05). In contrast, vigorous PA was associated with increased infertility (p > .05). Therefore, women who are preparing for pregnancy are recommended to perform regular, moderate-intensity PA.

Female adiposity and time-to-pregnancy: a multiethnic prospective cohort

STUDY QUESTION

Are higher overall and central adiposity associated with reduced fecundability, measured by time-to-pregnancy (TTP), in Asian women?

SUMMARY ANSWER

Higher overall adiposity, but not central adiposity, was associated with longer TTP in Asian women.

WHAT IS KNOWN ALREADY

High body mass index (BMI) has been associated with a longer TTP, although the associations of body composition and distribution with TTP are less clear. There are no previous studies of TTP in Asian women, who have a relatively higher percentage of body fat and abdominal fat at relatively lower BMI.

STUDY DESIGN, SIZE, DURATION

Prospective preconception cohort using data from 477 Asian (Chinese, Malay and Indian) women who were planning to conceive and enrolled in the Singapore PREconception Study of long-Term maternal and child Outcomes (S-PRESTO) study, 2015-2017.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Women's mean age was 30.7 years. Overall adiposity was assessed by BMI, sum of 4-site skinfold thicknesses (SFT) and total body fat percentage (TBF%, measured using air displacement plethysmography); central adiposity was assessed by waist circumference (WC), waist-to-hip ratio (WHR), waist-to-height ratio (WHtR) and A body Shape Index (ABSI). Pregnancy occurring within one year from recruitment was ascertained by ultrasonography. Those who did not conceive within one year of recruitment, were lost to follow-up, or initiated fertility treatment were censored. TTP was measured in cycles. Discrete-time proportional hazards models were used to estimate the fecundability ratio (FR) and 95% confidence interval (CI) for each anthropometric measure in association with fecundability, adjusting for confounders.

MAIN RESULTS AND THE ROLE OF CHANCE

Compared to women with a normal BMI of 18.5-22.9 kg/m2, women with higher BMI of 23-27.4 and ≥27.5 kg/m2 showed lower FR of 0.66 (95% CI 0.45, 0.97) and 0.53 (0.31, 0.89), respectively. Compared to women in the lowest quartile of SFT (25-52.9 mm), those in the highest quartile of ≥90.1 mm showed lower FR of 0.58 (95% CI 0.36, 0.95). Compared to women in the lowest quartile of TBF% (13.6-27.2%), those in the upper two quartiles of 33.0-39.7% and ≥39.8% showed lower FR of 0.56 (95% CI 0.32, 0.98) and 0.43 (0.24, 0.80), respectively. Association of high BMI with reduced fecundability was particularly evident among nulliparous women. Measures of central adiposity (WC, WHR, WHtR, ABSI) were not associated with fecundability.

LIMITATIONS REASONS FOR CAUTION

Small sample size could restrict power of analysis.The analysis was confined to planned pregnancies, which could limit generalizability of findings to non-planned pregnancies, estimated at around 44% in Singapore. Information on the date of last menstrual period for each month was not available, hence the accuracy of self-reported menstrual cycle length could not be validated, potentially introducing error into TTP estimation. Measures of exposures and covariates such as cycle length were not performed repeatedly over time; cycle length might have changed during the period before getting pregnant.

WIDER IMPLICATIONS OF THE FINDINGS

Other than using BMI as the surrogate measure of body fat, we provide additional evidence showing that higher amounts of subcutaneous fat that based on the measure of SFT at the sites of biceps, triceps, suprailiac and subscapular, and TBF% are associated with longer TTP. Achieving optimal weight and reducing total percentage body fat may be a potential intervention target to improve female fertility. The null results observed between central adiposity and TTP requires confirmation in further studies.

