Validity of self-reported time to pregnancy

Maternal exposure to metals and time-to-pregnancy: The MIREC cohort study

OBJECTIVE

To study the association between maternal exposure to arsenic, cadmium, lead, manganese and mercury, time-to-pregnancy (TTP) and infertility.

DESIGN

Pregnancy-based retrospective TTP cohort study.

SETTING

Hospitals and clinics from ten cities across Canada.

POPULATION

A total of 1784 pregnant women.

METHODS

Concentrations of arsenic, cadmium, lead, manganese and mercury were measured in maternal whole blood during the first trimester of pregnancy as a proxy of preconception exposure. Discrete-time Cox proportional hazards models generated fecundability odds ratios (FOR) for the association between metals and TTP. Logistic regression generated odds ratios (OR) for the association between metals and infertility. Models were adjusted for maternal age, pre-pregnancy body mass index, education, income, recruitment site and plasma lipids.

MAIN OUTCOME MEASURES

TTP was self-reported as the number of months of unprotected intercourse to become pregnant. Infertility was defined as TTP longer than 12 months.

RESULTS

A total of 1784 women were eligible for the analysis. Mean ± SD maternal age and gestational age at interview were 32.2 ± 5.0 years, and 11.6 ± 1.6 weeks, respectively. Exposure to arsenic, cadmium, manganese or mercury was not associated with TTP or infertility. Increments of one standard deviation of lead concentrations resulted in a shorter TTP (adjusted FOR 1.09, 95% CI 1.02-1.16); however, the association was not linear when exposure was modelled in tertiles.

CONCLUSION

Blood concentrations of metals at typical levels of exposure among Canadian pregnant women were not associated with TTP or infertility. Further studies are needed to assess the role of lead, if any, on TTP.

Fertility history and intentions of married women, China

Objective

To estimate the proportion of married women in China who intend to become pregnant given the country's pronatalist population policy and to investigate fecundity, with an emphasis on the influence of socioeconomic factors.

Methods

A nationally representative survey of 12 815 married women aged 20 to 49 years (mean: 36.8 years) was conducted during 2019 and 2020. All completed questionnaires, 10 115 gave blood samples and 11 710 underwent pelvic ultrasound examination. Fertility intention was the desire or intent to become pregnant combined with engagement in unprotected sexual intercourse. We defined infertility as the failure to achieve pregnancy after 12 months or more of unprotected intercourse. We considered an anti-Müllerian hormone level < 1.1 ng/mL and an antral follicular count < 7 as indicating an abnormal ovarian reserve.

Findings

Fertility intentions were reported by 11.9% of women overall but by only 6.1% of current mothers (weighted percentages). Fertility intention was significantly less likely among women in metropolises (odds ratio, OR: 0.38; 95% confidence interval, CI: 0.31-0.45) and those with a higher educational level (OR: 0.74; 95% CI: 0.62-0.88). Overall, 18.0% had experienced infertility at any time and almost 30% had an abnormal ovarian reserve on assessment. An abnormal ovarian reserve and infertility were less likely in women in metropolises (P < 0.05) but more likely in obese women (P < 0.05).

Conclusion

The willingness of Chinese married women to give birth remained low, even with relaxation of the one-child policy.

Optimizing preconception care and interventions for improved population health

There is growing literature indicating that optimal preconception health is associated with improved reproductive, perinatal, and pediatric outcomes. Given that preconception care is recommended for all individuals planning a pregnancy, medical providers and public health practitioners have a unique opportunity to optimize care and improve health outcomes for reproductive-aged individuals. Knowledge of the determinants of preconception health is important for all types of health professionals, including policy makers. Although some evidence-based recommendations have already been implemented, additional research is needed to identify factors associated with favorable health outcomes and to ensure that effective interventions are made in a timely fashion. Given the largely clinical readership of this journal, this piece is primarily focused on clinical care. However, we acknowledge that optimizing preconception health for the entire population at risk of pregnancy requires broadening our strategies to include population-health interventions that consider the larger social systems, structures, and policies that shape individual health outcomes.

Examining attention-deficit/hyperactivity disorder and related behavioral disorders by fertility treatment exposure in a prospective cohort

PURPOSE

To evaluate whether underlying infertility and mode of conception are associated with childhood behavioral disorders.

METHODS

Oversampling on fertility treatment exposure using vital records, the Upstate KIDS Study followed 2057 children (of 1754 mothers) from birth to 11 years. Type of fertility treatment and time to pregnancy (TTP) were self-reported. Mothers completed annual questionnaires reporting symptomology, diagnoses, and medications at 7-11 years of age. The information identified children with probable attention-deficit/hyperactivity disorder, anxiety or depression, and conduct or oppositional defiant disorders. We estimated adjusted relative risks (aRR) for disorders by underlying infertility (TTP > 12 months) or treatment exposure groups compared to children born to parents with TTP ≤ 12 months.

RESULTS

Children conceived with fertility treatment (34%) did not have an increased risk of attention-deficit/hyperactivity disorder (aRR): 1.21; 95% CI: 0.88, 1.65), or conduct or oppositional defiant disorders (aRR: 1.31; 0.91, 1.86), but did have an increased risk of anxiety or depression (aRR: 1.63; 1.18, 2.24), which remained elevated even after adjusting for parental mood disorders (aRR: 1.40; 0.99, 1.96). Underlying infertility without the use of treatment was also associated with a risk of anxiety or depression (aRR: 1.82; 95% CI: 0.96, 3.43).

CONCLUSIONS

Underlying infertility or its treatment was not associated with risk of attention-deficit/hyperactivity disorder. Observations of increased anxiety or depression require replication.

Pregnancy Intention, Changes in Pregnancy Intention, and Pregnancy Incidence Among Female Nurses in North America

Importance

Pregnancy intention assessment is a key element of preconception and contraceptive care. The association between a single screening question and the incidence of pregnancy is unknown.

Objective

To prospectively evaluate the dynamics of pregnancy intention and pregnancy incidence.

Design, Setting, and Participants

This prospective cohort study (the Nurses' Health Study 3) was conducted from June 1, 2010, to April 1, 2022, in 18 376 premenopausal, nonpregnant female nurses aged 19 to 44 years.

Main Outcomes and Measures

Pregnancy intention and pregnancy status were assessed at baseline and approximately every 3 to 6 months thereafter. Cox proportional hazards regression models were used to estimate the association between pregnancy intention and pregnancy incidence.

Results

A total of 18 376 premenopausal, nonpregnant women (mean [SD] age, 32.4 [6.5] years) participated in the study. At baseline, 1008 women (5.5%) were trying to conceive, 2452 (13.3%) were contemplating pregnancy within 1 year, and the remaining 14 916 (81.2%) were neither trying to conceive nor thought they would be pregnant within 1 year. A total of 1314 pregnancies were documented within 12 months of pregnancy intention assessment. The cumulative incidence of pregnancy was 38.8% in women actively trying to conceive (median [IQR] time to pregnancy, 3.3 [1.5-6.7] months), 27.6% in women contemplating pregnancy (median [IQR] time to pregnancy, 6.7 [4.2-9.3] months), and 1.7% in women neither trying to conceive nor contemplating pregnancy (median [IQR] time to pregnancy, 7.8 [5.2-10.5] months) among those who became pregnant. Women who were actively trying to conceive were 23.1 times (95% CI, 19.5-27.4 times) and women who were contemplating pregnancy were 13.0 times (95% CI, 11.1-15.2 times) more likely to conceive within 12 months than women who were neither attempting nor contemplating pregnancy. Among women contemplating pregnancy at baseline who did not get pregnant during follow up, 18.8% were actively trying and 27.6% were not trying by 12 months. Conversely, only 4.9% of women neither trying to conceive nor contemplating pregnancy within 1 year at baseline changed pregnancy intention during follow up.

Conclusions and Relevance

In this cohort study of reproductive-aged nurses in North America, pregnancy intention was highly fluid among women who were contemplating pregnancy but relatively stable among women trying to conceive and women who were neither trying to conceive nor contemplating pregnancy. Pregnancy intention was strongly associated with pregnancy incidence, but the median time to pregnancy points to a relatively short time window to initiate preconception care.

Time to pregnancy and perinatal outcomes in a cohort of spontaneous pregnancies

BACKGROUND

Obstetric and perinatal outcomes depend not only on care during pregnancy, as there is an increasing evidence of their relationship with preexisting conditions. Woman's age and time to pregnancy (TTP) have been related to the prognosis in reproductive success, but TTP could influence fetal well-being and newborn. According to the World Health Organization, 48 million couples have subfertility globally.

METHODS

We analyzed the relationship between TTP and obstetric (premature labor, preeclampsia…), labor (type of delivery, postpartum hemorrhage…), and neonatal outcomes (low birth weight…) in a cohort of 190 spontaneous gestations. Subfertility is a disease defined by the failure to achieve a pregnancy after 12 months of regular unprotected sexual intercourse.

RESULTS

TTP was >12 months in 23.1 % (95 % CI = 17.57-29.55), however, no correlation was found with the perinatal outcomes (p = 0.24). We observed that 45.2 % of subfertile women had obstetric complications, 13.2 % labor complications, and 34.2 % neonatal complications, whereas non-subfertile women had 29.4 %, 21.0 %, and 21.0 %, respectively. Half of pregnancies have at least one adverse outcome, and obstetric complications were the most frequent.

