Vitamin D and Reproductive Hormones Across the Menstrual Cycle.

STUDY QUESTION: How do the calciotropic hormones (25-hydroxyvitamin D, 1,25-dihydroxyvitamin D and intact parathyroid hormone (iPTH)) vary across the menstrual cycle and do cyclic patterns of reproductive hormones (estradiol, progesterone, LH, FSH) differ by vitamin D status? SUMMARY ANSWER: Calciotropic hormones vary minimally across the menstrual cycle; however, women with 25-hydroxyvitamin D below 30 ng/ml have lower mean estradiol across the menstrual cycle. WHAT IS KNOWN ALREADY: Prior human studies suggest that vitamin D status is associated with fecundability, but the mechanism is unknown. Exogenous estrogens and prolonged changes in endogenous estradiol (pregnancy or menopause) influence concentrations of 25-hydroxyvitamin D. In vitro, treatment with 1,25-dihydroxyvitamin D increases steroidogenesis in ovarian granulosa cells. There are little data about changes in calciotropic hormones across the menstrual cycle or cyclic patterns of reproductive hormones by categories of vitamin D status. STUDY DESIGN, SIZE, DURATION: A prospective cohort study of 89 self-identified white women aged 18-44, across two menstrual cycles. Participants were a subset of the BioCycle Study, a community-based study conducted at the University of Buffalo, 2005-2007. PARTICIPANTS/MATERIALS, SETTING, METHODS: Eligible participants had self-reported regular menstrual cycles between 21 and 35 days and were not using hormonal contraception or vitamins. Early morning fasting blood samples were drawn at up to eight study visits per cycle. Visits were timed to capture information in all cycle phases. Serum samples for 89 women (N = 163 menstrual cycles) were analyzed for estradiol, progesterone, LH, FSH and 25-hydroxyvitamin D (25(OH)D). Variability in calciotropic hormones within and across menstrual cycles was assessed using intraclass correlation coefficients and non-linear mixed models. Given the relative stability of the calciotropic hormones across the menstrual cycle, non-linear mixed models were used to examine differences in the cyclic patterns of estradiol, progesterone, LH and FSH by categories of each calciotropic hormone (split at the median). These models were conducted for all ovulatory cycles (N = 142 ovulatory menstrual cycles) and were adjusted for age, BMI (measured in clinic) and self-reported physical activity. MAIN RESULTS AND THE ROLE OF CHANCE: Median 25(OH)D concentration was 29.5 ng/ml (SD 8.4), and only 6% of women had vitamin D deficiency (<20 ng/ml). The mean concentration of 25(OH)D did not differ between the luteal and follicular phase; however, both 1,25(OH)2D and iPTH showed small fluctuations across the menstrual cycle with the highest 1,25(OH)2D (and lowest iPTH) in the luteal phase. Compared with women who had mean 25(OH)D ≥30 ng/ml, women with lower 25(OH)D had 13.8% lower mean estradiol (95% confidence interval: -22.0, -4.7) and 10.8% lower free estradiol (95% CI: -0.07, -0.004). Additionally, compared to women with iPTH ≤36 pg/ml, women with higher concentrations of iPTH had 12.7% lower mean estradiol (95% CI: -18.7, -6.3) and 7.3% lower progesterone (95% CI: -13.3, -0.9). No differences in the cyclic pattern of any of the reproductive hormones were observed comparing cycles with higher and lower 1,25(OH)2D. LIMITATIONS, REASONS FOR CAUTION: Women included in this study had self-reported 'regular' menstrual cycles and very few were found to have 25(OH)D deficiency. This limits our ability to examine cycle characteristics, anovulation and the effects of concentrations of the calciotropic hormones found in deficient individuals. Additionally, the results may not be generalizable to women with irregular cycles, other races, or populations with a higher prevalence of vitamin D deficiency. WIDER IMPLICATIONS OF THE FINDINGS: These findings support current clinical practice that does not time testing for vitamin D deficiency to the menstrual cycle phase. We find that women with lower vitamin D status (lower 25(OH)D or higher iPTH) have lower mean concentrations of estradiol across the menstrual cycle. Although this study cannot identify a mechanism of action, further in vitro work or clinical trials may help elucidate the biologic mechanisms linking calciotropic and reproductive hormones. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the Intramural Research Programs of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health (contract numbers: HHSN275200403394C, HHSN275201100002I and Task 1 HHSN27500001) and the National Institute of Environmental Health Sciences. There are no competing interests.

Pre-conception 25-hydroxyvitamin D (25(OH)D) and fecundability.