STUDY FUNDING/COMPETING INTEREST(S)

This research is supported by Singapore National Research Foundation under its Translational and Clinical Research Flagship Programme and administered by the Singapore Ministry of Health's National Medical Research Council, (NMRC/TCR/004-NUS/2008; NMRC/TCR/012-NUHS/2014). Additional funding is provided by the Singapore Institute for Clinical Sciences, Agency for Science Technology and Research (A*STAR), Singapore. Y.S.C., K.M.G., F.Y. and Y.S.L. have received reimbursement to speak at conferences sponsored by companies selling nutritional products. Y.S.C., K.M.G. and S.Y.C. are part of an academic consortium that has received research funding from Abbott, Nutrition, Nestle and Danone. Other authors declared no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Evolutionary Theories and Men's Preferences for Women's Waist-to-Hip Ratio: Which Hypotheses Remain? A Systematic Review

Over the last 25 years, a large amount of research has been dedicated to identifying men's preferences for women's physical features, and the evolutionary benefits associated with such preferences. Today, this area of research generates substantial controversy and criticism. I argue that part of the crisis is due to inaccuracies in the evolutionary hypotheses used in the field. For this review, I focus on the extensive literature regarding men's adaptive preferences for women's waist-to-hip ratio (WHR), which has become a classic example of the just-so storytelling contributing to the general mistrust toward evolutionary explanations of human behavior. The issues in this literature originate in the vagueness and incompleteness of the theorizing of the evolutionary mechanisms leading to mate preferences. Authors seem to have rushed into testing and debating the effects of WHR on women's attractiveness under various conditions and using different stimuli, without first establishing (a) clear definitions of the central evolution concepts (e.g., female mate value is often reduced to an imprecise concept of "health-and-fertility"), and (b) a complete overview of the distinct evolutionary paths potentially at work (e.g., focusing on fecundability while omitting descendants' quality). Unsound theoretical foundations will lead to imprecise predictions which cannot properly be tested, thus ultimately resulting in the premature rejection of an evolutionary explanation to human mate preferences. This paper provides the first comprehensive review of the existing hypotheses on why men's preferences for a certain WHR in women might be adaptive, as well as an analysis of the theoretical credibility of these hypotheses. By dissecting the evolutionary reasoning behind each hypothesis, I show which hypotheses are plausible and which are unfit to account for men's preferences for female WHR. Moreover, the most cited hypotheses (e.g., WHR as a cue of health or fecundity) are found to not necessarily be the ones with the strongest theoretical support, and some promising hypotheses (e.g., WHR as a cue of parity or current pregnancy) have seemingly been mostly overlooked. Finally, I suggest some directions for future studies on human mate choice, to move this evolutionary psychology literature toward a stronger theoretical foundation.

A prospective study of physical activity and fecundability in women with a history of pregnancy loss

STUDY QUESTION

Is physical activity (PA) associated with fecundability in women with a history of prior pregnancy loss?

SUMMARY ANSWER

Higher fecundability was related to walking among overweight/obese women and to vigorous PA in women overall.

WHAT IS KNOWN ALREADY

PA may influence fecundability through altered endocrine function. Studies evaluating this association have primarily utilized Internet-based recruitment and self-report for pregnancy assessment and have yielded conflicting results.

STUDY DESIGN, SIZE, DURATION

This is a secondary analysis of the Effects of Aspirin in Gestation and Reproduction (EAGeR) trial (2007-2011), a multisite, randomized controlled trial of preconception-initiated low-dose aspirin.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Healthy women (n = 1214), aged 18-40 and with 1-2 prior pregnancy losses, were recruited from four US medical centers. Participants were followed for up to six menstrual cycles while attempting pregnancy and through pregnancy for those who became pregnant. Time to hCG detected pregnancy was assessed using discrete-time Cox proportional hazard models to estimate fecundability odds ratios (FOR) adjusted for covariates, accounting for left truncation and right censoring.