CONCLUSION

Subfertility condition may appear in up to a fifth of our couples. Subfertility may behave as a mild risk factor for adverse perinatal outcomes. Obstetric or perinatal complication may be expected in up to half of the cases. Subfertile women ≥ 35 years of age have a 3-fold increase in their risk of having an obstetric complication when compared to non-subfertile women of the same age.

History of infertility and pregnancy outcomes in Project Viva: a prospective study

Background

Infertility has been associated with the risk of adverse pregnancy outcomes. It is not clear whether infertility and underlying causes of infertility or the use of medically assisted reproduction (MAR) therapies are responsible for the observed associations. In this study, we aimed to evaluate the association of history of infertility with pregnancy outcomes and identify whether the associations, if present, differed by subgroups defined by the use of MAR.

Methods

Prospective study of 2201 pregnant women from the Boston-area Project Viva cohort. The exposure was history of infertility based on self-reported time to pregnancy ≥12 mo (or ≥ 6 mo if ≥35 y) or use of MAR; a diagnosis of infertility or claims for infertility treatments from medical records. The outcomes included: gestational glucose tolerance (gestational diabetes, impaired glucose tolerance, isolated hyperglycemia vs. normoglycemia), hypertensive disorders (gestational hypertension/preeclampsia vs. normotension), gestational weight gain (inadequate/excessive vs. adequate), systolic (SBP) and diastolic blood pressure, birthweight-for-gestational age z-score (tertile 2 and 3 vs. 1), preterm birth (<37 vs. ≥37 weeks at delivery), and birth outcome (pregnancy loss vs. live birth). We performed linear and logistic/multinomial regression analyses adjusted for age, race/ethnicity, age at menarche, pre-pregnancy BMI, and prenatal smoking.

Results

Mean (SD) age was 32.0 (5.0) years, and 18.8% of women had history of infertility, 32.6% of whom used MAR. SBP across pregnancy was 0.72 mmHg higher in women with vs. without infertility (95% CI 0.02, 1.42). The associations were stronger among women who used MAR (β 1.32 mmHg, 95% CI 0.21, 2.44), especially among those who used gonadotropins or gonadotropin-releasing hormone [GnRH] agonists (β 1.91 mmHg, 95% CI 0.48, 3.35). Other outcomes were not associated with history of infertility.

Conclusions

A history of infertility was associated with higher SBP during pregnancy, with stronger associations among those who used gonadotropins or GnRH agonists. Future studies are needed to confirm these findings and determine their clinical implications.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04885-8.

The current situation and future directions for the study on time-to-pregnancy: a scoping review

Introduction

As problems associated with infertility and population aging increase, there is a growing interest in the factors that cause a decline in human fertility. Time-to-pregnancy (TTP) is a good indicator with which to reflect human fecundability. Here, we present a comprehensive overview of this topic.

Methods

Relevant qualitative and quantitative studies were identified by searching the Web of science and PubMed electronic databases. We included all literature, written in English, from inception to the 10th April 2021 providing the focus was on TTP. We conducted a narrative synthesis using thematic analysis.

Results

Traditional TTP-related study protocols include prospective and retrospective cohorts that provide a wealth of data to reveal potential influences on TTP. Thus far, a variety of factors have been shown to be associated with TTP in couples preparing for pregnancy, including basic demographic characteristics, menstrual status, chronic disease status, environmental endocrine disruptor exposure, and lifestyles. However, there are inevitable epidemiological bias in the existing studies, including recall bias, selection bias and measurement bias. Some methodological advances have brought new opportunities to TTP research, which make it possible to develop precision interventions for population fertility. Future TTP studies should take advantage of artificial intelligence, machine learning, and high-throughput sequencing technologies, and apply medical big data to fully consider and avoid possible bias in the design.

Conclusion

There are many opportunities and future challenges for TTP related studies which would provide a scientific basis for the “precise health management” of the population preparing for pregnancy.

As the problems of infertility and population aging increase, there is a growing interest in the factors that cause a decline in human fertility. Time-to-pregnancy (TTP) is a good indicator with which to reflect human fecundability, and a longer TTP is known to reflect a reduction in fertility. Many original studies, with different designs, have used TTP to explore the factors that might influence fertility, including basic demographic characteristics, chronic disease status, environmental endocrine disruptor exposure, and lifestyles. However, much of the existing evidence is inconsistent and limited by various types of bias. This review provides a synopsis of recent TTP studies, and highlights new opportunities and future challenges.

Maternal fluoride exposure, fertility and birth outcomes: The MIREC cohort

OBJECTIVE

Fluoride exposure >1.5 mg/L from water has been associated with adverse pregnancy and birth outcomes. Little is known, however, about the effect of fluoride at levels consistent with water fluoridation (i.e., 0.7 mg/L) on pregnancy and birth outcomes. We examined the relationship between maternal fluoride exposure, fertility, and birth outcomes in a Canadian pregnancy cohort living in areas where municipal drinking water fluoride concentrations ranged from 0.04 to 0.87 mg/L.

METHODS

Using data from the Maternal-Infant Research on Environmental Chemicals (MIREC) study, we estimated fluoride exposure during pregnancy using three different metrics: (1) maternal urinary fluoride concentrations standardized for specific gravity (MUF_SG) and averaged across all three trimesters (N = 1566), (2) water fluoride concentration (N = 1370), and (3) fluoride intake based on self-reported consumption of water, coffee, and tea, adjusted for body weight (N = 1192). Data on fertility, birth weight, gestational age, preterm birth, and small-for-gestational age (SGA) were assessed. We used multiple linear regression to examine associations between fluoride exposure, birth weight and gestational age, and logistic regression to examine associations with fertility, preterm birth, and SGA, adjusted for relevant covariates.

RESULTS

Median (IQR) MUF_SG was 0.50 (0.33-0.76) mg/L, median water fluoride was 0.52 (0.17-0.64) mg/L, and median fluoride intake was 0.008 (0.003-0.013) mg/kg/day. MUF_SG, water fluoride concentrations, and fluoride intake were not significantly associated with fertility, birth weight, gestational age, preterm birth, or SGA. Fetal sex did not modify any of the associations.

CONCLUSION

Fluoride exposure during pregnancy was not associated with fertility or birth outcomes in this Canadian cohort.

Nitrate in Drinking Water and Time to Pregnancy or Medically Assisted Reproduction in Women and Men: A Nationwide Cohort Study in the Danish National Birth Cohort

Purpose

No studies have investigated if drinking water nitrate affects human fecundity. Experimental studies point at detrimental effects on fetal development and on female and male reproduction. This cohort study aimed to explore if female and male preconception and long-term exposure to nitrate in drinking water was associated with fecundability measured as time to pregnancy (TTP) or use of medically assisted reproduction (MAR) treatment.

Methods

The study population consisted of pregnant women recruited in their first trimester in 1996–2002 to the Danish National Birth Cohort. Preconception drinking-water nitrate exposure was estimated for the pregnant women (89,109 pregnancies), and long-term drinking water nitrate exposure was estimated from adolescence to conception for the pregnant women (77,474 pregnancies) and their male partners (62,000 pregnancies) by linkage to the national drinking water quality-monitoring database Jupiter. Difference in risk of TTP >12 months or use of MAR treatment between five exposure categories and log-transformed continuous models of preconception and long-term nitrate in drinking water were estimated. Binominal regression models for risk ratios (RR) were adjusted for age, occupation, education, population density, and lifestyle factors.

Results

Nitrate in drinking water (median preconception exposure: 1.9 mg/L; median long-term exposure: 3.3 mg/L) was not associated with TTP >12 months or use of MAR treatment, neither in the categorical nor in the continuous models.

Conclusion

We found no association between preconception or long-term exposure to drinking water nitrate and fecundability.

Trends in time-to-pregnancy in the USA: 2002 to 2017

STUDY QUESTION

Has there been there a temporal change in time-to-pregnancy (TTP) in the USA.

SUMMARY ANSWER

Overall, TTP was stable over time, but a longer TTP for women over 30 and parous women was identified.

WHAT IS KNOWN ALREADY

Fertility rates in the USA have declined over the past several years. Although these trends have been attributed to changing reproductive intentions, it is unclear whether declining fecundity (the biologic ability to reproduce measured by TTP in the current report) may also play a role. Indeed, trends based on declining sperm quality and higher utilisation of infertility treatment suggest fecundity may be falling.

STUDY DESIGN, SIZE, DURATION

This cross-sectional survey data from the National Survey of Family Growth was administered from 2002 to 2017. The surveys are based on nationally representative samples of reproductive-aged women in the USA. Interviews were conducted in person or through computer-assisted self-administration of sensitive questions.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study included women who self-reported time spent trying to become pregnant allowing utilisation of the current duration approach to estimate the total duration of pregnancy attempt (i.e. TTP). In all, 1202 participants were analysed over each study period. To estimate a TTP distribution overall and by parity, we used a piecewise constant proportional hazards model that accounts for digit preference. Accelerated-failure-time regression models, which were weighted to account for the sampling design, were used to estimate time ratios (TRs). Models were adjusted for age, BMI, race, education, relationship status, parity, pelvic inflammatory disease treatment and any reproductive problems.

