Michels, K. A., Mendola, P., Schliep, K. C., Yeung, E. H., Ye, A., Dunietz, G. L., Wactawski-Wende, J., Kim, K., Freeman, J. R., Schisterman, E. F., & Mumford, S. L. (2020). The influences of sleep duration, chronotype, and nightwork on the ovarian cycle. Chronobiology international, 37(2), 260-271. https://doi.org/10.1080/07420528.2019.1694938
Michels KA, Mendola P, Schliep KC, Yeung EH, Ye A, Dunietz GL, et al. The influences of sleep duration, chronotype, and nightwork on the ovarian cycle. Chronobiol Int. 2020;37(2):260-271. doi:10.1080/07420528.2019.1694938
Michels, K. A., et al. "The influences of sleep duration, chronotype, and nightwork on the ovarian cycle." Chronobiology international, vol. 37, no. 2, 2020, pp. 260-271.
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University at Buffalo, State University of New York01y64my43
Despite research indicating that sleep disorders influence reproductive health, the effects of sleep on reproductive hormone concentrations are poorly characterized. We prospectively followed 259 regularly menstruating women across one to two menstrual cycles (the BioCycle Study, 2005-2007), measuring fasting serum hormone concentrations up to eight times per cycle. Women provided information about daily sleep in diaries and chronotype and night/shift work on a baseline questionnaire. We evaluated percent differences in mean hormone concentrations, the magnitude of shifts in the timing and amplitude of hormone peaks, and the risk for sporadic anovulation associated with self-reported sleep patterns and night/shift work. We estimated chronotype scores - categorizing women below and above the interquartile range (IQR) as "morning" and "evening" chronotypes, respectively. For every hour increase in daily sleep duration, mean estradiol concentrations increased by 3.9% (95% confidence interval [CI] 2.0, 5.9%) and luteal phase progesterone by 9.4% (CI 4.0, 15.2%). Receiving less than 7 hours of sleep per day was associated with slightly earlier rises in peak levels for several hormones. Women reporting night/shift work (n = 77) had lower testosterone relative to women employed without night/shift work (percent difference: -9.9%, CI -18.4, -0.4%). Women with morning chronotypes (n = 47) had earlier rises in estradiol during their cycles and potentially an earlier rise in luteinizing hormone. Compared to those who had intermediate chronotypes, women with evening chronotypes (n = 42) had a later luteinizing hormone peak of borderline statistical significance. A reduced risk for sporadic anovulation was suggested, but imprecise, for increasing hours of daily sleep leading up to ovulation (risk ratio 0.79, CI 0.59, 1.06), while an imprecise increased risk was observed for women with morning chronotypes (risk ratio 2.50, CI 0.93, 6.77). Sleep-related hormonal changes may not greatly alter ovarian function in healthy women, but have the potential to influence gynecologic health.
Schliep KC et al., 2026·J Gynecol Obstet Hum Reprod·Free full text on PubMed Central
Endometriosis has been linked to cardiometabolic alterations, but whether these associations vary by disease severity or phenotype is unclear. We examined lipid profiles across endometriosis diagnosis, stage, and typology. Data came from 476 women in the NICHD ENDO cohort. Endometriosis was confirmed laparoscopically and staged using the rASRM criteria (I-IV). Typology was categorized as superficial endometriosis (SE), ovarian endometrioma (OE), deep infiltrating endometriosis (DE), and OE+DE. We compared endometriosis status, stage (I/II vs III/IV), and typology to no endometriosis using adverse lipid thresholds (total cholesterol ≥200 mg/dL, HDL <50 mg/dL, LDL ≥100 mg/dL, triglycerides ≥175 mg/dL, non-HDL ≥130 mg/dL, VLDL ≥30 mg/dL, ApoA1 <125 mg/dL, and ApoB ≥120 mg/dL). Adjusted prevalence ratios (aPR) and 95 % CIs were estimated via generalized linear models, controlling for age, race/ethnicity, BMI, income, marital status, and serum cotinine. Endometriosis diagnosis alone was not associated with adverse lipid profiles. In contrast, moderate/severe disease showed higher prevalence of elevated triglycerides (aPR= 2.27; 95 % CI: 1.18,4.35) and VLDL (aPR= 2.41; 95 % CI: 1.50, 3.85). Typology revealed stronger patterns: OE and OE+DE were associated with adverse profiles across multiple markers (aPRs 1.59-4.09), particularly ApoB and triglycerides. Minimal/mild disease and SE were not associated. The metabolic signal was phenotype-driven rather than diagnosis-driven, with severe stage and OE/OE+DE showing clear associations with adverse lipid profiles. These findings suggest lipid profiles may serve as markers of phenotype severity or shared biological milieu. Replication in larger cohorts is needed.