MAIN RESULTS AND THE ROLE OF CHANCE

The association of walking with fecundability varied significantly by BMI (P-interaction = 0.01). Among overweight/obese women, walking ≥10 min at a time was related to improved fecundability (FOR = 1.82, 95% CI: 1.19, 2.77). In adjusted models, women reporting >4 h/wk of vigorous activity had significantly higher fecundability (FOR = 1.69, 95% CI: 1.24, 2.31) compared to no vigorous activity. Associations of vigorous activity with fecundability were not significantly different by BMI (P-interaction = 0.9). Moderate activity, sitting, and International Physical Activity Questionnaire (IPAQ) categories were not associated with fecundability overall or in BMI-stratified analyses.

LIMITATIONS, REASONS FOR CAUTION

Some misclassification of PA levels as determined by the short form of the IPAQ is likely to have occurred, and may have led to non-differential misclassification of exposure in our study. Information on diet and change in BMI was not collected and may have contributed to some residual confounding in our results. The generalizability of our results may be limited as our population consisted of women with a history of one or two pregnancy losses.

WIDER IMPLICATIONS OF THE FINDINGS

These findings provide positive evidence for the benefits of PA in women attempting pregnancy, especially for walking among those with higher BMI. Further study is necessary to clarify possible mechanisms through which walking and vigorous activity might affect time-to-pregnancy.

STUDY FUNDING/COMPETING INTEREST(S)

This work was funded by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development. The authors report no conflicts of interest in this work.

TRIAL REGISTRATION NUMBER

#NCT00467363.

Intake of Sugar-sweetened Beverages and Fecundability in a North American Preconception Cohort

BACKGROUND

Dietary factors, including sugar-sweetened beverages, may have adverse effects on fertility. Sugar-sweetened beverages were associated with poor semen quality in cross-sectional studies, and female soda intake has been associated with lower fecundability in some studies.

METHODS

We evaluated the association of female and male sugar-sweetened beverage intake with fecundability among 3,828 women planning pregnancy and 1,045 of their male partners in a North American prospective cohort study. We followed participants until pregnancy or for up to 12 menstrual cycles. Eligible women were aged 21-45 (male partners ≥21), attempting conception for ≤6 cycles, and not using fertility treatments. Participants completed a comprehensive baseline questionnaire, including questions on sugar-sweetened beverage consumption during the previous 4 weeks. We estimated time-to-pregnancy from follow-up questionnaires completed every 2 months by the female partner. We calculated adjusted fecundability ratios (FR) and 95% confidence intervals (CIs) according to intake of sugar- sweetened beverages using proportional probabilities regression.

RESULTS

Both female and male intakes of sugar-sweetened beverages were associated with reduced fecundability (FR = 0.81; 95% CI = 0.70, 0.94 and 0.78; 95% CI = 0.63, 0.95 for ≥7 sugar-sweetened beverages per week compared with none, for females and males, respectively). Fecundability was further reduced among those who drank ≥7 servings per week of sugar-sweetened sodas (FR = 0.75, 95% CI = 0.59, 0.95 for females and 0.67, 95% CI = 0.51, 0.89 for males).

CONCLUSIONS

Sugar-sweetened beverages, particularly sodas and energy drinks, were associated with lower fecundability, but diet soda and fruit juice had little association.

A 10-year prospective study of personality and reproductive success: Testing the mediating role of healthy living

OBJECTIVE

There is some evidence that personality relates to childbearing in adulthood but the importance of personality for reproductive capacity is unknown. This study explored cross-time associations between the major dimensions of trait personality and self-reported fertility and fecundity.

METHODS

A representative sample of young Australian adults [n = 4501; age range ≈ 18-44 (women), 18-54 (men)] provided information on personality, fertility, fertility intentions, fecundity and lifestyle factors (cigarette smoking, alcohol consumption, physical activity) in 2006 and again in 2016. Older Australian adults [n = 4359; age ≥ 45 (women), ≥ 55 (men)] provided information on personality, lifestyle factors and completed fertility.