MAIN RESULTS AND THE ROLE OF CHANCE

Of the participants analysed, the average age was 31.8 and BMI was 28.6, which was similar across the survey periods. Relationship status was the only demographic characteristic that changed over time. All other variables remained constant across the study periods. Overall, TRs comparing TTP between 2002 and 2017 increased slightly (TR: 1.02, 95% CI: 0.99, 1.04). When stratified by parity, parous women had a longer TTP over the later years of the study (TR: 1.04, 95% CI: 1.01, 1.06). TTP remained constant for nulliparous women. Similarly, TTP also increased over time for women over age thirty (TR: 1.02, 1.00, 1.05) but not for women under age thirty.

LIMITATIONS, REASONS FOR CAUTION

Small changes in data collection over time may have impacted the findings. We accounted for this in sensitivity analyses using imputed data. Overall, TRs were slightly attenuated using the imputed data, but represented similar patterns to the original data. Results for parous women and women over 30 remained consistent in the sensitivity analyses.

WIDER IMPLICATIONS OF THE FINDINGS

Consistent with reports of falling fertility rates and sperm counts, this study suggests parous and older couples in the USA may be taking longer to become pregnant. Although trends were suggestive of a small overall increase in TTP, particularly for parous women and women over age thirty, additional data are needed to attempt to understand these trends given the societal, economic and public health implications related to fecundity.

STUDY FUNDING/COMPETING INTEREST(S)

Funding was provided by National Institutes of Health grant R03HD097287 to A.C.M. There are no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Reproductive Health Risks Associated with Occupational and Environmental Exposure to Pesticides

A marked reduction in fertility and an increase in adverse reproductive outcomes during the last few decades have been associated with occupational and environmental chemical exposures. Exposure to different types of pesticides may increase the risks of chronic diseases, such as diabetes, cancer, and neurodegenerative disease, but also of reduced fertility and birth defects. Both occupational and environmental exposures to pesticides are important, as many are endocrine disruptors, which means that even very low-dose exposure levels may have measurable biological effects. The aim of this review was to summarize the knowledge collected between 2000 and 2020, to highlight new findings, and to further interpret the mechanisms that may associate pesticides with infertility, abnormal sexual maturation, and pregnancy complications associated with occupational, environmental and transplacental exposures. A summary of current pesticide production and usage legislation is also included in order to elucidate the potential impact on exposure profile differences between countries, which may inform prevention measures. Recommendations for the medical surveillance of occupationally exposed populations, which should be facilitated by the biomonitoring of reduced fertility, is also discussed.

Association between exposure to airborne particulate matter less than 2.5 μm and human fecundity in China

BACKGROUND

Whether exposure to airborne particulate matter less than 2.5 μm (PM_2.5) could impact human fecundity is unclear. We aimed to evaluate the potential impact of PM_2.5 exposure on time to pregnancy (TTP) and the prevalence of infertility in the general Chinese population.

METHOD

We collected reproductive information, sociodemographic characteristics, and lifestyle data of 10,211 couples at risk of pregnancy from a large-scale community-based fertility survey in China. Then, we estimated each participant's 1-year, 3-year, and 5-year average PM_2.5 exposure levels based on remote sensing information. After adjusting for demographic, lifestyle, and environmental co-variables, discrete-time Cox regression models were used to estimate the fecundability odds ratio (FOR) per 10 μg/m³ change of PM_2.5. We also estimated the odds ratio (OR) of infertility per 10 μg/m³ change of PM_2.5, using logistic regression models.

FINDINGS

Among the 10,211 couples, 6,875 (67%) had conceived spontaneously, with a median TTP of 5 months (interquartile range: 2-10 months). The median PM_2.5 exposure was 56.8 μg/m³, with a wide range of 9.2-93.5 μg/m³. In Cox regression models, each increase of 10 μg/m³ in the 1-year average PM_2.5 exposure was associated with a significant decrease in fecundity by 11% (FOR: 0.89; 95% confidence interval [CI]: 0.86-0.92). In logistic regression models, it was also associated with an 20% increased likelihood of infertility (OR: 1.20; 95% CI: 1.13-1.27).

CONCLUSION

PM_2.5 exposure was associated with reduced human fecundity, presented by a longer TTP and higher odds of infertility, which might explain the increased infertility rates in areas with heavy PM_2.5 pollution.

Maternal age at delivery and fertility of the next generation

BACKGROUND

While most known causes of infertility relate to the health of the woman and/or her partner, questions have been raised regarding the possible contributions of transgenerational or epigenetic factors.

OBJECTIVE

The goal of this hypothesis-generating work was to examine whether Generation 1's (G1's) age at the delivery of G2 (Generation 2) was associated with G2's fertility in later life.

METHODS

We conducted a retrospective cohort study of women (G2s) recruited online in 2016. A questionnaire queried G2s regarding demographics and fertility. The primary exposure was G1's age at G2's birth. Outcome measures included the following: 12-month infertility, time to pregnancy, and childlessness. The adjusted relative risk (RR) of G2 infertility and childlessness by G1 age at G2's birth was estimated through a modified Poisson regression approach. The fecundity odds ratio (FOR) for the association between G1's age at G2 birth and time to pregnancy for G2 was estimated by discrete-time survival models, with complementary log-log link.

RESULTS

A total of 2,854 women enrolled. We found no association between G1 age at G2's birth and G2 infertility. Being born to a G1 aged 15-19 years was associated with a longer time to pregnancy for G2 (FOR 0.84, 95% confidence interval 0.72, 0.99), relative to being born to a G1 aged 20-24 years. We observed the suggestion of a possible increased risk of childlessness among G2s born to older G1s, but the estimate was imprecise.

CONCLUSIONS

While being born to a G1 who was 15-19 years old was associated with an increase in G2 time to pregnancy, we found no association between G1 age at G2's birth and infertility and only the suggestion of a modest association with childlessness. These data suggest a possible subtle effect of G1 age at G2's birth on G2 fertility, which warrants further study.

Changes in Behavior with Increasing Pregnancy Attempt Time: A Prospective Cohort Study

BACKGROUND

The extent to which couples change their behaviors with increasing pregnancy attempt time is not well documented.

METHODS

We examined change in selected behaviors over pregnancy attempt time in a North American preconception cohort study. Eligible females were ages 21-45 years and not using fertility treatment. Participants completed baseline and bimonthly follow-up questionnaires for up to 12 months or until pregnancy.

RESULTS

Among 3,339 females attempting pregnancy for 0-1 cycles at enrollment, 250 contributed 12 months of follow-up without conceiving. Comparing behaviors at 12 months versus baseline, weighted for loss-to-follow-up, we observed small-to-moderate reductions in mean caffeine intake (-19.5 mg/day, CI = -32.7, -6.37), alcohol intake (-0.85 drinks/week, CI = -1.28, -0.43), marijuana use (-3.89 percentage points, CI = -7.33, 0.46), and vigorous exercise (-0.68 hours/week, CI = -1.05, -0.31), and a large increase in activities to improve conception chances (e.g., ovulation testing) (21.7 percentage points, CI = 14.8, 28.6). There was little change in mean cigarette smoking (-0.27 percentage points, CI = -1.58, 1.04), perceived stress scale score (-0.04 units, CI = -0.77, 0.69), or other factors (e.g., sugar-sweetened soda intake, moderate exercise, intercourse frequency, and multivitamin use), but some heterogeneity within subgroups (e.g., 31% increased and 32% decreased their perceived stress scores by ≥2 units; 14% reduced their smoking but none increased their smoking by ≥5 cigarettes/day).

CONCLUSIONS

Although many behaviors changed with increasing pregnancy attempt time, mean changes tended to be modest for most variables. The largest differences were observed for the use of caffeine, alcohol, and marijuana, and methods to improve conception chances.

Stressful life events, the incidence of infertility, and the moderating effect of maternal responsiveness: a longitudinal study

Although the association between stress and poor reproductive health is well established, this association has not been examined from a life course perspective. Using data from the National Longitudinal Survey of Youth 1997 cohort (N = 1652), we fit logistic regression models to test the association between stressful life events (SLEs) (e.g., death of a close relative, victim of a violent crime) during childhood, adolescence, and early adulthood and later experiences of infertility (inability to achieve pregnancy after 12 months of intercourse without contraception) reported by female respondents. Because reactions to SLEs may be moderated by different family life experiences, we stratified responses by maternal responsiveness (based on the Conger and Elder Parent-Youth Relationship scale) in adolescence. After adjusting for demographic and environmental factors, in comparison to respondents with one or zero SLEs, those with 3 SLEs and ≥ 4 SLEs had 1.68 (1.16, 2.42) and 1.88 (1.38, 2.57) times higher odds of infertility, respectively. Respondents with low maternal responsiveness had higher odds of infertility that increased in a dose-response manner. Among respondents with high maternal responsiveness, only those experiencing four or more SLEs had an elevated risk of infertility (aOR = 1.53; 1.05, 2.25). In this novel investigation, we demonstrate a temporal association between the experience of SLEs and self-reported infertility. This association varies by maternal responsiveness in adolescence, highlighting the importance of maternal behavior toward children in mitigating harms associated with stress over the life course.

The association between preconception body mass index and subfertility among Hispanic and non-Hispanic women: A cross-sectional study from Utah's Pregnancy Risk Assessment Monitoring System survey (2012-2015)

OBJECTIVE

To investigate the association between pre-pregnancy body mass index (BMI) and subfertility within a population-based cohort, exploring Hispanic ethnicity as a potential effect modifier.