Reeder MR et al., 2026·Fertil Steril·Free full text on PubMed Central
To examine birth outcomes between children conceived with in vitro fertilization (IVF) or intrauterine insemination (IUI) and sibling births from unassisted conceptions. Retrospective sibling cohort. Live born children conceived via IVF, with or without intracytoplasmic sperm injection, or IUI at the Utah Center for Reproductive Medicine, 1999-2018, and sibling births from unassisted conceptions (born 1985-2018). The main analysis included singleton births (460 IVF, 666 IUI, and 1,579 unassisted siblings). Exposure: In vitro fertilization, with or without intracytoplasmic sperm injection, or IUI. Preterm birth, low birth weight, small for gestational age, large for gestational age (LGA), and major congenital anomalies. Compared with unassisted siblings, singleton children conceived via IVF had gestational ages shorter by nearly half a week (95% confidence interval [CI], -0.6 to -0.3), birth weights of 72.1 g lower (95% CI, -118.8 to -25.4), and higher proportions of preterm birth (IVF, 11.1%; IUI, 8.7%; unassisted siblings, 6.8%), LGA (IVF, 9.1%; IUI, 4.5%; unassisted siblings, 5.9%), and major congenital anomalies (IVF, 3.7%; IUI, 2.0%; unassisted siblings, 1.4%). Models adjusted for maternal age, infant sex, infant birth year, previous pregnancy, and birth order showed that children conceived via IVF were more likely to be preterm (adjusted risk ratio [aRR], 1.6; 95% CI, 1.2-2.2; absolute difference, 4.3%) and LGA (aRR, 1.8; 95% CI, 1.2-2.5; absolute difference, 3.2%). Children conceived via IVF had a higher risk of major congenital anomalies than unassisted siblings adjusted for maternal age, infant sex, and birth order (aRR, 1.9; 95% CI, 1.0-3.8; absolute difference, 2.3%). Children conceived via IUI had birth weights 55.8 g lower (95% CI, -95.6 to -15.9) than unassisted siblings. We observed an increased risk of preterm birth, low birth weight, LGA, and major congenital anomalies among singleton children conceived with IVF compared with that among unassisted siblings; however, absolute differences remain small. For children conceived via IUI, lower birth weights were observed. These results suggest that treatment-related factors in addition to underlying subfertility may contribute to adverse birth outcomes.