STUDY QUESTION: Is pre-conception 25(OH)D associated with the per cycle probability of conception, i.e fecundability, in a prospective cohort study? SUMMARY ANSWER: There are suggestive associations of high 25(OH)D (at least 50 ng/ml) with increased fecundability and low 25(OH)D (<20 ng/ml) with reduced fecundability, but the estimates were imprecise. WHAT IS KNOWN ALREADY: Vitamin D has been associated with reproductive function and fertility in animal studies, but few human studies exist. STUDY DESIGN, SIZE, DURATION: This community-based prospective cohort study included 522 women attempting to become pregnant between 2010 and 2016. The women completed online daily and monthly diaries until a positive home pregnancy test was observed or 12 months had elapsed. PARTICIPANTS/MATERIALS, SETTING, METHODS: The study included women from central North Carolina who were aged 30-44 with no history of infertility, with no more than 3 months of attempt time at recruitment. Women recorded vaginal bleeding so that the ongoing number of attempt cycles could be counted and used to quantify a woman's pregnancy attempt time. Blood collected at the study entry was analysed for 25(OH)D using liquid chromatography tandem mass spectrometry. Associations with fecundability were estimated with a log-binomial discrete time-to-event model. MAIN RESULTS AND THE ROLE OF CHANCE: Among 522 women, 257 conceived during the study. The mean age was 33 years and the mean 25(OH)D was 36 ng/ml. There was an estimated 10% higher fecundability with each 10 ng/ml increase in 25(OH)D (fecundability ratio (FR) 1.10, 95% CI: 0.96, 1.25). The suggestive dose-response association with the continuous measure of 25(OH)D was driven by women in the lowest and the highest categories of 25(OH)D. Compared to women with 25(OH)D of 30-40 ng/ml, women below 20 ng/ml had an estimated 45% reduction in fecundability (FR (CI): 0.55 (0.23, 1.32)), and women with at least 50 ng/ml had an estimated 35% increase in fecundability (FR (CI): 1.35 (0.95, 1.91)). Across these three categories (25(OH)D of <20 ng/ml, 30-40 ng/ml and > 50 ng/ml), the probability of taking longer than 6 months to conceive was, respectively, 51% (17%, 74%), 28% (17%, 39%) and 15% (10%, 37%). LIMITATIONS, REASONS FOR CAUTION: While the distribution of 25(OH)D was wide, the number of observed cycles with high 25(OH)D (N = 107) or low 25(OH)D (N = 56) was small. WIDER IMPLICATIONS OF THE FINDINGS: Our findings are consistent with prior reports of reduced fertility in women with 25(OH)D concentrations below the clinically defined deficiency level (20 ng/ml). Further studies are needed to evaluate the possible reproductive benefits of considerably higher 25(OH)D concentration (>50 ng/ml). STUDY FUNDING/COMPETING INTEREST(S): This research was supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development of the National Institutes of Health (NIH) under award numbers R00HD079659 and R01HD067683 and supported in part by the Intramural Research Program of the National Institute of Environmental Health Sciences, under projects ES103086, ES049003 and ES044003. ClearBlue ovulation predictor kits were generously donated to AMZJ and AJW by Swiss Precision Diagnostics. Drs Wilcox and Jukic report non-financial support from Swiss Precision Diagnostics during the conduct of the study; Dr Jukic reports non-financial support from Theralogix, LLC, outside the submitted work. Otherwise there are no competing interests. TRIAL REGISTRATION NUMBER: N/A.

A single baseline ultrasound assessment of fibroid presence and size is strongly predictive of future uterine procedure: 8-year follow-up of randomly sampled premenopausal women aged 35-49 years.