METHODS

We used cross-sectional study data from the Utah Pregnancy Risk Assessment Monitoring System from 2012-2015. Relationships between maternal pre-pregnancy BMI and subfertility were evaluated via Poisson regression models with robust error variance, accounting for the stratified survey sampling. Preconception BMI was analyzed continuously and categorically. Women's subfertility was defined via self-report in two ways: 1) time trying to achieve pregnancy; and 2) report of using fertility-related drugs/medical procedures.

RESULTS

The median age was 27.0; 18.8% were obese, and 15.9% were Hispanic. Women with preconception obesity (BMI>30kg/m²), compared to normal weight women (18.4kg/ m²<BMI<25kg/m²) had a 1.85 (95% CI 1.43, 2.38) higher adjusted prevalence ratio (aPR) for having subfertility defined by time trying and a 1.73 (95% CI 1.20, 2.32) higher aPR for receiving fertility-enhancing drugs/medical procedures. Continuous models indicated a linear relationship between BMI and subfertility (aPR 1.04, 95% CI 1.03, 1.06 for time trying; and 1.06, 95% CI 1.03, 1.10 for receiving fertility-enhancing drugs/medical procedures).

CONCLUSIONS

Obese women, but not underweight or overweight women, reported higher subfertility than normal-weight women. Findings among this cohort of at-risk new mothers, oversampled on low education and birth weight and comprised of higher than the national average of Hispanics, indicated a dose-response relationship between obesity and subfertility.

IMPLICATIONS

Our findings highlight the importance of population-oriented obesity prevention for at-risk women with intentions to conceive.

Preeclampsia Is Associated With Increased Preclinical Carotid Atherosclerosis in Women With Type 1 Diabetes

PURPOSE

Although preeclampsia (PE) is a well-established cardiovascular risk factor (CVRF) in the general population, its role in type 1 diabetes (T1D) has been scarcely studied. We assessed the association between PE and preclinical atherosclerosis in T1D.

METHODS

We recruited 112 women without cardiovascular disease and last pregnancy ≥5 years before: (1) T1D and previous PE (T1D+/PE+; n = 28); (2) T1D without preeclampsia (T1D+/PE-; n = 28); (3) previous PE without T1D (T1D-/PE+; n = 28); and (4) controls (without T1D or PE; T1D-/PE-; n = 28). Groups were matched by age, several CVRFs, and diabetes duration and retinopathy (in T1D participants). Carotid intima-media thickness (IMT) and the presence of plaque (IMT ≥ 1.5 mm) were assessed by standardized ultrasonography protocol.

RESULTS

Mean age of the participants was 44.9 ± 7.8 years (14.3% hypertension and 21.4% active smokers). Groups including T1D (T1D+/PE+ and T1D+/PE-) more frequently presented hypertension and statin treatment (23.2% vs 5.4% and 37.5% vs 8.9%; respectively; P < 0.01), without differences in other CVRFs. Carotid plaques were observed in 20.5%. In multivariate models adjusted for age, CVRF, and statins, both T1D and PE showed a similar impact on the presence of plaque, with odds ratios (95% confidence interval), 5.45 (1.36-21.9) and 4.24 (1.04-17.3), respectively. Both entities showed an additive effect when combined, both in common carotid-IMT (T1D+/PE- or T1D-/PE+, β = 0.198; T1D+/PE+, β = 0.297) and in the presence of plaque (8.53 [1.07-68.2] and 28.1 [2.67-296.4], respectively).

CONCLUSIONS

Previous PE was independently associated with preclinical atherosclerosis in T1D. Further studies are needed to ascertain its usefulness for stratifying risk in T1D women.

Uterine fibroids increase time to pregnancy: a cohort study

Objectives: The primary purpose of the study was to investigate a possible association between uterine fibroids and time to pregnancy (TTP), and, secondly, to explore the effect of myomectomy on TTP.Methods: This historical cohort study used data from the Danish National Birth Cohort and the Danish National Patient Registry. The study population consisted of 86,323 women with 92,696 pregnancies. The main outcome was TTP; groups were compared using a binary outcome: TTP >12 months or TTP ≤12 months.Results: Women who had a fibroid diagnosis code before attempting to conceive (n = 92) had an increased risk of TTP >12 months compared with women without a fibroid diagnosis code (n = 87,358) (adjusted odds ratio [OR] 1.67; 95% confidence interval [CI] 1.05, 6.68). Women who had a fibroid diagnosis code after pregnancy (n = 963) also had an increased risk of TTP >12 months compared with women without a fibroid diagnosis code (adjusted OR 1.24; 95% CI 1.04, 1.47).Conclusion: We found an association between having a uterine fibroid diagnosis code and TTP >12 months. We were not able to make a valid assessment of the effect of myomectomy on TTP.

Association between peri-conceptional bisphenol A exposure in women and men and time to pregnancy-The HOPE study

BACKGROUND

Bisphenol A (BPA) is a non-persistent endocrine-disrupting chemical with nearly ubiquitous, involuntary exposure. Previous studies have shown that BPA causes reproductive dysfunction in animal models, but there are limited data regarding the effects of BPA exposure on time to pregnancy (TTP) in humans.

OBJECTIVE

To evaluate whether peri-conceptional BPA exposure of women and men is associated with couples' TTP.

METHODS

A total of 164 heterosexual couples (164 women; 163 men) who have available BPA information as well as time to pregnancy from the Home Observation of Peri-conceptional Exposures (HOPE) Study were included and were followed up to 12 months. Women collected first-morning urine samples starting at the beginning of the fertile window and continued until the onset of menses or 18 days after the estimated day of ovulation (EDO+18 days). The time to pregnancy (TTP) after the enrolment was self-reported and used for the analysis. Discrete-time Cox proportional hazards models were performed to generate fecundability odds ratio (FOR) between BPA and TTP after adjusting for education and age, accounting for right censoring and prior number of cycles trying to conceive.

RESULTS

Among 164 couples, 125 couples became pregnant during the study. There was no association between TTP and peri-conceptional BPA exposure for both men (FOR 1.02, 95% CI 0.72, 1.47) and women (FOR 1.07, 95% CI 0.75, 1.53) after adjusting for education and age.

CONCLUSIONS

No association was found between peri-conceptional BPA exposure and fecundability in this preconception cohort of relatively young, healthy pregnancy planners.

Administration of antineoplastic drugs and fecundity in female nurses

BACKGROUND

We examined the association between the administration of antineoplastic drugs (AD) and fecundity among female nurses.

METHODS

AD administration and use of exposure controls (EC) such as gloves, gowns, and needleless systems were self-reported at baseline among 2649 participants of the Nurses' Health Study 3, who were actively attempting pregnancy. Every 6 months thereafter, the nurses reported the current duration of their pregnancy attempt. Multivariable accelerated failure time models were used to estimate time ratios (TR) and 95% confidence intervals (CI) adjusted for age, race, body mass index, smoking, marital status, hours of work, and other occupational risk factors.

RESULTS

Mean (standard deviation) age and BMI at baseline were 30.7 years (4.7) and 26.0 kg/m² (6.4). Forty-one percent of nurses reported ever administering AD; 30% only in the past and 11% currently. The former administration of AD (TR = 1.02, 95% CI, 0.93-1.12) was unrelated to the ongoing duration of pregnancy attempt. Among nurses currently administering AD, those who had administered AD for 6 years and above had a 27% (95% CI, 6%-53%) longer duration of pregnancy attempt than nurses who never handled ADs in unadjusted analyses. This difference disappeared in multivariable analyses (TR = 1.01, 95% CI, 0.85-1.21). 93% (n = 270) of the nurses currently administering ADs reported consistent use of EC. These nurses had a similar median duration of pregnancy attempt to those who never handled AD (TR = 1.00, 95% CI, 0.87-1.15).

CONCLUSIONS

Administration of ADs did not appear to have an impact on fecundity in a cohort of nurses planning for pregnancy with a high prevalence of consistent ECs. Our results may not be generalizable to women who are less compliant with PPE use or with less availability to ECs. Therefore, it is possible that we did not observe an association between occupational exposure to AD and reduced fecundity because of lower exposure due to the more prevalent use of effective ECs.

Fecundity and Infertility Among Women with Disabilities in the United States

Background: Knowledge of fecundity and infertility in women with a disability (WWD) is limited. This study aims to compare the fecundity and infertility experiences of women with a self-identified disability, in domains of sensory (hearing and vision loss), cognitive (difficulty concentrating, remembering, and making decisions), and physical (difficulty walking or climbing stairs) disabilities, with those without a self-identified disability. Materials and Methods: Cross-sectional survey data from the National Survey of Family Growth (NSFG), 2011-2015, were analyzed. A final analytic sample of 383 women from the NSFG, aged 18-44 years, was included to study the fecundity rates of WWD and women without a disability, using the current duration approach. Results: Fecundity hazard ratios (FHRs) and the proportion of women experiencing infertility after 12 months of actively attempting pregnancy were reported for the comparison group and by each disability type. Women with a self-identified cognitive disability experienced significant decreases in fecundity (FHR = 0.56; 95% confidence interval [CI]: 0.30-0.88) when adjusting for age, education level, parity, living in a metropolitan area, and infertility services. Furthermore, the estimated proportion of infertile women without a disability was 0.38 (95% CI: 0.23-0.62) versus 0.51 (95% CI: 0.34-0.72) for women with a self-identified cognitive disability. Conclusions: Women with a self-identified cognitive disability experienced significant decreases in fecundity.

