Why so null? Methodologic necessities to advance endometriosis discovery

Early Detection of Ovarian Cancer

The risk of death from ovarian cancer is highly associated with the clinical stage at diagnosis. Efforts to implement screening for ovarian cancer have been largely unsuccessful, due to the low prevalence of the disease in the general population and the heterogeneity of the various cancer types that fall under the ovarian cancer designation. A practical test for early detection will require both high sensitivity and high specificity to balance reducing the number of cancer deaths with minimizing surgical interventions for false positive screens. The technology must be cost-effective to deliver at scale, widely accessible, and relatively noninvasive. Most importantly, a successful early detection test must be effective not only at diagnosing ovarian cancer but also in reducing ovarian cancer deaths. Stepwise or multimodal approaches among the various areas under investigation will likely be required to make early detection a reality.

How to Improve Non-Invasive Diagnosis of Endometriosis with Advanced Statistical Methods

Background and Objectives: Endometriosis is one of the most common gynecological disorders in women of reproductive age. Causing pelvic pain and infertility, it is considered one of the most serious health problems, being responsible for work absences or productivity loss. Its diagnosis is often delayed because of the need for an invasive laparoscopic approach. Despite years of studies, no single marker for endometriosis has been discovered. The aim of this research was to find an algorithm based on symptoms and laboratory tests that could diagnose endometriosis in a non-invasive way. Materials and Methods: The research group consisted of 101 women hospitalized for diagnostic laparoscopy, among which 71 had confirmed endometriosis. Data on reproductive history were collected in detail. CA125 (cancer antigen-125) level and VEGF1(vascular endothelial growth factor 1) were tested in blood samples. Among the used statistical methods, the LASSO regression-a new important statistical tool eliminating the least useful features-was the only method to have significant results. Results: Out of 19 features based on results of LASSO, 7 variables were chosen: body mass index, age of menarche, cycle length, painful periods, information about using contraception, CA125, and VEGF1. After multivariate logistic regression with a backward strategy, the three most significant features were evaluated. The strongest impact on endometriosis prediction had information about painful periods, CA125 over 15 u/mL, and the lowest BMI, with a sensitivity of 0.8800 and a specificity of 0.8000, respectively. Conclusions: Advanced statistical methods are crucial when creating non-invasive tests for endometriosis. An algorithm based on three easy features, including painful menses, BMI level, and CA125 concentration could have an important place in the non-invasive diagnosis of endometriosis. If confirmed in a prospective study, implementing such an algorithm in populations with a high risk of endometriosis will allow us to cover patients suspected of endometriosis with proper treatment.

Trends in pelvic pain symptoms over 2 years of follow-up among adolescents and young adults with and without endometriosis

ABSTRACT

We described trends in pelvic pain characteristics over 2 years of follow-up among adolescents and adults with and without endometriosis participating in the longitudinal observational cohort of the Women's Health Study: From Adolescence to Adulthood, using data reported at baseline and at years 1 and 2 of follow-up. Participants completed a questionnaire at baseline (between November 2012 and May 2019) and annually thereafter that included validated measures of severity, frequency, and life interference of dysmenorrhea, acyclic pelvic pain, and dyspareunia. Our study population included 620 participants with surgically confirmed endometriosis (rASRM stage I/II = 95%) and 671 community-based and hospital-based controls, with median age = 19 and 24 years, respectively. The proportion reporting hormone use varied across the 3 years ranging from 88% to 92% for cases and 56% to 58% for controls. At baseline, endometriosis cases were more likely to report severe, frequent, and life-interfering dysmenorrhea, acyclic pelvic pain, and dyspareunia compared with controls. Among cases, frequency and severity of dysmenorrhea and dyspareunia were relatively static across 2 years. However, acyclic pelvic pain improved. Severe acyclic pain decreased from 69% at baseline to 46% at year 2. Daily pain decreased from 28% to 14%, and life interference from 68% to 38%. Trends among controls remained fairly stable across 2 years. Among endometriosis cases who completed the questionnaire at all 3 time points, 18% reported persistent, severe acyclic pelvic pain at all 3 time points. Over time, different trends were observed by pelvic pain type among endometriosis cases and controls, supporting the importance of assessing multidimensional features of pelvic pain.

Pesticide residue intake from fruit and vegetable consumption and risk of laparoscopically confirmed endometriosis

OBJECTIVE

To examine the association between the intake of fruits and vegetables with high- vs. low-pesticide residue burden and diagnosis of laparoscopically confirmed endometriosis. The etiology of endometriosis is not well understood, but dietary factors may influence the risk. Pesticides may act as endocrine disruptors, and the intake of pesticide-contaminated food is a common exposure pathway.