STUDY QUESTION: How well can a single baseline ultrasound assessment of fibroid burden (presence or absence of fibroids and size of largest, if present) predict future probability of having a major uterine procedure? SUMMARY ANSWER: During an 8-year follow-up period, the risk of having a major uterine procedure was 2% for those without fibroids and increased with fibroid size for those with fibroids, reaching 47% for those with fibroids ≥ 4 cm in diameter at baseline. WHAT IS KNOWN ALREADY: Uterine fibroids are a leading indication for hysterectomy. However, when fibroids are found, there are few available data to help clinicians advise patients about disease progression. STUDY DESIGN, SIZE, DURATION: Women who were 35-49 years old were randomly selected from the membership of a large urban health plan; 80% of those determined to be eligible were enrolled and screened with ultrasound for fibroids ≥ 0.5 cm in diameter. African-American and white premenopausal participants who responded to at least one follow-up interview (N = 964, 85% of those eligible) constituted the study cohort. During follow-up (5822 person-years), participants self-reported any major uterine procedure (67% hysterectomies). Life-table analyses and Cox regression (with censoring for menopause) were used to estimate the risk of having a uterine procedure for women with no fibroids, small (<2 cm in diameter), medium (2-3.9 cm), and large fibroids (≥ 4 cm). Differences between African-American and white women, importance of a clinical diagnosis of fibroids prior to study enrollment, and the impact of submucosal fibroids on risk were investigated. PARTICIPANTS/MATERIALS, SETTING, METHODS: There was a greater loss to follow-up for African-Americans than whites (19 versus 11%). For those with follow-up data, 64% had fibroids at baseline, 33% of whom had had a prior diagnosis. Of those with fibroids, 27% had small fibroids (<2 cm in diameter), 46% had medium (largest fibroid 2-3.9 cm in diameter), and 27% had large fibroids (largest ≥ 4 cm in diameter). Twenty-one percent had at least one submucosal fibroid. MAIN RESULTS AND THE ROLE OF CHANCE: Major uterine procedures were reported by 115 women during follow-up. The estimated risk of having a procedure in any given year of follow-up for those with fibroids compared with those without fibroids increased markedly with fibroid-size category (from 4-fold, confidence interval (CI) (1.4-11.1) for the small fibroids to 10-fold, CI (4.4-24.8) for the medium fibroids, to 27-fold, CI (11.5-65.2) for the large fibroids). This influence of fibroid size on risk did not differ between African-Americans and whites (P-value for interaction = 0.88). Once fibroid size at enrollment was accounted for, having a prior diagnosis at the time of ultrasound screening was not predictive of having a procedure. Exclusion of women with a submucosal fibroid had little influence on the results. The 8-year risk of a procedure based on lifetable analyses was 2% for women with no fibroids, 8, 23, and 47%, respectively, for women who had small, medium or large fibroids at enrollment. Given the strong association of fibroid size with subsequent risk of a procedure, these findings are unlikely to be due to chance. LIMITATIONS, REASONS FOR CAUTION: Despite a large sample size, the number of women having procedures during follow-up was relatively small. Thus, covariates such as BMI, which were not important in our analyses, may have associations that were too small to detect with our sample size. Another limitation is that the medical procedures were self-reported. However, we attempted to retrieve medical records when participants agreed, and 77% of the total procedures reported were verified. Our findings are likely to be generalizable to other African-American and white premenopausal women in their late 30s and 40s, but other ethnic groups have not been studied. WIDER IMPLICATIONS OF THE FINDINGS: Though further studies are needed to confirm and extend the results, our findings provide an initial estimate of disease progression that will be helpful to clinicians and their patients.

Use of depot medroxyprogesterone acetate and prevalent leiomyoma in young African American women.

STUDY QUESTION: Is use of depot medroxyprogesterone acetate (DMPA) a risk factor for or a protective factor against prevalent uterine leiomyoma? SUMMARY ANSWER: Ever use of DMPA was associated with a decreased risk (adjusted risk ratio (RR): 0.8, 95% confidence interval (CI): 0.6, 0.9) of prevalent leiomyoma in young African American women. WHAT IS KNOWN ALREADY: Although progesterone is associated with growth of leiomyoma, previous epidemiological studies have shown a protective association for DMPA use. These previous studies may have been biased by studying clinically diagnosed leiomyoma (DMPA may mask symptoms thus delaying diagnoses). STUDY DESIGN, SIZE, DURATION: Cross sectional analysis of baseline data from a cohort study of 1696 African American women. PARTICIPANTS/MATERIALS, SETTING, METHODS: Community-based recruitment (e.g. letters, flyers, radio and TV announcements) were used to enroll African American women between 23 and 34 years old without a previous diagnosis of leiomyoma in the Metropolitan Detroit area. Extensive questionnaire data were used to determine DMPA use and screening ultrasound detected the presence of leiomyoma ≥0.5 cm in diameter. Relative risks with adjustment for covariates were calculated for the presence of leiomyoma based on ever use of DMPA as well as duration and recency of use. MAIN RESULTS AND THE ROLE OF CHANCE: Among the 1696 volunteers who enrolled, 43% had used DMPA. Leiomyoma were detected in 17% of those who had ever used DMPA compared with 26% of those who had never used DMPA. The reduction in prevalence remained after adjustment for potential confounders and was highest among women who had used DMPA for more than 4 years (adjusted RR: 0.5, 95% CI: 0.3, 0.8). The reduction in risk was seen for women whose most recent use was up to 8 years prior to study enrollment. LIMITATIONS, REASONS FOR CAUTION: The use of cross-sectional data means that the timing of initial fibroid development is not known, so the temporality of the association is uncertain. However in this sample of young women, most fibroids were small, suggesting that DMPA exposure may have occurred before leiomyoma development. WIDER IMPLICATIONS OF THE FINDINGS: Our findings are in agreement with previous epidemiological studies, but protected from the bias inherent in the use of clinically diagnosed leiomyoma. Although further studies will be needed to elucidate the mechanism, use of DMPA as a contraceptive appears to provide long lasting protection against uterine leiomyoma. STUDY FUNDING/COMPETING INTERESTS: No competing interests. This research was supported in part by the Intramural Research Program of the NIH, National Institute of Environmental Health Sciences, and in part by funds allocated for health research by the American Recovery and Reinvestment Act. TRIAL REGISTRATION NUMBER: N/A.