Exposure to tetrachloroethylene-contaminated drinking water and time to pregnancy

BACKGROUND

The synthetic solvent tetrachloroethylene (PCE), commonly used in dry cleaning operations, is a human neurotoxicant and carcinogen. However, its effect on reproduction is poorly understood, as prior studies have been limited to small occupational cohorts. We examined the association between PCE exposure from contamination of the public drinking water supply and time-to-pregnancy (TTP) in a cohort of mothers from Cape Cod, Massachusetts.

METHODS

The Cape Cod Family Health Study is a retrospective cohort study designed to examine the reproductive and developmental health effects of exposure to PCE-contaminated drinking water. Our analysis included 1565 women who reported 3826 planned pregnancies from 1949 to 1990. Women completed self-administered questionnaires that ascertained TTP for each of her pregnancies, regardless of the outcome, as well as residential history and demographic information. We utilized EPANET water distribution system modeling software and a leaching and transport model to assess PCE exposure for each pregnancy. We used log-binomial regression models to estimate relative risks (RR) and 95% confidence intervals (CI), adjusting for potential confounders. We performed a probabilistic bias analysis to examine the effect of outcome misclassification on our results.

RESULTS

Any cumulative PCE exposure before pregnancy was associated with a 15% reduction in risk of TTP > 12 months (RR = 0.85, 95% CI: 0.70, 1.03). However, women with the highest average monthly PCE exposure around the time of the pregnancy attempt (≥ 2.5 g) had increased risk of TTP > 12 months (RR = 1.36, 95% CI: 1.06, 1.76).

CONCLUSIONS

We found little evidence for long-term, cumulative adverse effects of PCE exposure on TTP, but high levels of PCE exposure around the time of the pregnancy attempt were associated with longer TTP. These associations may be underestimated due to the exclusion of unsuccessful pregnancy attempts from our study population, and may be biased by outcome and exposure misclassification given the long-term recall of TTP and use of a leaching and transport model to estimate PCE exposure.

Childhood cardiovascular health and subfertility: the Bogalusa Heart Study

BACKGROUND

Although childhood cardiovascular risk can contribute to adult cardiovascular disease, and fertility and adult cardiovascular health are linked, the association between early-life cardiovascular risk and female infertility has not been studied.

METHODS

A total of 1799 women participated in the Babies substudy of the Bogalusa Heart Study. Systolic blood pressure (SBP), diastolic blood pressure (DBP), low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides, glucose, and insulin were age-standardized and examined as predictors of self-reported fertility difficulties using multivariable logistic regression with adjustment for confounders. Polycystic ovarian syndrome (PCOS) was assessed via a report of diagnosis and symptoms, using a validated questionnaire.

RESULTS

Women with a history of PCOS were more likely to report fertility difficulties. Childhood and adolescent cardiovascular risk factors were generally not associated with fertility indicators, although childhood LDL (aOR 1.38 per one-SD increase, 0.97-1.96) and total cholesterol (aOR 1.49, 1.06-2.11) were raised in those who never became pregnant. Pre-pregnancy risk SBP (overall fertility, aOR 1.49, 1.00-2.23) and glucose levels (ever tried but unable, aOR 2.65, 1.39-5.06) were associated with an increased risk of some infertility indicators. These results were largely unaffected by exclusion of women with PCOS.

CONCLUSION

Some childhood and pre-pregnancy cardiovascular risk factors are associated with adult subfertility.

Shorter Time to Pregnancy With Increasing Preconception Carotene Concentrations Among Women With 1-2 Previous Pregnancy Losses

Although maternal nutrition may affect fecundity, associations between preconception micronutrient levels and time to pregnancy (TTP) have not been examined. We assessed the relationship between preconception fat-soluble micronutrient concentrations and TTP among women with 1-2 prior pregnancy losses. This was a prospective cohort study of 1,228 women set within the Effects of Aspirin in Gestation and Reproduction (EAGeR) Trial (United States, 2007-2011), which assessed the association of preconception-initiated daily low-dose aspirin with reproductive outcomes. We measured preconception levels of zeaxanthin, cryptoxanthin, lycopene, α- and β-carotene, and α- and γ-tocopherol in serum. We used discrete Cox regression models, accounting for left-truncation and right-censoring, to calculate fecundability odds ratios and 95% confidence intervals. The models adjusted for age, body mass index, race, smoking, alcohol, physical activity, income, vitamin use, cholesterol, treatment arm, and study site. Serum α-carotene levels (per log unit (μg/dL) increase, fecundability odds ratio (FOR) = 1.17, 95% confidence interval (CI): 1.00, 1.36) and serum α-carotene concentrations at or above the US average (2.92 μg/dL) versus below the average (FOR = 1.21, 95% CI: 1.02, 1.44) were associated with shorter TTP. Compared with levels below the US average (187 μg/dL), γ-tocopherol concentrations at or above the average were associated with longer TTP (FOR = 0.83, 95% CI: 0.69, 1.00). The potential for these nutrients to influence fecundability deserves further exploration.

Is human fecundity changing? A discussion of research and data gaps precluding us from having an answer

Fecundity, the biologic capacity to reproduce, is essential for the health of individuals and is, therefore, fundamental for understanding human health at the population level. Given the absence of a population (bio)marker, fecundity is assessed indirectly by various individual-based (e.g. semen quality, ovulation) or couple-based (e.g. time-to-pregnancy) endpoints. Population monitoring of fecundity is challenging, and often defaults to relying on rates of births (fertility) or adverse outcomes such as genitourinary malformations and reproductive site cancers. In light of reported declines in semen quality and fertility rates in some global regions among other changes, the question as to whether human fecundity is changing needs investigation. We review existing data and novel methodological approaches aimed at answering this question from a transdisciplinary perspective. The existing literature is insufficient for answering this question; we provide an overview of currently available resources and novel methods suitable for delineating temporal patterns in human fecundity in future research.

Perfluoroalkyl Chemicals, Menstrual Cycle Length, and Fecundity: Findings from a Prospective Pregnancy Study

BACKGROUND

Perfluoroalkyl substances have been associated with changes in menstrual cycle characteristics and fecundity, when modeled separately. However, these outcomes are biologically related, and we evaluate their joint association with exposure to perfluoroalkyl substances.

METHODS

We recruited 501 couples from Michigan and Texas in 2005-2009 upon their discontinuing contraception and followed them until pregnancy or 12 months of trying. Female partners provided a serum sample on enrollment and completed daily journals on menstruation, intercourse, and pregnancy test results. We measured seven perfluoroalkyl substances in serum using liquid chromatography-tandem mass spectrometry. We assessed the association between perfluoroalkyl substances and menstrual cycle length using accelerated failure time models and between perfluoroalkyl substances and fecundity using a Bayesian joint modeling approach to incorporate cycle length.

RESULTS

Menstrual cycles were 3% longer comparing women in the second versus first tertile of perfluorodecanoate (PFDeA; acceleration factor [AF] = 1.03, 95% credible interval [CrI] = [1.00, 1.05]), but 2% shorter for women in the highest versus lowest tertile of perfluorooctanoic acid (PFOA; AF = 0.98, 95% CrI = [0.96, 1.00]). When accounting for cycle length, relevant covariates, and remaining perfluoroalkyl substances, the probability of pregnancy was lower for women in second versus first tertile of perfluorononanoate (PFNA; odds ratio [OR] = 0.6, 95% CrI = [0.4, 1.0]) although not when comparing the highest versus lowest (OR = 0.7, 95% CrI = [0.3, 1.1]) tertile.

CONCLUSIONS

In this prospective cohort study, we observed associations between two perfluoroalkyl substances and menstrual cycle length changes, and between select perfluoroalkyl substances and diminished fecundity at some (but not all) concentrations. See video abstract at, http://links.lww.com/EDE/B136.

Long-term Recall of Time to Pregnancy

BACKGROUND

Despite the widespread use of retrospectively reported time to pregnancy to evaluate fertility either as an outcome or as a risk factor for chronic disease, only two small studies have directly compared prospective data with later recall.

METHODS

The North Carolina Early Pregnancy Study (1982-1986) collected prospective time-to-pregnancy data from the beginning of participants' pregnancy attempt. In 2010, (24-28 years later) women were sent a questionnaire including lifetime reproductive history that asked about all prior times to pregnancy. Of the 202 women with prospective time-to-pregnancy data, 76% provided recalled time to pregnancy.

RESULTS

A lower proportion of women with times to pregnancy ≥3 cycles provided a recalled time to pregnancy than women with times to pregnancy <3 cycles. Also, high gravidity or parity was associated with a lower likelihood of providing a recalled time to pregnancy. Women with very short or very long times to pregnancy (1 cycle or ≥13 cycles) had good recall of time to pregnancy. Positive predictive values of 1 or ≥13 cycles were 73% and 68%, respectively, while positive predictive values for other categories of time to pregnancy ranged from 38% to 58%. The weighted kappa statistic for recalled versus prospective time to pregnancy was 0.72 (95% confidence interval: 0.65, 0.79).

CONCLUSIONS

Recalled time to pregnancy showed good agreement with prospective time to pregnancy. Informative missingness must be considered when imputing recalled time to pregnancy. Associations observed in future studies can be corrected for misclassification.