Valenti M et al., 2026·Am J Obstet Gynecol·Free full text on PubMed Central
Endometriosis is a chronic, gynecologic condition in which tissue similar to the lining of the uterus implants throughout the body. Women with endometriosis have a higher prevalence of infertility and a greater risk of early natural menopause compared to those without endometriosis. This study aimed to evaluate preoperative serum AMH levels among women with and without incident endometriosis and to assess whether levels differ by surgical staging and typology. The ENDO (Endometriosis: Natural History, Diagnosis, and Outcomes) study was conducted between 2007 and 2009. The ENDO study consisted of an operative and population cohort (n=600). Only those in the ENDO operative cohort from the Utah site were used for this analysis, and included women aged 18 to 44 years who were scheduled for gynecologic surgery, irrespective of clinical indication (n=476). AMH levels were measured from stored serum collected before surgery using a quantitative enzyme-linked immunosorbent assay. After excluding participants with missing outcome data (n=51), unilateral oophorectomy (n=8), or those within the population cohort (n=69), 348 participants remained for the analysis. Surgically confirmed endometriosis diagnosis, staging (American Society for Reproductive Medicine I-IV), and typology (superficial, deep, ovarian) were ascertained by the operative report. Outliers for AMH (>14.0 ng/mL) were excluded from the analyses and AMH values were log-transformed. Multivariable linear regression models adjusted for age (squared and continuous), body mass index, serum cotinine levels, and exogenous hormonal contraceptive use were conducted. Percentage differences in AMH were calculated as (exp[β]-1)×100, and 95% confidence intervals were reported. Compared with no endometriosis, incident endometriosis diagnosis was associated with lower AMH levels (-19.8%; 95% confidence interval, -37.0 to 1.0); however, this association was not statistically significant. Stage III to IV disease was associated with 40.1% lower AMH levels (95% confidence interval, -58.9 to -12.7). Ovarian endometriomas were most strongly associated with lower AMH levels (-54.3%; 95% confidence interval, -69.4 to -31.8), with a more pronounced association among those with infertility (-72.6%; 95% confidence interval, -85.4 to -48.5). Deep (-24.1%; 95% confidence interval, -48.2 to 11.0) and superficial (-15.5%; 95% confidence interval, -34.6 to 9.3) endometriosis also showed a trend toward lower AMH levels, but these findings were not statistically significant. Compared with a postoperative diagnosis of a normal pelvis, incident endometriosis was associated with 26.8% lower AMH levels (95% confidence interval, -44.6 to -3.4). Stage III to IV disease was associated with 47.8% lower AMH levels (95% confidence interval, -65.8 to -23.2), and all subtypes of endometriosis were statistically significantly associated with lower levels of AMH compared with a postoperative diagnosis of a normal pelvis (ovarian: -60.8%; 95% confidence interval, -74.4 to -39.9; deep: -34.3%; 95% confidence interval, -56.2 to -1.4; superficial: -24.8%; 95% confidence interval, -43.9 to -0.8). Ovarian and moderate to severe (stage III-IV) endometriosis were associated with markedly lower AMH levels compared with no endometriosis. Compared with a postoperative diagnosis of a normal pelvis, incident endometriosis and moderate to severe stages (stage III-IV) were associated with statistically significantly lower AMH levels. Additionally, typology (deep, ovarian, or superficial) was associated with statistically significantly lower AMH levels. However, this association was likely driven by the presence of ovarian endometriomas across all subtypes. These findings are consistent with previous studies and demonstrate that endometriosis lesions themselves, independent of surgical intervention, influence AMH levels.
Fertility and Outcomes · Conception After Excision
Hsu JZ et al., 2025·Eur J Obstet Gynecol Reprod Biol
Endometriosis is a chronic gynaecological condition affecting reproductive-aged women. It has been associated with infertility and potential risks for adverse pregnancy outcomes, although population-level evidence remains limited. This retrospective cohort study, including 147,950 pregnant women aged 20-45 years, used nationwide population-based data to compare the outcomes between women with (n = 11,400) and without (n = 136,550) endometriosis between 2000 and 2021. Baseline characteristics, comorbidities and pregnancy outcomes were compared between the groups. Multivariable regression analyses were performed to calculate adjusted relative risks (aRR) and 95 % confidence intervals (CI) for various pregnancy outcomes, and subgroup analyses were conducted by maternal age and infertility status. Among 147,950 pregnancies, women with endometriosis [mean ± standard deviation (SD) age 32.38 ± 4.51 years] had higher socio-economic status, more comorbidities, and more surgical history compared with women without endometriosis (mean ± SD age 30.06 ± 4.96 years). Women with endometriosis had increased risk of miscarriage (aRR 1.13, 95 % CI 1.03-1.24), preterm birth (aRR 1.31, 95 % CI 1.26-1.37), premature rupture of membranes (aRR 1.11, 95 % CI 1.06-1.16), placenta previa (aRR 1.63, 95 % CI 1.45-1.84), urinary tract infection (aRR 1.44, 95 % CI 1.31-1.59), and caesarean section (aRR 1.13, 95 % CI 1.11-1.16). Subgroup analysis revealed that risk of miscarriage was only higher in women aged 35-45 years and women without infertility. Risks of preterm birth, placenta previa and caesarean section were elevated across all subgroups, suggesting that endometriosis contributes independently to adverse pregnancy outcomes. Endometriosis is an independent risk factor for several pregnancy complications, supporting the need for tailored prenatal care and closer monitoring of affected women to improve maternal outcomes.