Tubal ligation in relation to menopausal symptoms and breast cancer risk.

BACKGROUND: Local inflammation after tubal ligation may affect ovarian function and breast cancer risk. METHODS: We analysed tubal ligation, menopausal characteristics, and breast cancer risk in the Sister Study cohort (N=50,884 women). RESULTS: Tubal ligation was associated with hot flashes (hazard ratio (HR) 1.09; 95% confidence interval (CI): 1.06-1.12) but not menopausal age (HR 0.99; 95% CI: 0.96-1.02). Tubal ligation did not have an impact on breast cancer overall (HR 0.95; 95% CI: 0.85-1.06), but had a suggested inverse relation with oestrogen receptor+/progesterone receptor+ invasive tumours (HR 0.84; 95% CI: 0.70-1.01), possibly because of subsequent hysterectomy/bilateral oophorectomy. CONCLUSION: Tubal ligation does not influence overall breast cancer risk.

Length of human pregnancy and contributors to its natural variation.

STUDY QUESTION: How variable is the length of human pregnancy, and are early hormonal events related to gestational length? SUMMARY ANSWER: Among natural conceptions where the date of conception (ovulation) is known, the variation in pregnancy length spanned 37 days, even after excluding women with complications or preterm births. WHAT IS KNOWN ALREADY: Previous studies of length of gestation have either estimated gestational age by last menstrual period (LMP) or ultrasound (both imperfect measures) or included pregnancies conceived through assisted reproductive technology. STUDY DESIGN, SIZE, DURATION: The Early Pregnancy Study was a prospective cohort study (1982-85) that followed 130 singleton pregnancies from unassisted conception to birth, with detailed hormonal measurements through the conception cycle; 125 of these pregnancies were included in this analysis. PARTICIPANTS/MATERIALS, SETTING, METHODS: We calculated the length of gestation beginning at conception (ovulation) in 125 naturally conceived, singleton live births. Ovulation, implantation and corpus luteum (CL) rescue pattern were identified with urinary hormone measurements. We accounted for events that artificially shorten the natural length of gestation (Cesarean delivery or labor induction, i.e. 'censoring') using Kaplan-Meier curves and proportional hazards models. We examined hormonal and other factors in relation to length of gestation. We did not have ultrasound information to compare with our gold standard measure. MAIN RESULTS AND THE ROLE OF CHANCE: The median time from ovulation to birth was 268 days (38 weeks, 2 days). Even after excluding six preterm births, the gestational length range was 37 days. The coefficient of variation was higher when measured by LMP (4.9%) than by ovulation (3.7%), reflecting the variability of time of ovulation. Conceptions that took longer to implant also took longer from implantation to delivery (P = 0.02). CL rescue pattern (reflecting ovarian response to implantation) was predictive (P = 0.006): pregnancies with a rapid progesterone rise were longer than those with delayed rise (a 12-day difference in the median gestational length). Mothers with longer gestations were older (P = 0.02), had longer pregnancies in other births (P < 0.0001) and were heavier at birth (P = 0.01). We did not see an association between the length of gestation and several factors that have been associated with gestational length in previous studies: body mass index, alcohol intake, parity or offspring sex. LIMITATIONS, REASONS FOR CAUTION: The sample size was small and some exposures were rare, reducing power to detect weak associations. WIDER IMPLICATIONS OF THE FINDINGS: Human gestational length varies considerably even when measured exactly (from ovulation). An individual woman's deliveries tend to occur at similar gestational ages. Events in the first 2 weeks after conception are predictive of subsequent pregnancy length, and may suggest pathways underlying the timing of delivery. STUDY FUNDING/COMPETING INTEREST: This research was supported by the Intramural Research Program of the NIH, National Institute of Environmental Health Sciences. None of the authors has any conflict of interest to declare.

First-trimester bleeding characteristics associate with increased risk of preterm birth: data from a prospective pregnancy cohort.