Parental health status and infant outcomes: Upstate KIDS Study

OBJECTIVE

To assess parental health status inclusive of infertility and infant outcomes.

DESIGN

Birth cohort with cross-sectional analysis of parental health status and infant outcomes.

SETTING

Not applicable.

PATIENT(S)

Parents (n = 4,886) and infants (n = 5,845) participating in the Upstate KIDS birth cohort.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Infertility was defined as [1] sexually active without contraception for 1+ years without pregnancy, [2] ever requiring ≥12 months to become pregnant, and [3] requiring ≥12 months for index pregnancy. Multivariable linear regression with generalized estimating equations estimated the change (β coefficient and 95% confidence interval [CI]) in infant outcomes (gestation, birthweight, length, head circumference, ponderal index) and relative to each disease, including infertility after adjusting for age, body mass index, and infertility treatment.

RESULT(S)

Prevalence of parental chronic diseases ranged from <1% to 19%, and 21% to 54% for infertility. Maternal hypertension was negatively associated with gestation (β, -0.64; 95% CI, -1.03, -0.25) and birthweight (-151.98; -262.30, -41.67) as was asthma and birthweight (-75.01; -130.40, -19.62). Maternal kidney disease was associated with smaller head circumference (-1.09; -2.17, -0.01), whereas paternal autoimmune disease was associated with larger head circumference (0.87; 0.15, 1.60). Infertility was negatively associated with birthweight (-62.18; -103.78, -20.58), length (-0.33; -0.60, -0.06), and head circumference (-0.35; -0.67, -0.03).

CONCLUSION(S)

Infertility was significantly associated with reduced infant size even after accounting for infertility treatment, although the magnitude of reduction varied by definition of infertility. Absence of pregnancy within a year of being at risk may be informative about health.

Brief Report: Plasma Concentrations of Perfluorooctane Sulfonamide and Time-to-pregnancy Among Primiparous Women

BACKGROUND

A previous study reported a negative association between perfluorooctane sulfonamide (PFOSA) concentrations and fecundability.

METHODS

We examined this association among women enrolled in the Norwegian Mother and Child Cohort Study (MoBa), in 2003-2004. This analysis was restricted to 451 primiparous women to avoid bias due to previous pregnancy. Self-reported time-to-pregnancy (TTP) and plasma were obtained around 18 weeks of gestation. Approximately half of the women had measurable PFOSA levels; missing values were multiply imputed. We used the logistic analogue of discrete-time survival analysis to examine the adjusted association between PFOSA, other perfluoroalkyl substances, and TTP.

RESULTS

The median-measured PFOSA concentration was 0.03 ng/ml (interquartile range = 0.02, 0.07). The age and body mass index-adjusted association between an interquartile distance increase in PFOSA and TTP was 0.91 (95% confidence interval = 0.71, 1.17). Imputation of missing PFOSA resulted in similar estimates. No association was observed with other perfluoroalkyl substances.

CONCLUSION

Based on a weakly decreased fecundability odds ratio, we found only limited support for an association between plasma PFOSA concentrations and TTP among primiparous women. See Video Abstract at http://links.lww.com/EDE/B79.

The Gulf oil spill, miscarriage, and infertility: the GROWH study

PURPOSE

To examine whether reported exposure to the Gulf oil spill (2010) was related to reproductive reported miscarriage or infertility.

METHODS

1524 women aged 18-45 recruited through prenatal and Women, Infant, and Children (WIC) clinics, and community events were interviewed about their experience of the oil spill and reproductive history. 1434 women had information on outcomes of at least one pregnancy, and 633 on a pregnancy both before and after the spill. Generalized estimating equations were used to examine the relationship between contact with oil and economic and social consequences of the spill with postponement of pregnancy, miscarriage, and infertility (time to pregnancy >12 months or reported fertility issues), with adjustment for age, race, BMI, smoking, and socioeconomic status. Results were compared for pregnancies occurring prior to and after the oil spill.

RESULTS

77 (5.1%) women reported postponing pregnancy due to the oil spill, which was more common in those with high contact with oil or overall high exposure (aOR 2.92, 95% CI 1.31-6.51). An increased risk of miscarriage was found with any exposure to the oil spill (aOR, 1.54, 95% CI 1.17-2.02). Fertility issues were more common in the overall most highly exposed women (aOR 1.88, 1.19-2.95), when the data were limited to those with pregnancies before and after. However, no particular aspect of oil spill exposure was strongly associated with the outcomes, and effects were almost as strong for pregnancies prior to the oil spill.

CONCLUSIONS

The oil spill appears to have affected reproductive decision-making. The evidence is not strong that exposure to the oil spill was associated with miscarriage or infertility.

Low-level arsenic exposure via drinking water consumption and female fecundity - A preliminary investigation

High level arsenic exposure is associated with reproductive toxicity in experimental and observational studies; however, few data exist to assess risks at low levels. Even less data are available to evaluate the impact of low level arsenic exposure on human fecundity. Our aim in this pilot study was a preliminary evaluation of associations between low level drinking water arsenic contamination and female fecundity. This retrospective study was conducted among women previously recruited to a hospital-based case-control study of spontaneous pregnancy loss in Timiṣ County, Romania. Women (n=94) with planned pregnancies of 5-20 weeks gestation completed a comprehensive physician-administered study questionnaire and reported the number of menstrual cycles attempting to conceive as the time to pregnancy (TTP). Drinking water samples were collected from residential drinking water sources and we determined arsenic levels using hydride generation-atomic absorption spectrometry (HG-AAS). Multivariable Cox-proportional hazards regression with Efron approximation was employed to evaluate TTP as a function of drinking water arsenic concentrations among planned pregnancies, adjusted for covariates. There was no main effect for drinking water arsenic exposure, yet the conditional probability for pregnancy was modestly lower among arsenic exposed women with longer TTPs, relative to women with shorter TTPs, and relative to unexposed women. For example, 1µg/L average drinking water arsenic conferred 5%, 8%, and 10% lower likelihoods for pregnancy in the 6th, 9th, and 12th cycles, respectively (P=0.01). While preliminary, our results suggest that low level arsenic contamination in residential drinking water sources may further impair fecundity among women with longer waiting times; however, this hypothesis requires confirmation by a future, more definitive study.

Occupational use of high-level disinfectants and fecundity among nurses

Objective This study aimed to examine the relationship between occupational use of high-level disinfectants (HLD) and fecundity among female nurses. Methods Women currently employed outside the home and trying to get pregnant (N=1739) in the Nurses' Health Study 3 cohort (2010-2014) were included in this analysis. Occupational exposure to HLD used to disinfect medical instruments and use of protective equipment (PE) was self-reported on the baseline questionnaire. Every six months thereafter women reported the duration of their ongoing pregnancy attempt. Multivariable accelerated failure time models were used to estimate time ratios (TR) and 95% confidence intervals (95% CI). Results Nurses exposed to HLD prior to and at baseline had a 26% (95% CI 8-47%) and 12% (95% CI -2-28%) longer median duration of pregnancy attempt compared to nurses who were never exposed. Among nurses exposed at baseline to HLD, use of PE attenuated associations with fecundity impairments. Specifically, women using 0, 1, and ≥2 types of PE had 18% (95% CI -7-49%), 16% (95% -3-39%), and 0% (95% -22-28%) longer median durations of pregnancy attempt compared to women who were never exposed. While the use of PE varied greatly by type (9% for respiratory protection to 69% for protective gloves), use of each PE appeared to attenuate the associations of HLD exposure with reduced fecundity. Conclusion Occupational use of HLD is associated with reduced fecundity among nurses, but use of PE appears to attenuate this risk.

Proximity to major roadways and prospectively-measured time-to-pregnancy and infertility

We aimed to study the potential impact of proximity to major roadways on time-to-pregnancy and infertility in couples attempting pregnancy in the Longitudinal Investigation of Fertility and Environment (LIFE) study (2005-2009), a population-based, prospective cohort study. Couples attempting pregnancy (n=500) were enrolled and followed prospectively until pregnancy or 12months of trying and 393 couples (78%) had complete data and full follow-up. Time-to-pregnancy was based on a standard protocol using fertility monitors, tracking estrone-3-glucuonide and luteinizing hormone, and pregnancy test kits to detect human chorionic gonadotropin (hCG). The fecundability odds ratio (FOR) and 95% confidence interval (CI) were estimated using proportional odds models. Infertility was defined as 12months of trying to conceive without an hCG pregnancy and the relative risk (RR) and 95% CI were estimated with log-binomial regression. Final models were adjusted for age, parity, study site, and salivary alpha-amylase, a stress marker. Infertile couples (53/393; 14%) tended to live closer to major roadways on average than fertile couples (689m vs. 843m, respectively) but the difference was not statistically significant. The likelihood of pregnancy was increased 3% for every 200m further away the couples residence was from a major roadway (FOR=1.03; CI=1.01-1.06). Infertility also appeared elevated at moderate distances compared to 1000m or greater, but estimates lacked precision. Our findings suggest that proximity to major roadways may be related to reductions in fecundity. Prospective data from larger populations is warranted to corroborate these findings.

Time-to-Pregnancy Associated With Couples' Use of Tobacco Products

INTRODUCTION

Previous studies suggest female smoking increases time-to-pregnancy (TTP), a couple-dependent reproductive outcome, while associations with male smoking are more ambiguous. Furthermore, despite small increases in smokeless tobacco use in the United States, no prior study has evaluated TTP among smokeless tobacco users.