RESULTS

After controlling for sociodemographic factors, completed fertility was associated with higher agreeableness in both sexes, and lower conscientiousness and openness in women. In younger adults, higher levels of openness were associated with fewer children 10 years later in both sexes, and higher extraversion was associated with more children 10 years later in men. The association between fertility intentions and subsequent fertility was stronger among women scoring higher on conscientiousness, and women scoring higher on neuroticism were more likely to acquire medical or health difficulties in having children - an effect that was mediated by higher levels of cigarette smoking.

CONCLUSIONS

The study provides initial evidence for an association between personality and the acquisition of difficulties in having children.

Recent advances in understanding the relationship between long- and short-term weight change and fertility

The impact of excess body weight on fertility is well recognized among both women attempting to conceive spontaneously and those attempting to conceive with medical assistance. Although many leading societies of reproductive medicine have proposed weight loss as a means to counteract the negative consequences of obesity on fertility, there is limited research on this topic. In this review, we provide a brief overview of the recent advances in the literature focused on how long- and short-term weight change affects fertility among women. Overall, despite initial hope that weight loss may be beneficial for fertility, two large well-conducted randomized controlled trials have consistently shown that short-term weight loss among overweight and obese women undergoing infertility treatment does not improve a woman's probability of live birth. The observational evidence among women attempting to conceive without medical assistance also suggests limited benefits of weight loss on fecundity or pregnancy loss. In contrast, substantial weight gain between consecutive pregnancies, in the year prior to pregnancy attempt, and throughout adulthood appears to be harmful for not only time to pregnancy but also pregnancy maintenance. Future research focused on efforts to prevent weight gain during adulthood is needed to better understand whether these types of interventions may have beneficial effects on fertility.

The impact of maternal lifestyle factors on periconception outcomes: a systematic review of observational studies

The main risk factors for important reproductive health issues such as subfertility and perinatal mortality largely originate in the periconception period. To evaluate associations between modifiable maternal lifestyle factors and periconception outcomes, a systematic search was conducted for relevant studies published from 1990 to February 2017 on Embase, Medline, Web of Science, Cochrane database, PubMed and Google Scholar. The initial search identified 6166 articles, of which 49 studies were eligible for inclusion. Fecundity (the capacity to have a live birth) showed significant inverse associations with smoking, alcohol use and poor diet. Studies regarding time to pregnancy showed a decline in fecundity ratios (the monthly conception rate among exposed relative to unexposed couples) with increasing body mass index (BMI). Furthermore, risk of first-trimester miscarriage was found to be increased in smokers, alcohol and caffeine consumers, and with increasing BMI. Vitamin supplement use showed a decrease in this risk. This review demonstrates that maternal modifiable lifestyle factors affect periconception outcomes. If couples planning a pregnancy are more aware and supported to adopt healthy lifestyles during the periconceptional 'window of opportunity', short-term reproductive health as well as health in later life and even of future generations can be further improved.

Differential effects of high-fat diets before pregnancy and/or during pregnancy on fetal growth development

AIMS

The aim of the study was to investigate the effects of high-fat diets before pregnancy and/or during pregnancy on fetal development.

MAIN METHODS

Female mice were fed with standard diets (SD) or high-fat diets (HFD). After 12 weeks, females were mated. In the SD + SD and HFD + SD groups, pregnant mice were fed with standard diets. In the SD + HFD and HFD + HFD groups, pregnant mice were fed with high-fat diets. All pregnant mice were sacrificed on gestational day (GD) 16.

KEY FINDINGS

Fetal weight and crown-rump length were increased in SD + HFD-fed mice, whereas were decreased in HFD + SD-fed mice. The levels of CRP and TNF-α in maternal serum and amniotic fluid were elevated in all HFD-fed mice. Placenta weight was elevated in SD + HFD-fed but not in HFD + SD-fed mice. Blood sinusoid areas, and the number of Ki67-positive cells, a marker of cell proliferation, were elevated in placental labyrinth layer of SD + HFD-fed mice, but decreased in HFD + SD-fed mice. Finally, placental Fatp1, a fatty acid transporter gene, was up-regulated in SD + HFD-fed mice. By contrary, placental Fatp1, and Snat2, an amino acid transporter, were down-regulated in HFD + SD-fed mice. Moreover, the levels of placental FATP4 and SNAT2 were up-regulated in SD + HFD-fed mice.