Lawson CC et al., 2011·Epidemiology (Cambridge, Mass.)·Free full text on PubMed Central
Shift workers who experience sleep disturbances and exposure to light at night could be at increased risk for alterations in physiologic functions that are circadian in nature. We investigated rotating shift work and menstrual cycle patterns in the Nurses' Health Study II using cross-sectional data collected in 1993 from 71,077 nurses aged 28-45 years who were having menstrual periods and were not using oral contraceptives. Log-binomial regression was used to estimate relative risks (RRs) and 95% confidence intervals (CIs). Eight percent of participants reported working rotating night shifts for 1-9 months, 4% for 10-19 months, and 7% for 20+ months during the previous 2 years. Irregular cycles (>7 days variability) were reported by 10% of participants. Seventy percent of women reported menstrual cycles of 26-31 days, 1% less than 21 days, 16% 21-25 days, 11% 32-39 days, and 1% 40+ days. Women with 20+ months of rotating shift work were more likely to have irregular cycles (adjusted RR = 1.23 [CI = 1.14-1.33]); they were also more likely to have cycle length <21 days (1.27 [0.99-1.62]) or 40+ days (1.49 [1.19-1.87]) (both compared with 26-31 days). For irregular patterns and for 40+ day cycles, there was evidence of a dose response with increasing months of rotating shift work. Moderately short (21-25 days) or long (32-39 days) cycle lengths were not associated with rotating shift work. Shift work was modestly associated with menstrual function, with possible implications for fertility and other cycle-related aspects of women's health.
12 h rotating shifts are common in high-tech industries in Taiwan. The aim of this longitudinal study was to evaluate the effect of the disruption of circadian rhythms by the shift schedule on menstrual cycle length (MCL) and regularity of female workers at an optoelectronic company in Taiwan. We recruited females who worked rotating shifts in a clean room environment as the shift-work group and female office workers who worked normal business hours as the comparison group. Every participant recorded their MCL for each menstruation cycle up to eight consecutive months prospectively and provided demographic characteristics, reproductive history, and menstrual characteristics. We collected data on 1,135 and 117 menstruation cycles in the shift-work (n = 280) and comparison groups (n = 49). Whereas the two groups had similar group means for MCL and number of menstrual bleeding days, the prevalence of menstrual cycle irregularity (cycles <25 or >35 days) was higher in the shift-work group ( p = 0.04). Univariate and multivariate logistic regression analyses demonstrated that rotating shift work was an independent predictor of menstrual cycle irregularity (odds ratio = 1.71, 95% confidence interval: 1.03-2.88) after adjusting for shift-work history, employment duration, coffee consumption,and pre-employment menstrual cycle irregularity. Although further study is required to confirm our findings plus to explore prevention and control measures, our data indicate rotating shift work can increase the risk of MCL irregularity.