METHODS

Using population-based sampling in 16 counties in Michigan and Texas, 501 couples discontinuing contraception to become pregnant were followed until positive pregnancy test or 12 months of trying. Participants were interviewed on lifetime and current cigarette, cigar, and chew/snuff (smokeless) use and provided blood samples for quantification of heavy metals and cotinine. Fecundability odds ratios (FORs) and 95% confidence intervals (95% CIs) were estimated, adjusted for demographics/lifestyle. FORs less than 1 reflect longer TTP.

RESULTS

Eleven percentage of females and 15% of males smoked cigarettes. Among men, 14% smoked cigars, 9% used snuff, and 2% used chew. Compared with never tobacco users, male (FOR: 0.41, 95% CI: 0.24, 0.68) and female (FOR: 0.53, 95% CI: 0.33, 0.85) smoking were individually associated with longer TTP; males' smoking remained significant (FOR: 0.46, 95% CI: 0.27, 0.79) when modeling partners together. Cadmium levels were higher in smokers than smokeless tobacco and never users; adjusting for cadmium attenuated the cigarette-TTP association, particularly among women. TTP was shorter among smokeless tobacco users relative to smokers (FOR: 2.86, 95% CI: 1.47, 5.57).

CONCLUSIONS

Compared with never users, smokeless tobacco did not alter TTP in our cohort; however, TTP was shorter compared with smokers. We observed longer TTP in male and female smokers; cadmium may partially contribute.

IMPLICATIONS

Both partners' preconception smoking contributed to longer TTP, highlighting the importance of both partners' lifestyles in healthy reproduction and underscores the need for couple-based preconception guidance. The male's contribution is a new finding. Higher cadmium levels may partially contribute to longer TTP in smokers, particularly among females. Though we do not observe longer TTP among a small sample of smokeless tobacco users compared with never tobacco users, we observe shorter TTP compared with smokers. Further work is needed to more thoroughly delineate the relationship between smokeless tobacco use and TTP and possible mechanisms of tobacco use's effects on reproduction.

Women's Reproductive History Before the Diagnosis of Incident Endometriosis

BACKGROUND

Endometriosis is a gynecologic disease reported to be associated with infertility and, possibly, adverse pregnancy outcomes. While considerable research focuses on pregnancy outcomes following diagnosis and/or treatment, few data actually describe women's reproductive history before diagnosis for a more complete understanding of endometriosis and reproduction.

MATERIALS AND METHODS

The study sample comprised 473 women (aged 18-44 years) undergoing laparoscopies or laparotomies, irrespective of surgical indication at 14 clinical sites, during the period 2007-2009. Upon enrollment and before surgery, women were queried about pregnancy intentions and the time required to become pregnant for planned pregnancies. Endometriosis was defined as surgically visualized disease. Using discrete time survival analysis, we estimated fecundability odds ratios (FORs) and 95% confidence intervals (CIs) to assess time to pregnancy (TTP) after adjusting for potential confounders (age, body composition, cigarette smoking, site). Generalized estimating equations accounted for multiple pregnancy attempts per woman. FORs <1.0 denote a longer TTP or diminished fecundity.

RESULTS

Approximately 66% and 69% of women with and without endometriosis, respectively, reported having a planned pregnancy before surgery, respectively. After adjustment, an endometriosis diagnosis was associated with ≈29% reduction in fecundity or a longer TTP across all pregnancy-trying attempts (adjusted FOR = 0.71; 95% CI 0.46-1.10). While FORs were consistently <1.0, irrespective of endometriosis staging, CIs included 1.

CONCLUSIONS

Women with endometriosis had a longer TTP than unaffected women, irrespective of disease severity, although the findings did not achieve significance. Prior reproductive history may be informative for predicting fecundity and pregnancy outcomes following diagnosis/treatment.

Female digit length ratio (2D:4D) and time-to-pregnancy

STUDY QUESTION

Is the female 2th- to 4th-finger ratio (2D:4D) associated with fecundity as measured by time-to-pregnancy (TTP)?

SUMMARY ANSWER

Our study does not support an association between female 2D:4D and TTP.

WHAT IS KNOWN ALREADY

The 2th- to 4th-finger ratio (2D:4D) has been proposed as a potential indicator of greater androgen exposure during fetal development. Women exposed in utero to unbalanced steroid hormones may have impaired fecundity in the adulthood. Fecundity is often measured by TTP, an epidemiological tool commonly used to assess the impact of environmental factors in human conception.

STUDY DESIGN, SIZE, DURATION

The Maternal-Infant Research on Environmental Chemicals (MIREC) Study is a pregnancy and birth cohort of 2001 women recruited before 14 weeks of gestation in 10 cities across Canada between 2008 and 2011. The present analysis is part of MIREC-CD Plus, a follow-up study in a subsample of some 800 MIREC mothers and their children from 2012 to 2015.

PARTICIPANTS/MATERIALS, SETTING, METHODS

TTP and maternal characteristics were collected from questionnaires administered during the first trimester of pregnancy as part of the MIREC study. Digital pictures of the ventral surface of both hands were obtained in the MIREC mothers at the MIREC-CD Plus follow-up study. The 2D:4D was calculated as the ratio of the second and fourth fingers of each hand. The exposure of interest was the 2D:4D of the women categorized by tertiles, or dichotomized as ≥1 (index finger longer than the ring finger) or <1 (ring finger longer than the index finger, implying greater androgen exposure during fetal development). The final sample included 696 mothers. Statistical analyses included discrete-time Cox proportional hazard models, allowing adjustment for potential confounding factors.

MAIN RESULTS AND THE ROLE OF CHANCE

There was no evidence of diminished/increased fecundability according to the 2D:4D, neither on the right nor on the left hand. In our analysis by tertiles, the smallest 2D:4D (i.e. higher androgen exposure during fetal life) resulted in FORs higher than 1 (i.e. shorter TTP) in both hands, although this was not statistically significant (FOR 1.19 [95% CI 0.93, 1.51] in the right hand and 1.16 [95% CI 0.91, 1.47] in the left hand). In the dichotomous analysis, 2D:4D <1 resulted in FORs higher than 1 (i.e. shorter TTP), but this was also not statistically significant (FOR 1.08 [95% CI 0.88, 1.33] in the right hand and 1.14 [95% CI 0.92, 1.42] in the left hand). Our large sample size resulted in a high statistical power to exclude an association between female 2D:4D and TTP.

LIMITATIONS, REASONS FOR CAUTION

The MIREC Study is a cohort of pregnant women, and therefore, women with infertility were excluded by design from our study.

WIDER IMPLICATIONS OF THE FINDINGS

Our data do not provide evidence for an association between female 2D:4D and fecundity as measured by TTP. Whether the female 2D:4D is a marker of in utero androgen exposure and whether it is associated with fecundity have yet to be determined.

STUDY FUNDING/COMPETING INTEREST

The MIREC Study was funded by Health Canada's Chemicals Management Plan, the Canadian Institute of Health Research (CIHR grant # MOP - 81285), and the Ontario Ministry of the Environment. MIREC-CD Plus was funded by Health Canada's Chemicals Management Plan Research Fund. The 2D:4D component was funded by a research grant from the CIHR-Quebec Training Network in Perinatal Research (QTNPR). M.P. Vélez was supported by a CIHR Fellowship Award, and a QTNPR scholarship. P. Monnier is supported by the Research Institute of the McGill University Health Centre. W.D Fraser is supported by a CIHR Canada Research Chair. There are no conflicts of interest to declare.

Male Reproductive Disorders and Fertility Trends: Influences of Environment and Genetic Susceptibility

It is predicted that Japan and European Union will soon experience appreciable decreases in their populations due to persistently low total fertility rates (TFR) below replacement level (2.1 child per woman). In the United States, where TFR has also declined, there are ethnic differences. Caucasians have rates below replacement, while TFRs among African-Americans and Hispanics are higher. We review possible links between TFR and trends in a range of male reproductive problems, including testicular cancer, disorders of sex development, cryptorchidism, hypospadias, low testosterone levels, poor semen quality, childlessness, changed sex ratio, and increasing demand for assisted reproductive techniques. We present evidence that several adult male reproductive problems arise in utero and are signs of testicular dysgenesis syndrome (TDS). Although TDS might result from genetic mutations, recent evidence suggests that it most often is related to environmental exposures of the fetal testis. However, environmental factors can also affect the adult endocrine system. Based on our review of genetic and environmental factors, we conclude that environmental exposures arising from modern lifestyle, rather than genetics, are the most important factors in the observed trends. These environmental factors might act either directly or via epigenetic mechanisms. In the latter case, the effects of exposures might have an impact for several generations post-exposure. In conclusion, there is an urgent need to prioritize research in reproductive physiology and pathophysiology, particularly in highly industrialized countries facing decreasing populations. We highlight a number of topics that need attention by researchers in human physiology, pathophysiology, environmental health sciences, and demography.

Association of Fecundity With Changes in Adult Female Weight

OBJECTIVE

To evaluate whether weight change since age 18 years, current body mass index (BMI), and BMI at age 18 years are associated with fecundity.