SIGNIFICANCE

HFD before pregnancy and HFD during pregnancy differentially disturb fetal growth development. HFD before pregnancy-induced fetal SGA might be partially attributed to inflammatory cytokines and mediators derived from maternal adipose tissue. By contrary, HFD during pregnancy-induced fetal overweight may be partially attributed to the increase of placental nutrient transport capacity.

Do the Low WHRs and BMIs Judged Most Attractive Indicate Higher Fertility?

We examine the widely accepted view that very low waist-hip ratios and low body mass indices (BMIs) in women in well-nourished populations are judged attractive by men because these features reliably indicate superior fertility. In both subsistence and well-nourished populations, relevant studies of fertility do not support this view. Rather studies indicate lower fertility in women with anthropometric values associated with high attractiveness. Moreover, low maternal BMI predisposes to conditions that compromise infant survival. Consistent with these findings from the literature, new data from a large U.S. sample of women past reproductive age show that women with lower BMIs in the late teens had fewer live births, controlling for education, marital history, and race. They also had later menarche and earlier menopause compared with women with higher youth BMIs. In addition, data from the 2013 U.S. natality database show that mothers with lower prepregnancy BMIs have an increased risk of producing both low-birth-weight and preterm infants controlling for other relevant variables-conditions that would have adversely affected fitness over almost all of human evolution. Thus, a review of the relevant literature and three new tests fail to support the view that highly attractive women are more fertile.

Mental health, psychotropic medication use, and menstrual cycle characteristics

Purpose

To examine the influence of depressive symptoms, perceived stress, and psychotropic medication use on prospectively assessed menstrual cycle regularity and length.

Participants and methods

Data were obtained from Pregnancy Study Online, a prospective cohort study of pregnancy planners from North America. At baseline, women reported information on demographics, anthropometrics, lifestyle, and medical history, including their use of psychotropic medications. They also completed the Major Depression Inventory and the Perceived Stress Scale. Every 8 weeks for up to 12 months or until conception, women completed follow-up questionnaires to assess changes in psychotropic medication use, perceived stress, and menstrual cycle characteristics (ie, cycle regularity and length). Women who completed at least one follow-up questionnaire from 2013 to 2018 (n=3,346) were included in the primary analyses. A total of 5,439 women were included in secondary analyses utilizing baseline data only. Primary analyses estimated prevalence ratios (PR) and 95% CIs using log-binomial regression models.

Results

Women with severe depressive symptoms at baseline, regardless of psychotropic medication use, had an 80% greater prevalence of irregular cycles during follow-up than women with no or low depressive symptoms (PR =1.80, 95% CI =1.48–2.19). Perceived stress was also associated with the prevalence of irregular cycles during follow-up (PR =1.33, 95% CI =1.14–1.55). Psychotropic medication use was not appreciably associated with menstrual characteristics after controlling for history of diagnosed depression and/or anxiety. Depressive symptoms, perceived stress, and psychotropic medication use showed little association with menstrual cycle length.

Conclusion

Higher levels of depressive symptoms and perceived stress were associated with irregular menstrual cycles, but not appreciably associated with menstrual cycle length. Use of psychotropic medications was not meaningfully associated with cycle regularity or length.

The Effect of Shift Work on Urogenital Disease: a Systematic Review

PURPOSE OF REVIEW

Non-standard shift work schedules negatively impact the overall health of shift workers, and several studies have shown that shift work, specifically, is detrimental to urogenital health. The aims of this study are to systematically review the literature and determine the effect of shift work on the outcomes of hypogonadism, male infertility, lower urinary tract symptoms, and urogenital cancers.