Women with ovulatory menstrual cycles have a circadian rhythm superimposed on the menstrual-associated rhythm; in turn, menstrual events affect the circadian rhythm. In this paper, we review circadian rhythms in temperature, selected hormone profiles, and sleep-wake behavior in healthy women at different phases of the menstrual cycle. The effects on menstrual cycle rhythmicity of disrupted circadian rhythms, for example, with shiftwork and altered circadian rhythms in women with menstrual-related mood disturbances, are discussed. Compared to the follicular phase, in the post-ovulation luteal phase, body temperature is elevated, but the amplitude of the temperature rhythm is reduced. Evidence indicates that the amplitude of other rhythms, such as melatonin and cortisol, may also be blunted in the luteal phase. Subjective sleep quality is lowest around menses, but the timing and composition of sleep remains relatively stable across the menstrual cycle in healthy women, apart from an increase in spindle frequency activity and a minor decrease in rapid eye movement (REM) sleep during the luteal phase. Disruption of circadian rhythms is associated with disturbances in menstrual function. Female shiftworkers compared to non-shiftworkers are more likely to report menstrual irregularity and longer menstrual cycles. There also is accumulating evidence that circadian disruption increases the risk of breast cancer in women, possibly due to altered light exposure and reduced melatonin secretion. Further investigations into the biological consequences of circadian disruption in women will offer insight into some menstrual-associated disorders, including mood changes, as well as reproductive function and possible links with breast cancer.
Hatch MC et al., 1999·Scandinavian journal of work, environment & health·Free to read
This study assessed whether job stress alters menstrual patterns among nurses working in 2 different settings: a tertiary care hospital in New York (99 nurses) and a university hospital in Rome (25 nurses). Data on menstrual patterns were collected by a daily diary in which the nurses recorded their basal body temperature (BBT) and their menstrual bleeding status for a 3-month period. The BBT curves were used to classify cycles as biphasic or monophasic, and as adequate or inadequate with respect to the luteal phase. Job stress was evaluated by both objective (environmental and work characteristics) and subjective (perceived stress) criteria. The American nurses, especially those assigned to high stress units, had an increased risk for long and monophasic cycles [relative risk (RR) 4.3, 95% confidence interval (95% CI) 1.1-16.2 and RR 5.5, 95% CI 1.2-25.5, respectively]. Among those who perceived their stress at work to be high or reported strenuous work activity, the risk for longer cycles was also raised (RR 2.3, 95% CI 0.6-8.0 and RR 1.6, 95% CI 0.7-4.2, respectively). Luteal phase inadequacy followed the same pattern. Similar trends were observed in the Italian data. In addition, the rotating shiftwork pattern prevalent in the Italian group was possibly associated with higher rates of short cycles and inadequate luteal phases when compared with those of nurses working fixed shifts either day or night. Menstrual function may be affected by stressful work conditions.
Menstrual Cycle › Cycle Physiology › Hormonal Regulation · Lifestyle and Environment › Sleep and Circadian Health › Shift Work and Light Exposure · Reproductive Endocrinology › Ovarian Hormones › Estrogen
Pauline Mendola, Karen C Schliep, Galit L Dunietz, Keewan Kim, Joshua R Freeman, Enrique F Schisterman, Kara A Michels, Sunni L Mumford, Jean Wactawski-Wende, Aijun Ye, Edwina H Yeung
P Mendola, K Schliep, G Dunietz, K Kim, Josh Freeman, J Freeman, E Schisterman, K Michels, S Mumford, J Wactawski-Wende, A Ye, E Yeung
PMID 31778080 31778080 DOI 10.1080/07420528.2019.1694938 10.1080/07420528.2019.1694938 Michels et al. 2020, Michels 2020
Cite this article
Michels, K. A., Mendola, P., Schliep, K. C., Yeung, E. H., Ye, A., Dunietz, G. L., Wactawski-Wende, J., Kim, K., Freeman, J. R., Schisterman, E. F., & Mumford, S. L. (2020). The influences of sleep duration, chronotype, and nightwork on the ovarian cycle. Chronobiology international, 37(2), 260-271. https://doi.org/10.1080/07420528.2019.1694938
Michels KA, Mendola P, Schliep KC, Yeung EH, Ye A, Dunietz GL, et al. The influences of sleep duration, chronotype, and nightwork on the ovarian cycle. Chronobiol Int. 2020;37(2):260-271. doi:10.1080/07420528.2019.1694938
Michels, K. A., et al. "The influences of sleep duration, chronotype, and nightwork on the ovarian cycle." Chronobiology international, vol. 37, no. 2, 2020, pp. 260-271.
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