BACKGROUND: Prior evidence linking first-trimester bleeding with preterm birth (PTB, <37 weeks gestation) risk has been inconsistent and may be biased by subject selection and/or incomplete documentation of bleeding episodes for all participants. Prior studies have not carefully examined the role of bleeding characteristics in PTB risk. In the present study, we estimate the association between first-trimester bleeding and PTB in a non-clinical prospective cohort and test whether bleeding characteristics better predict risk. METHODS: Women were enrolled in Right from the Start (2000-2009), a prospective pregnancy cohort. Data about bleeding and bleeding characteristics were examined with logistic regression to assess association with PTB. RESULTS: Among 3978 pregnancies 344 were PTB and 3634 term. Bleeding was reported by 986 (26%) participants. After screening candidate confounders, only multiple gestations remained in the model. Bleeding associated with PTB [odds ratio (OR)(adjusted) = 1.40, 95% confidence interval (CI) 1.09-1.80]. Risk did not vary by race/ethnicity. Compared with non-bleeders, PTB risk was higher for bleeding with red color (OR(adjusted) = 1.92, 95% CI, 1.32-2.82), for heavy episodes (OR(adjusted) = 2.40, 95% CI 1.18-4.88) and long duration (OR(adjusted) = 1.67, 95% CI 1.17-2.38). CONCLUSIONS: Bleeding associated with PTB was not confounded by common risk factors for bleeding or PTB. PTB risk was greatest for women with heavy bleeding episodes with long duration and red color and would suggest that combining women with different bleeding characteristics may affect the accuracy of risk assessment. These data suggest a candidate etiologic pathway for PTB and warrant further investigation of the biologic mechanisms.

The association of maternal factors with delayed implantation and the initial rise of urinary human chorionic gonadotrophin.

BACKGROUND Late implantation and the pattern of early rise in hCG have been associated with early pregnancy loss. We explored factors that might be predictive of these markers of poor embryonic health in spontaneously conceived pregnancies. METHODS Participants in the North Carolina Early Pregnancy Study collected daily first-morning urine specimens while attempting to conceive. Samples were assayed for estrogen and progesterone metabolites (to identify day of ovulation) and hCG (to detect conception). Data were available for 190 pregnancies, 48 of which ended in early loss (within 6 weeks of the last menstrual period). We used logistic regression to identify characteristics associated with late implantation (≥10 days post-ovulation). For pregnancies surviving at least 6 weeks (n= 142), we used linear mixed models to identify factors associated with variations in hCG rise in the first 7 days from detection. RESULTS Later implantation was associated with current maternal smoking [odds ratio (OR): 5.7; 95% confidence interval (CI): 1.1-30] and with oocytes that were likely to have been fertilized late in their post-ovulatory lifespan (OR: 5.1; CI: 1.9-16). Older women had a faster rise in hCG (P= 0.01), as did women who had relatively late menarche (P for trend = 0.02). Women exposed in utero to diethylstilbestrol showed an unusual pattern of slow initial hCG rise followed by a fast increase, a pattern significantly different from that of unexposed women (P= 0.002). CONCLUSIONS Although limited by small numbers and infrequent exposures, our analyses suggest that a woman's exposures both early in life and at the time of pregnancy may influence early development of the conceptus.

In utero exposure to maternal smoking and women's risk of fetal loss in the Norwegian Mother and Child Cohort (MoBa).

BACKGROUND: Whether in utero exposure to tobacco smoke increases a woman's risk of fetal loss later in life is unknown, though data on childhood exposure suggest an association may exist. This study evaluated the association between in utero exposure to tobacco smoke and fetal loss in the Norwegian Mother and Child Cohort Study (MoBa), which enrolled ∼40% of the pregnant women in Norway from 1999 to 2008. METHODS: Information on exposure to tobacco smoke in utero, the woman's own smoking behavior during pregnancy and other factors was obtained by a questionnaire completed at ∼17 weeks of gestation. Subsequent late miscarriage (fetal death <20 weeks) and stillbirth (fetal death ≥ 20 weeks) were ascertained from the Norwegian Medical Birth Registry. This analysis included 76 357 pregnancies (MoBa data set version 4.301) delivered by the end of 2008; 59 late miscarriages and 270 stillbirths occurred. Cox proportional hazards models were fit for each outcome and for all fetal deaths combined. RESULTS: The adjusted hazard ratio (HR) of late miscarriage was 1.23 [95% confidence interval (CI), 0.72-2.12] in women with exposure to maternal tobacco smoke in utero when compared with non-exposed women. The corresponding adjusted HR for stillbirths was 1.11 (95% CI, 0.85-1.44) and for all fetal deaths combined, it was 1.12 (95% CI, 0.89-1.43). CONCLUSIONS: The relatively wide CI around the HR for miscarriage reflected the limited power to detect an association, due to enrollment around 17 weeks of gestation. However, for in utero exposure to tobacco smoke and risk of stillbirth later in life, where the study power was adequate, our data provided little support for an association.

Fecundability among women with type 1 and type 2 diabetes in the Norwegian Mother and Child Cohort Study.