RECENT FINDINGS

Recent evidence supports associations between non-standard shift work and an increase in the frequency of prostate cancer and the severity of erectile dysfunction, lower urinary tract symptoms, and hypogonadal symptoms, as well as worsening of semen parameters and fertility. These associations are strengthened by the presence of shift work sleep disorder (SWSD) which affects up to 20% of shift workers. No studies have assessed the impact of shift work on the frequency or severity of nephrolithiasis, interstitial cystitis, pelvic pain, prostatitis, or urinary tract infections. Non-standard shift work has been associated with a variety of negative health outcomes and urologic complications, especially with concurrent shift work sleep disorder. Recognition of these elevated risks among shift workers can aid in more effective screening for urologic conditions.

Dietary Fat Intake and Fecundability in 2 Preconception Cohort Studies

The association between dietary fat and fertility is not well studied. We evaluated intakes of total fat, saturated fatty acids, monounsaturated fatty acids, polyunsaturated fatty acids, trans fatty acids (TFA), ω-3 fatty acids, and ω-6 fatty acids in relation to fecundability in Danish and North American preconception cohort studies. Women who were attempting to become pregnant completed a validated food frequency questionnaire at baseline. Pregnancy status was updated bimonthly for 12 months or until pregnancy. Fecundability ratios (FR) and 95% confidence intervals were estimated using multivariable proportional probabilities regression. Intakes of total fat and saturated, monounsaturated, polyunsaturated, and ω-6 fatty acids were not appreciably associated with fecundability. TFA intake was associated with reduced fecundability in North American women (for the fourth quartile vs. the first, FR = 0.86, 95% confidence interval (CI): 0.71, 1.04) but not Danish women (for the fourth quartile vs. the first, FR = 1.04, 95% CI: 0.86, 1.25), though intake among Danish women was low. In North America, ω-3 fatty acid intake was associated with higher fecundability, but there was no dose-response relationship (among persons who did not use fish oil supplements: for the fourth quartile vs. the first, FR = 1.40, 95% CI: 1.13, 1.73); no association was found in Danish women, among whom low intake was rare. In the present study, high TFA intake and low ω-3 fatty acid intake were associated with reduced fecundity.

Couples' body composition and time-to-pregnancy

STUDY QUESTION

Is couples' body compositions associated with reduced fecundity as measured by a longer time-to-pregnancy (TTP)?

SUMMARY ANSWER

Couples whose BMI are within obese class II (≥35 kg/m2) have a longer TTP in comparison to leaner (BMI < 25 kg/m2) couples, observed only when both partner's BMI was jointly modeled.

WHAT IS KNOWN ALREADY

Extremes of BMI have been associated with a longer TTP and with less successful assisted reproductive technology (ART) outcomes. To our knowledge, the association between measured adiposity in both partners of the couple and prospectively measured TTP has not been investigated despite pregnancy being a couple-dependent outcome.

STUDY DESIGN, SIZE, DURATION

Prospective cohort with preconception recruitment of 501 couples trying for pregnancy and recruited from 16 counties in Michigan and Texas between 2005 and 2009. Couples were followed daily for up to a year of trying or until a hCG pregnancy.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In-home standardized anthropometric assessment of couples upon enrollment included measured height and weight using calibrated stadiometers and scales, and measured waist and hip circumferences. Discrete-time Cox regression was used to estimate fecundability odds ratios (FORs) and 95% CIs, controlling for potential confounders including age, number of days of vigorous physical activity, serum cotinine concentration, race, education, free cholesterol levels for each partner in partner-specific models and for both partners in couple-based models as well as average acts of intercourse per menstrual cycle and menstrual cycle regularity.