DESIGN

Prospective cohort study. Hazard ratios and 95% confidence intervals were calculated using multivariable Cox proportional hazard models to evaluate the intake of fruits and vegetables with high- and low-pesticide residues in relation to the diagnosis of laparoscopically confirmed endometriosis.

SETTING

Not applicable.

PATIENT(S)

Premenopausal US women (N = 52,053) of the Nurses' Health Study II, aged 34-53 years at study baseline (1999), were followed until 2013. The diet was assessed every 4 years using a validated food frequency questionnaire. A previously developed and validated pesticide residue burden score (PRBS), on the basis of the US Department of Agriculture Pesticide Data Program, was used to assign fruits and vegetables to pesticide residue groups (high/low).

INTERVENTION(S)

Not applicable.

MAIN OUTCOME MEASURE(S)

Cases of laparoscopically confirmed endometriosis were identified from self-reports to validated questionnaires.

RESULT(S)

During 14 years of follow-up, 956 incidences of laparoscopically confirmed endometriosis were reported. No association was observed between the intake of high- or low-PRBS fruit and vegetable intake and endometriosis (hazard ratio for 5th vs. 1st quintile: high-PRBS intake = 0.94, 95% confidence interval = 0.73-1.23; low-PRBS intake = 1.07, 95% confidence interval = 0.82-1.40). No associations were observed for high- or low-PRBS fruit and vegetable intake by fertility status.

CONCLUSION(S)

No clear associations were observed between high- or low-PRBS fruit and vegetable intake and endometriosis risk among premenopausal women. To our knowledge, this is the first study to evaluate the association between dietary pesticide residue intake and endometriosis. Further research is needed, particularly to evaluate this association among a younger population of women (adolescence or early adulthood) and assess the dietary exposure to specific pesticides or chemical families.

Circulating proteomic profiles associated with endometriosis in adolescents and young adults

STUDY QUESTION

What are the systemic molecular profiles of endometriosis diagnosed in adolescents and young adults?

SUMMARY ANSWER

Significant enrichment and increased activation of proteins related to angiogenesis and cell migration pathways were observed in endometriosis cases compared to controls (P-value < 2.4 × 10-8).

WHAT IS KNOWN ALREADY

Little is known about the pathophysiology of adolescent endometriosis despite the fact that over 50% of adults with endometriosis report onset of severe pelvic pain during adolescence.

STUDY DESIGN, SIZE, DURATION

A cross-sectional analysis using data on 142 laparoscopically confirmed endometriosis cases and 74 controls from the observational longitudinal cohort of Women's Health Study: From Adolescence to Adulthood (A2A).

PARTICIPANTS/MATERIALS, SETTING, METHODS

We measured 1305 plasma protein levels using the validated, multiplex aptamer-based proteomics discovery platform, SOMAscan. We calculated odds ratios and 95% CIs using logistic regression adjusting for age, BMI, fasting status and hormone use at blood draw for differentially expressed proteins (P < 0.05). Ingenuity Pathway Analysis and STRING analysis were performed to identify biological pathways and protein interactions. We also examined proteins and pathways associated with superficial peritoneal lesion colors (i.e. red, vascularized, white, blue/black, brown).

MAIN RESULTS AND THE ROLE OF CHANCE

Average age at blood draw was 18 years for endometriosis cases and 22 years for controls. We identified 63 proteins associated with endometriosis with type-I error set at 0.05, and absolute fold change >1.2, revealing significant enrichment of dysregulated proteins in biological pathways associated with endometriosis. Increased activation of pathways related to angiogenesis and cell migration was observed in plasma from endometriosis cases compared to controls (P-value < 2.4 × 10-8). Furthermore, when we examined proteins and pathways associated with lesion colors, vascularized lesions were associated with upregulation of pathways related to immune cell migration/activation and inflammation, whereas white, blue/black and brown lesions were associated with downregulation of these pathways.

LIMITATIONS, REASONS FOR CAUTION

Validation of our results in independent datasets and mechanistic studies are warranted to further our understanding of the pathophysiological characteristics of this common but understudied patient population.