AIMS/HYPOTHESIS: We assessed the effects of type 1 diabetes and type 2 diabetes on fecundability (as manifest by increased time-to-pregnancy [TTP]) in a large cohort of pregnant women. METHODS: This study is based on the Norwegian Mother and Child Cohort Study. Members of this large cohort were enrolled early in pregnancy and asked about TTP and other factors. Among the 58,004 women included in the analysis, we identified 221 cases of type 1 diabetes and 88 cases of type 2 diabetes using the Medical Birth Registry of Norway. A logistic analogue of the proportional probability model, a Cox-like discrete-time model, was used to compute fecundability odds ratios (FORs) and 95% CI for type 1 diabetes and type 2 diabetes, adjusted for maternal age and prepregnancy BMI. RESULTS: Compared with non-diabetic women, the adjusted FOR for women with type 1 diabetes was 0.76 (95% CI 0.64-0.89) and the adjusted FOR for women with type 2 diabetes was 0.64 (95% CI 0.48-0.84). These FORs did not change substantively and remained statistically significant after excluding women with irregular menstrual cycles and accounting for cycle length. CONCLUSIONS/INTERPRETATION: The results from the present study provide evidence of substantially decreased fecundability for women with type 1 and type 2 diabetes, even among those with a normal menstrual cycle.

Urinary hCG patterns during the week following implantation.

BACKGROUND: Human chorionic gonadotrophin (hCG) is used to monitor pregnancy status. Yet the pattern of hCG excretion in the first week following implantation has not been adequately described. Therefore the aim of this study was to describe the average profile of hCG and its variability during the 7 days following estimated implantation in a population of naturally conceived pregnancies. METHODS: We measured daily hCG concentrations in first-morning urine for 142 clinical pregnancies from women with no known fertility problems. Mixed-effects regression models were used to estimate the hCG trajectory and its variability in relation to pregnancy outcomes. RESULTS: hCG rose 3-fold between the day of detection and the next day (95% CI = 2.7-3.4). The relative rate of rise decreased thereafter, reaching 1.6-fold (95% CI = 1.5-1.8) between days 6 and 7. HCG levels followed a log-quadratic trajectory, and the patterns of rise were unrelated to number of fetuses, risk of spontaneous abortion or sex of the baby. Later implantations (after 10 luteal days) produced slower rates of increase. CONCLUSIONS: Although mean hCG follows a log-quadratic trajectory during the first week of detectability, there is high variability across pregnancies. Later implantation may reflect characteristics of the uterus or conceptus that slow hCG production.

Bleeding following pregnancy loss before 6 weeks' gestation.

BACKGROUND: Pregnancy loss before 6 weeks' gestation is common, but little has been reported about the associated bleeding. We compared women's bleeding following a pregnancy loss before 6 weeks' gestation with their typical menstruation. METHODS: Women provided daily urine samples while trying to become pregnant and recorded the number of pads and tampons used each day. Thirty-six women had complete bleed data for a loss before 6 weeks' gestation and one or more non-pregnant cycles. RESULTS: Mean bleed length following a pregnancy loss was 0.4 days longer than the woman's average menstrual bleed (P = 0.01), primarily because of more days of light bleeding. Although there was no overall increase in the total number of pads plus tampons used, women with losses bled less than their typical menses following pregnancies of very short duration and more than usual for the pregnancies lasting the longest. CONCLUSIONS: Overall, the bleeding associated with pregnancy loss before 6 weeks' gestation is similar to menstrual bleeding and unlikely to be recognized as pregnancy loss. The intriguing finding that pregnancies of very short duration were associated with less bleeding than the woman's typical menses might reflect endometrial factors associated with loss.

Fertility and exposure to solvents among families in the Agricultural Health Study.

BACKGROUND: Several studies have reported associations between solvent exposure and reduced female fertility, but the evidence is inconclusive for male fertility. OBJECTIVES: To investigate the impact of solvent exposure on subfertility among families of male licensed pesticide applicators in the Agricultural Health Study cohort. METHODS: The couples enrolled between 1993 and 1997. Cross-sectional questionnaire information on work tasks was used to assess exposure to solvents. The data were limited to couples (wife aged less than 40 years) with an attempt at pregnancy in the last four years (n = 2112). RESULTS: Twenty eight per cent of the couples were defined as subfertile (not conceiving a pregnancy after at least 12 months of unprotected intercourse, regardless of whether or not a pregnancy ultimately occurred). Adjusted subfertility odds ratios (OR) for exposure to solvents were calculated with logistic regression. Female (OR 1.42, 95% CI 1.15 to 1.75) and male exposure to solvents (OR 1.21 (95% CI 0.93 to 1.57) for monthly exposure and 1.40 (95% CI 0.97 to 2.03) for daily or weekly exposure) were associated with subfertility. In farming, spouses may share or exchange jobs. To account for potential dual exposure, variables for parental exposure (either parent exposed or both parents exposed) were also defined. Both were strongly associated with subfertility (OR 1.62 (95% CI 1.20 to 2.17) and OR 2.10 (95% CI 1.22 to 3.60), respectively). CONCLUSIONS: Solvents may impair fertility of either gender, though the evidence for female effects is stronger than for male effects.