MAIN RESULTS AND THE ROLE OF CHANCE

Neither male nor female partner's BMI was associated with TTP when modeled individually. However, obese class II (BMIs ≥ 35.0 kg/m2) couples experienced a reduction in fecundability in both unadjusted (FOR = 0.45; 95% CI: 0.23, 0.89) and adjusted analyses (aFOR = 0.41; 95% CI: 0.17, 0.98) resulting in a longer TTP in comparison to couples with normal BMI (<25 kg/m2). Female partners' waist circumference ≥88.6 cm was associated with a significant reduction in fecundability in the unadjusted model (FOR = 0.64; 95% CI: 0.48, 0.86) but not in the adjusted model (aFOR = 0.77; 95% CI: 0.55, 1.08) in comparison to females with a smaller (<80 cm) circumference.

LIMITATIONS, REASONS FOR CAUTION

BMI and waist circumference are proxy measures of body composition and residual confounding cannot be eliminated. Findings may not be generalizable to clinical populations.

WIDER IMPLICATIONS OF THE FINDINGS

This is the first cohort study known to us with preconception enrollment of couples who underwent standardized anthropometric assessment and for whom TTP was prospectively measured. The findings underscore the importance of considering both partners' body composition for fecundity outcomes and preconception guidance.

STUDY FUNDING/COMPETING INTEREST(S)

Supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (Contracts #N01-HD-3-3355, N01-HD-3-3356 and N01-HD-3-3358). The authors have no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Dairy intake and fecundability in 2 preconception cohort studies

BACKGROUND

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.

OBJECTIVE

We prospectively evaluated dairy intake in relation to fecundability among women who were planning for pregnancy.

DESIGN

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.

RESULTS

FRs for total dairy intake (≥18 compared with <7 servings/wk) were 1.37 (95% CI: 1.05, 1.78) among 1126 Snart Foraeldre participants and 1.04 (95% CI: 0.78, 1.38) among 1300 PRESTO participants (pooled FR: 1.11; 95% CI: 0.94, 1.31). The elevated FR for total dairy intake among Snart Foraeldre participants was limited to milk consumption and found only among women aged <30 y. There was no clear association between low- or high-fat dairy intake and fecundability in either cohort. Although there was little evidence of an association between dietary intake of calcium, potassium, magnesium, or vitamin D and fecundability, a greater consumption of phosphorus and lactose was associated with slightly higher fecundability in both cohorts.

CONCLUSIONS

Associations between dairy intake and fecundability were generally small and inconsistent across cohorts. Our findings do not support the hypotheses that a greater consumption of high-fat dairy improves fertility or that a greater consumption of lactose or low-fat dairy harms fertility.

Endocrine disrupting chemicals and ovulation: Is there a relationship?

Although the potential for endocrine disrupting chemicals (EDCs) to disrupt female fecundity is great, few studies have assessed the threat to human reproduction. This study investigates levels of organochlorines in relation to their impact on women's menstrual cycles and ovulatory status. To address concerns of the Akwesasne Mohawk community in upstate New York regarding well-established exposure to EDCs, women's fertility and reproductive health endpoints, we recruited 215 women between the ages of 21 and 38 years to measure menstrual cycle characteristics and levels of local pollutants. Of these, 155 women collected saliva over the course of their menstrual cycle allowing for analysis of estradiol and progesterone levels and the determination of ovulatory status in relationship to their serum pollutant levels. A subset of participants (15) who did not commence cycling within a month of their enrollment were not included in the analysis, hence reducing the sample size to 140 participants. Additionally, a lipid panel, estradiol and progesterone were assessed in serum on Day 3 of the menstrual cycle. Median cycle length for women in the sample was 29 days. After aligning the cycles, 110 women were considered ovulatory and 45 (29%) anovulatory. Concentrations of groups of more persistent PCBs congeners, HCB, and p,p'-DDE did not differ significantly with ovulatory status. However, a sub-group of low-chlorinated PCB congeners, considered to be estrogenic were significantly higher among anovulatory women. These findings suggest that certain EDC's, ubiquitous in our environment, may adversely affect menstrual cycles and thus have the capacity to impair reproductive function, including likelihood of conception.