WIDER IMPLICATIONS OF THE FINDINGS

To our knowledge, this was the first study to comprehensively examine circulating proteins in predominantly adolescents and young adult women with and without endometriosis. Results from this study provide novel biological insight that will build toward further research to elucidate endometriosis pathophysiology during the earlier course of the disease trajectory.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the Department of Defense (W81XWH1910318) and the 2017 Boston Center for Endometriosis Trainee Award. Financial support for establishment of and data collection within the A2A cohort were provided by the J. Willard and Alice S. Marriott Foundation. N.S., A.F.V., S.A.M., K.L.T. have received funding from Marriott Family Foundation. S.A.M. and K.L.T. are supported by NICHD (R01 HD94842). S.A.M. serves as an advisory board member for AbbVie and Roche; neither are related to this study. The authors report no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Pregnancy outcomes among women with endometriosis and fibroids: registry linkage study in Massachusetts

BACKGROUND

Endometriosis and uterine fibroids are common gynecologic conditions associated with a greater risk for infertility. Previous research has suggested that these conditions are associated with adverse pregnancy outcomes, potentially because of increased utilization of fertility treatments.

OBJECTIVE

Our objective was to investigate whether women with a history of endometriosis or fibroids had a greater risk for adverse pregnancy outcomes and whether this risk varied by infertility history and fertility treatment utilization.

STUDY DESIGN

Deliveries (2013-2017) recorded in Massachusetts' vital records were linked to assisted reproductive technology data, hospital stays, and all-payer claims database. We identified endometriosis and fibroids diagnoses via the all-payer claims database before index delivery. Adjusted relative risks for pregnancy complications were modeled using generalized estimating equations with a log link and Poisson distribution. The influence of subfertility or infertility and assisted reproductive technology was also investigated.

RESULTS

Among 91,825 deliveries, 1560 women had endometriosis and 4212 had fibroids. Approximately 30% of women with endometriosis and 26% of women with fibroids experienced subfertility or infertility without utilizing assisted reproductive technology, and 34% of women with endometriosis and 21% of women with fibroids utilized assisted reproductive technology for the index delivery. Women with a history of endometriosis or fibroids were at a greater risk for pregnancy-induced hypertension, preeclampsia, or eclampsia (endometriosis relative risk, 1.17; fibroids relative risk, 1.08), placental abnormalities (endometriosis relative risk, 1.65; fibroids relative risk, 1.38), and cesarean delivery (endometriosis relative risk, 1.22; fibroids relative risk, 1.17) than women with no history of those conditions. Neonates born to women with a history of endometriosis or fibroids were also at a greater risk for preterm birth (endometriosis relative risk, 1.24; fibroids relative risk, 1.17). Associations between fibroids and low birthweight varied by fertility status or assisted reproductive technology (P homogeneity=.01) and were stronger among noninfertile women.

CONCLUSION

Endometriosis or fibroids increased the risk for adverse pregnancy outcomes, possibly warranting differential screening or treatment.

Association between endometriosis and lower urinary tract symptoms

OBJECTIVE

To determine if women with endometriosis experience lower urinary tract symptoms (LUTSs) more often than those without.

DESIGN

Cross-sectional analysis at enrollment in a longitudinal cohort.

SETTING

Enrollment at 2 academic hospitals and from the local community.

PATIENT(S)

This analysis included 1,161 women with (n = 520) and without (n = 641) surgically confirmed endometriosis who were enrolled in the Women's Health Study: from Adolescence to Adulthood between 2012 and 2018.

INTERVENTION(S)

Not applicable.

MAIN OUTCOME MEASURE(S)

Prevalence of LUTSs, including stress incontinence, urgency and frequency, straining with urination, incomplete bladder emptying, hematuria, dysuria, and bladder pain using standardized questionnaires.

RESULT(S)

The primary outcomes were that women with endometriosis reported the following more often than those without: difficulty passing urine (7.9% vs. 2%; crude odds ratio [OR], 4.14 [95% confidence interval {CI}, 2.19-7.80]; adjusted OR [aOR], 4.31 [95% CI, 2.07-8.95]); still feeling full after urination (18.8% vs. 4.7%; crude OR, 4.73 [95% CI, 3.08-7.25]; aOR, 4.67 [95% CI, 2.88-7.56]); having to urinate again within minutes of urinating (33.1% vs. 17.0%; crude OR, 2.41 [95% CI, 1.83-3.18]; aOR, 2.49 [95% CI, 1.81-3.43]), dysuria (11.7% vs. 4.9%; crude OR, 2.55 [95% CI, 1.62-4.01]; aOR, 2.38 [95% CI, 1.40-4.02]); and pain when the bladder is full (23.0% vs. 4.9%; crude OR, 5.79 [95% CI, 3.82-8.78]; aOR, 6.04 [95% CI, 3.74-9.76]). For the secondary outcomes, among female participants with endometriosis, we observed that the odds of LUTS did not differ by the revised American Society for Reproductive Medicine stage (I/II vs. III/IV) or duration of endometriosis-associated symptoms.