Biomarkers of oxidative stress study II: are oxidation products of lipids, proteins, and DNA markers of CCl4 poisoning?

Oxidation products of lipids, proteins, and DNA in the blood, plasma, and urine of rats were measured as part of a comprehensive, multilaboratory validation study searching for noninvasive biomarkers of oxidative stress. This article is the second report of the nationwide Biomarkers of Oxidative Stress Study using acute CCl4 poisoning as a rodent model for oxidative stress. The time-dependent (2, 7, and 16 h) and dose-dependent (120 and 1200 mg/kg i.p.) effects of CCl4 on concentrations of lipid hydroperoxides, TBARS, malondialdehyde (MDA), isoprostanes, protein carbonyls, methionine sulfoxidation, tyrosine products, 8-hydroxy-2'-deoxyguanosine (8-OHdG), leukocyte DNA-MDA adducts, and DNA-strand breaks were investigated to determine whether the oxidative effects of CCl4 would result in increased generation of these oxidation products. Plasma concentrations of MDA and isoprostanes (both measured by GC-MS) and urinary concentrations of isoprostanes (measured with an immunoassay or LC/MS/MS) were increased in both low-dose and high-dose CCl4-treated rats at more than one time point. The other urinary markers (MDA and 8-OHdG) showed significant elevations with treatment under three of the four conditions tested. It is concluded that measurements of MDA and isoprostanes in plasma and urine as well as 8-OHdG in urine are potential candidates for general biomarkers of oxidative stress. All other products were not changed by CCl4 or showed fewer significant effects.

Biomarkers of oxidative stress study III. Effects of the nonsteroidal anti-inflammatory agents indomethacin and meclofenamic acid on measurements of oxidative products of lipids in CCl4 poisoning.

Plasma and urinary levels of malondialdehyde-like products (MDA) and isoprostanes were identified as markers of in vivo lipid peroxidation in an animal model of CCl4 poisoning. We sought to determine the extent to which the formation of these oxidation products is influenced by inhibition of the cyclooxygenase enzymes which catalytically generate proinflammatory lipid peroxidation products known as prostaglandins and thromboxane. In the present studies, after induction of oxidant stress in rats with CCl4, lipid peroxidation products measured in plasma and urine demonstrate that isoprostanes and MDA can be partially inhibited by cyclooxygenase inhibitors, albeit to different extents. The lowering of isoprostane and MDA formation, however, may not to due primarily to the diminution of catalytic generation of isoprostanes or MDA by the cyclooxygenases but, rather, may be the result of the suppression of nonenzymatic lipid peroxidation. This is suggested since 8,12-iso-iPF2alpha-VI is also reduced by indomethacin, yet, unlike other isoprostanes and MDA, it is not generated catalytically by the cyclooxygenase. Thus, although the two cyclooxygenase inhibitors we tested have statistically significant effects on the measurements of both isoprostanes and MDA in this study, the results provide evidence that these lipid-degradation products primarily constitute markers of oxidative stress.

Vaginal bleeding in very early pregnancy.

INTRODUCTION: Little is known about the occurrence and patterns of vaginal bleeding during the earliest stages of pregnancy. We explore this in a prospective study of early pregnancy. METHODS: A total of 221 healthy women kept daily diaries and provided daily urine samples while trying to become pregnant. Of these, 151 women became clinically pregnant [i.e. pregnancy that lasted >/=6 weeks beyond last menstrual period (LMP)] during the study. Diaries provided information on days with vaginal bleeding and sexual intercourse. Urine hormone assays were used to identify ovulation and implantation. Women were interviewed about their medical histories and lifestyle factors. RESULTS: A total of 14 women (9%) recorded at least 1 day of vaginal bleeding during the first 8 weeks of pregnancy. Twelve of these 14 pregnancies continued to a live birth. Bleeding tended to occur around the time when women would expect their periods, although rarely on the day of implantation. Bleeding was not associated with intercourse. CONCLUSIONS: Early bleeding in clinical pregnancies is generally light, and not likely to be mistaken for LMP. Thus, early bleeding is unlikely to contribute to errors in LMP-based gestational age. We found no support for the hypothesis that implantation can produce vaginal bleeding. Similarly, intercourse did not cause bleeding. Nearly all women with bleeding went on to have successful pregnancies.

Natural limits of pregnancy testing in relation to the expected menstrual period.