METHODS

Our study included 1,950 women in the Nurses' Health Study 3 (2010-2014), a prospective cohort study, currently attempting pregnancy. Height, current weight, and weight at age 18 years were self-reported on the baseline questionnaire. Every 3-6 months thereafter, women reported the current duration of their pregnancy attempt. Multivariable-accelerated failure time models were used to estimate the time ratios and 95% confidence intervals (CIs).

RESULTS

For every 5-kg increase in body weight from age 18 years, current duration of pregnancy attempt increased by 5% (95% CI 3-7%). Compared with women who maintained weight, the adjusted median current duration was 0.5 months shorter in those who lost weight, 0.3 months longer for those who gained 4-9.9 kg and 10-19.9 kg, and 1.4 months longer for those who gained 20 kg or more (P trend ≤.001). The adjusted time ratio (95% CI) for a 5-kg/m increase in current BMI was 1.08 (1.04-1.12). After multivariable adjustment (including adjustment for current BMI), being underweight at age 18 years (BMI less than 18.5) was associated with a longer current duration of pregnancy attempt compared with normal-weight women (time ratio 1.25, 95% CI 1.07-1.47); however, being overweight or obese at age 18 years was not associated with fecundity.

CONCLUSION

Gaining weight in adulthood, being overweight or obese in adulthood, and being underweight at age 18 years were associated with a modest reduction in fecundity.

LEVEL OF EVIDENCE

II.

Is Anti-Müllerian Hormone Associated With Fecundability? Findings From the EAGeR Trial

OBJECTIVE

The objective of the study was to evaluate whether anti-Müllerian hormone (AMH) is associated with fecundability among women with proven fecundity and a history of pregnancy loss.

DESIGN

This was a prospective cohort study within a multicenter, block-randomized, double-blind, placebo-controlled clinical trial ( clinicaltrials.gov , number NCT00467363).

SETTING

The study was conducted at four US medical centers (2006-2012).

PARTICIPANTS

Participating women were aged 18-40 years, with a history of one to two pregnancy losses who were actively attempting pregnancy.

MAIN OUTCOME MEASURES

Time to human chorionic gonadotropin detected and clinical pregnancy were assessed using Cox proportional hazard regression models to estimate fecundability odds ratios (fecundability odds ratios with 95% confidence interval [CI]) adjusted for age, race, body mass index, income, low-dose aspirin treatment, parity, number of previous losses, and time since most recent loss. Analyses examined by preconception AMH levels: low (<1.00 ng/mL, n = 124); normal (referent 1.00-3.5 ng/mL, n = 595); and high (>3.5 ng/mL, n = 483).

RESULTS

Of the 1202 women with baseline AMH levels, 82 women with low AMH (66.1%) achieved an human chorionic gonadotropin detected pregnancy, compared with 383 with normal AMH (65.2%) and 315 with high AMH level (65.2%). Low or high AMH levels relative to normal AMH (referent) were not associated with fecundability (low AMH: fecundability odds ratios 1.13, 95% CI 0.85-1.49; high AMH: FOR 1.04, 95% CI 0.87-1.24).

CONCLUSIONS

Lower and higher AMH values were not associated with fecundability in unassisted conceptions in a cohort of fecund women with a history of one or two prior losses. Our data do not support routine AMH testing for preconception counseling in young, fecund women.

Maternal Recall Error in Retrospectively Reported Time-to-Pregnancy: an Assessment and Bias Analysis

BACKGROUND

Epidemiologic studies of fecundability often use retrospectively measured time-to-pregnancy (TTP), thereby introducing potential for recall error. Little is known about how recall error affects the bias and precision of the fecundability odds ratio (FOR) in such studies.

METHODS

Using data from the Danish Snart-Gravid Study (2007-12), we quantified error for TTP recalled in the first trimester of pregnancy relative to prospectively measured TTP among 421 women who enrolled at the start of their pregnancy attempt and became pregnant within 12 months. We defined recall error as retrospectively measured TTP minus prospectively measured TTP. Using linear regression, we assessed mean differences in recall error by maternal characteristics. We evaluated the resulting bias in the FOR and 95% confidence interval (CI) using simulation analyses that compared corrected and uncorrected retrospectively measured TTP values.

RESULTS

Recall error (mean = -0.11 months, 95% CI -0.25, 0.04) was not appreciably associated with maternal age, gravidity, or recent oral contraceptive use. Women with TTP > 2 months were more likely to underestimate their TTP than women with TTP ≤ 2 months (unadjusted mean difference in error: -0.40 months, 95% CI -0.71, -0.09). FORs of recent oral contraceptive use calculated from prospectively measured, retrospectively measured, and corrected TTPs were 0.82 (95% CI 0.67, 0.99), 0.74 (95% CI 0.61, 0.90), and 0.77 (95% CI 0.62, 0.96), respectively.

CONCLUSIONS

Recall error was small on average among pregnancy planners who became pregnant within 12 months. Recall error biased the FOR of recent oral contraceptive use away from the null by 10%. Quantitative bias analysis of the FOR can help researchers quantify the bias from recall error.

Work schedule and physical factors in relation to fecundity in nurses

OBJECTIVES

To evaluate the association of work schedule and physical factors with fecundity.

METHODS

Women currently employed outside the home and trying to get pregnant (n=1739) in the Nurses' Health Study 3 cohort (2010-2014) were included in this analysis. Work schedule and physical labour were self-reported on the baseline questionnaire, and every 6 months thereafter the women reported the duration of their ongoing pregnancy attempt. Multivariable accelerated failure time models were used to estimate time ratios (TR) and 95% CIs.

RESULTS

Among the 1739 women (median age=33 years, 93% Caucasian) the estimated proportions of women not pregnant after 12 and 24 months were 16% and 5%, respectively. None of the various shift work patterns were associated with duration of pregnancy attempt (as a surrogate for fecundity). However, women working >40 h/week had a 20% (95% CI 7 to 35%) longer median duration of pregnancy attempt compared to women working 21-40 h/week (p-trend=0.005). Women whose work entailed heavy lifting or moving (ie, 25+ pounds) >15 times/day also had a longer median duration of pregnancy attempt (adjusted TR=1.49; 95% CI 1.20 to 1.85) compared to women who never lifted or moved heavy loads (p-trend=0.002). The association between heavy moving and lifting and duration of pregnancy attempt was more pronounced among overweight or obese women (body mass index, BMI<25: TR=1.17; 95% CI 0.88 to 1.56; BMI≥25: TR=2.03, 95% CI 1.48 to 2.79; p-interaction=0.007).

CONCLUSIONS

Working greater than 40 h per week and greater frequency of lifting or moving a heavy load were associated with reduced fecundity in a cohort of nurses planning pregnancy.

Development and initial validation of a fertility experiences questionnaire

Background

Many women throughout the world have history of subfertility (resolved or unresolved), but much remains unknown about services and treatments chosen.

Methods

We developed a mixed-mode fertility experiences questionnaire (FEQ) in 2009 through literature review and iterative pilot work to optimize question format and mode of administration. The focus of the FEQ is to collect data retrospectively on time at risk for pregnancy, fertility treatments received and declined, pregnancy, time to pregnancy and pregnancy outcomes. We conducted a validation of key elements of the FEQ with comparison to medical records in 2009 and 2010. The validation sample was selected from women initially seen at a specialized fertility treatment center in Utah in 2004.

Results

The FEQ was optimized with two components: 1) written (paper or web-based), self-administered, followed by 2) telephone- administered questions. In 63 patients analyzed, high levels of correlation were identified between patient self-report and medical records for the use of intrauterine insemination and assisted reproductive technology, pregnancy and live birth histories, time at risk for pregnancy and time to pregnancy. There was low correlation between medical records and self-report for the use of oral ovulation drugs and injectable ovulation drugs. Compared to the medical record, the FEQ was over 90 % sensitive for all elements, except injectable ovulation drugs (70 % sensitivity).

Conclusions

The FEQ accurately captured elements of fertility treatment history at 5–6 years after the first visit to a specialty clinic.

Electronic supplementary material

The online version of this article (doi:10.1186/s12978-015-0054-3) contains supplementary material, which is available to authorized users.

Clustering of retrospectively reported and prospectively observed time-to-pregnancy

PURPOSE

Given reportedly high clustering but limited validity of retrospectively reported time-to-pregnancy (TTP), we assessed within-woman clustering for retrospectively reported TTPs alone and including gold-standard prospectively observed TTPs among women with 2 or more retrospectively reported and 1 or more prospectively observed TTPs. We further investigated whether past trying times inform future trying time among women with 1 or more retrospectively reported and 1 or more prospectively observed TTPs.

METHODS

Five hundred one couples attempting pregnancy were prospectively observed until human chorionic gonadotropin pregnancy or 12 months of trying. Women reported TTP for past planned pregnancies. Clustering as measured by the frailty variance was estimated using discrete Cox frailty models, adjusted for age, body mass index, smoking at each attempt. Utility of past attempts to inform future attempts was assessed with discrete Cox models and relative risk regression, adjusted for enrollment age, body mass index, smoking.

RESULTS

Seventy-five women with 2 or more prior pregnancies contributed 180 retrospective and 91 prospective TTPs for frailty modeling. Retrospectively reported TTP clustering was high (frailty variance = 0.89) but substantially lower when including prospectively observed TTPs (frailty variance = 0.42). Among 202 women with 1 or more prior pregnancies, past trying times did not inform future trying time.

CONCLUSIONS

TTP recall rather than TTP may account for clustering. Past trying times may not inform future trying times.