CONCLUSION(S)

Women with surgically confirmed endometriosis were more likely to report LUTS than those without.

Associations between body mass index and the surgical phenotype and location of endometriotic lesions

RESEARCH QUESTION

Is there a relationship between body mass index (BMI) and endometriotic lesions, specifically surgical phenotype and lesion location?

DESIGN

An observational retrospective cohort study at the Royal Women's Hospital, Melbourne, Australia, including 471 histologically confirmed endometriosis patients. Statistical analyses included multivariate logistic regression and multivariate modelling, correcting for multiple testing. Outcomes were the presence or absence of surgically classified lesion phenotypes, as per revised American Society for Reproductive Medicine criteria including superficial or deep, peritoneal or ovarian, and adhesions (Study I); and lesions at specific anatomical locations (including pelvic side wall, uterosacral ligament, pouch of Douglas, ovarian, uterovesical fold, bladder, and pararectal endometriosis) (Study II).

RESULTS

In Study I, patients with higher BMI were more likely to have superficial peritoneal lesions (odds ratio [OR] 1.070, 95% confidence interval [CI] 1.004-1.144; P = 0.044), and less likely to have deep ovarian lesions (OR 0.928, 95% CI 0.864-0.993; P = 0.034). In Study II, patients with higher BMI were less likely to have uterovesical fold lesions (OR 0.927, 95% CI 0.867-0.985; P = 0.021) or anterior compartment lesions (OR 0.940, 95% CI 0.888-0.989; P = 0.023). After correcting for multiple testing, the relationship between BMI and lesion phenotypes did not persist (P > 0.01).

CONCLUSIONS

This analysis does not conclusively support an influence of BMI on endometriotic lesion phenotype based on surgical classification or location. Further investigation of the physiological disturbances underlying BMI and the promotion of endometriotic lesion phenotypes and their location is warranted, but any effect is likely to be small.

Endometriosis and cancer: a systematic review and meta-analysis

BACKGROUND

Endometriosis is an often chronic, inflammatory gynaecologic condition affecting 190 million women worldwide. Studies have reported an elevated cancer risk among patients with endometriosis. However, prior research has included methodologic issues that impede valid and robust interpretation.

OBJECTIVE AND RATIONALE

We conducted a meta-analysis of studies investigating the association between endometriosis and cancer risk and analysed the results by methodologic characteristics. We discuss the implications of cancer screening in patients and management challenges faced by clinicians.

SEARCH METHODS

We searched PubMed and Embase databases for eligible studies from inception through 24 October 2019. We included cohort and case-control studies examining the association between endometriosis and cancer risk; cross-sectional studies and case reports were excluded. Publications had to present risk/rate/odds estimates with 95% CI. Random effects meta-analysis was used to estimate summary relative risks (SRR) and CIs. Heterogeneity across studies was assessed by the Q test and I2 statistics, and publication bias using Egger's and Begg's tests. Risk of bias and quality of the included studies were assessed using the risk of bias in non-randomized studies of interventions (ROBINS-I) tool.

OUTCOMES

Forty-nine population-based case-control and cohort studies were included. Twenty-six studies were scored as having a 'serious'/'critical' risk of bias, and the remaining 23 'low'/'moderate'. Cancer-specific analyses showed a positive association between endometriosis and ovarian cancer risk (SRR = 1.93, 95% CI = 1.68-2.22; n = 24 studies) that was strongest for clear cell (SRR = 3.44, 95% CI = 2.82-4.42; n = 5 studies) and endometrioid (SRR = 2.33, 95% CI = 1.82-2.98; n = 5 studies) histotypes (Pheterogeneity < 0.0001), although with significant evidence of both heterogeneity across studies and publication bias (Egger's and Begg's P-values < 0.01). A robust association was observed between endometriosis and thyroid cancer (SRR = 1.39, 95% CI =1.24-1.57; n = 5 studies), a very small association with breast cancer (SRR = 1.04, 95% CI =1.00-1.09; n = 20 studies) and no association with colorectal cancer (SRR = 1.00, 95% CI =0.87-1.16; n = 5 studies). The association with endometrial cancer was not statistically significant (SRR = 1.23, 95% CI =0.97-1.57; n = 17 studies) overall and wholly null when restricted to prospective cohort studies (SRR = 0.99, 95% CI =0.72-1.37; n = 5 studies). The association with cutaneous melanoma was also non-significant (SRR = 1.17, 95% CI =0.97-1.41; n = 7 studies) but increased in magnitude and was statistically significant when restricted to studies with low/moderate risk of bias (SRR = 1.71, 95% CI = 1.24-2.36, n = 2 studies). The most robust finding both in terms of statistical significance and magnitude of effect was an inverse association with cervical cancer (SRR = 0.68, 95% CI =0.56-0.82; n = 4 studies); however, this result has a high potential to reflect heightened access to detection of dysplasia for women who reached an endometriosis diagnosis and is thus likely not causal. Several additional cancer types were explored based on <4 studies.