CONTEXT: Pregnancy test kits routinely recommend testing "as early as the first day of the missed period." However, a pregnancy cannot be detected before the blastocyst implants. Due to natural variability in the timing of ovulation, implantation does not necessarily occur before the expected onset of next menses. OBJECTIVE: To estimate the maximum screening sensitivity of pregnancy tests when used on the first day of the expected period, taking into account the natural variability of ovulation and implantation. DESIGN AND SETTING: Community-based prospective cohort study conducted in North Carolina between 1982 and 1986. PARTICIPANTS: Two hundred twenty-one healthy women 21 to 42 years of age who were planning to conceive. MAIN OUTCOME MEASURES: Day of implantation, defined by the serial assay of first morning urine samples using an extremely sensitive immunoradiometric assay for human chorionic gonadotropin (hCG), relative to the first day of the missed period, defined as the day on which women expected their next menses to begin, based on self-reported usual cycle length. RESULTS: Data were available for 136 clinical pregnancies conceived during the study, 14 (10%) of which had not yet implanted by the first day of the missed period. The highest possible screening sensitivity for an hCG-based pregnancy test therefore is estimated to be 90% (95% confidence interval [CI], 84%-94%) on the first day of the missed period. By 1 week after the first day of the missed period, the highest possible screening sensitivity is estimated to be 97% (95% CI, 94%-99%). CONCLUSIONS: In this study, using an extremely sensitive assay for hCG, 10% of clinical pregnancies were undetectable on the first day of missed menses. In practice, an even larger percentage of clinical pregnancies may be undetected by current test kits on this day, given their reported assay properties and other practical limitations.

No evidence for lipid peroxidation in severe preeclampsia.

OBJECTIVE: This study was undertaken to address the role of oxidative stress in preeclampsia. STUDY DESIGN: We measured urinary 8,12-iso-iPF(2alpha)-VI, a chemically stable, free-radical catalyzed product, in a case control study of severe preeclampsia nested within the trial of Calcium for Preeclampsia Prevention. Cases included 29 women who developed severe preeclampsia and from whom urine had been obtained 10 to 20 weeks before the diagnosis of preeclampsia, 3 to 9 weeks before, and 1 day before through delivery. Controls did not develop hypertension or proteinuria and were matched to cases by center, gestational age at each of 3 corresponding urine collections, and date of enrollment. RESULTS: Urinary 8,12-iso -iPF(2alpha)-VI did not differ significantly between cases and controls before or at diagnosis of preeclampsia, nor did it vary with gestational age. CONCLUSIONS: These results call into question the importance of oxidative stress in the disease and the biochemical rationale for clinical trials of antioxidants to prevent and treat preeclampsia.

Development and reliability of a Telephone-Administered Perceived Racism Scale (TPRS): a tool for epidemiological use.

The conceptualization of perceived racism as a chronic stressor is relatively new to epidemiology. The Telephone-Administered Perceived Racism Scale (TPRS) captures the complexity of racism within five scales: Experience of Racism (by Blacks as a group and by the respondent), Emotional Responses, Behavioral Responses, Concern for Child(ren), and Past Experiences of Racism. The TPRS was developed for employed Black women. Exploratory factor analyses and tests of internal consistency were completed with 476 Black women, aged 36-53. Factor analyses on their responses to racism yielded five factors: passive emotions, active emotions, passive behaviors, internal active behaviors, and external active behaviors. Alpha reliability values ranged from 0.75 to 0.80 for the active and passive emotions subscales, from 0.59 to 0.69 for the passive behaviors subscale, and greater than 0.76 for both active behaviors subscales. Alpha reliabilities were 0.82, 0.90, 0.88, and 0.82 for Past Experiences, Concern for Child(ren), Experience of Racism--Personal, and Experience of Racism--Group, respectively. Another 30 Black women were queried for test-retest reliability, with values ranging from 0.61 to 0.82. The TPRS was found to be reliable and should serve as a useful epidemiological tool in the examination of the effects of perceived racism on Black women's health.

A flexible parametric model for combining current status and age at first diagnosis data.

In some cross-sectional studies of chronic disease, data consist of the age at examination, whether the disease was present at the exam, and recall of the age at first diagnosis. This article describes a flexible parametric approach for combining current status and age at first diagnosis data. We assume that the log odds of onset by a given age and of detection by a given age conditional on onset by that age are nondecreasing functions of time plus linear combinations of covariates. Piecewise linear models are used to characterize changes across time in the baseline odds. Methods are described for accommodating informatively missing current status data and inferences based on the age-specific incidence of disease prior to a landmark event (e.g., puberty, menopause). Our formulation enables straightforward maximum likelihood estimation without requiring restrictive parametric or Markov assumptions. The methods are applied to data from a study of uterine fibroids.