WIDER IMPLICATIONS

Endometriosis was associated with a higher risk of ovarian and thyroid, and minimally (only 4% greater risk) with breast cancer, and with a lower risk of cervical cancer. However, this meta-analysis confirms that: a majority of studies had severe/critical risk of bias; there is impactful heterogeneity across studies-and for ovarian cancer, publication bias; and causal inference requires temporality, which in many studies was not considered. We discuss the implications of these potential associations from the perspectives of patients with endometriosis, clinicians involved in their care, and scientists investigating their long-term health risks.

Evaluation of CA125 in relation to pain symptoms among adolescents and young adult women with and without surgically-confirmed endometriosis

Endometriosis is a painful gynecologic disease affecting one in ten reproductive aged women worldwide. Few studies have correlated this symptomatology with biomarker levels among women with and without endometriosis, and no studies correlating pain with biomarker levels have been performed in young patient populations. The purpose of this study was to examine whether CA125 correlates with different types and severity of pain among adolescents and young women with and without endometriosis and assess its performance as an endometriosis biomarker among those presenting with dysmenorrhea in this young population. Reproductive-aged women with laparoscopically-confirmed endometriosis (n = 282) and controls (n = 293) who participated in The Women's Health Study: From Adolescence to Adulthood (A2A), a cohort of adolescents and young women enrolled from 2012-2018, were included in this cross-sectional analysis. Plasma CA125 values were measured using WERF EPHect compliant blood samples collected at enrollment. Average CA125 were calculated by self-reported pain type (i.e. dysmenorrhea, non-cyclic/general pelvic pain, dyspareunia), severity, and frequency in endometriosis cases and controls. Median age at blood draw was 24 years in controls and 17 years in cases, with 68% and 89% non-Hispanic white, respectively. Most endometriosis cases (95%) were rASRM stage I/II. Average CA125 values were 12.5 U/mL in controls and 12.1 U/mL in cases adjusted for age. CA125 did not differ by pain type, its severity, or frequency in endometriosis cases or controls. Among participants who reported dysmenorrhea, CA125 did not discriminate endometriosis cases from controls using cutoff of 35 U/mL (AUC = 0.51, 95%CI = 0.50-0.53). Among adolescents and young adult women, CA125 did not correlate with pain type. CA125 did not efficiently discriminate endometriosis cases from controls even when accounting for pain symptomatology. Average CA125 values were low in adolescents and young women in both endometriosis cases and controls, suggesting cautious interpretation may be needed when measuring CA125 in this population.

In utero and early life exposures in relation to endometriosis in adolescents and young adults

OBJECTIVE

Endometriosis is a common gynecologic disorder often associated with severe pelvic pain and infertility with few known modifiable risk factors. We investigated whether in utero and early life exposures are associated with surgically diagnosed endometriosis among adolescents and young adults.

STUDY DESIGN

This case-control study, including 295 laparoscopically-confirmed endometriosis cases and 309 population-based controls aged <25 years, was conducted using data from The Women's Health Study: From Adolescence to Adulthood which enrolled participants from 2012 to 2018. Information on in utero and early life factors were collected using a modified WERF EPHect questionnaire at enrollment, including their mother's age at delivery, birthweight, gestation length, exposure to smoking in utero and secondhand smoke during childhood up to age 13, and if the participant was breastfed.

RESULTS

Median age at enrollment was 17 years (range 12-24) in cases and 22 years (range 7-24) in controls, with 83 % and 68 % non-Hispanic whites, respectively. The majority of cases (95 %) were rASRM stage I or II at diagnostic surgery. Exposure to breastfeeding in early life was associated with lower odds of endometriosis diagnosis (OR = 0.39, 95 % CI = 0.21-0.74). Exposure to secondhand smoke during childhood due to maternal smoking was associated with increased odds of endometriosis diagnosis (OR = 2.70, 95 % CI = 1.11-6.60).

CONCLUSIONS

Among adolescents and young adults, our data suggest exposures to breastfeeding in early life and secondhand smoke during childhood may be associated with endometriosis risk, providing insight into etiologic pathways to be explored in this young population.

Peripheral Blood Leukocyte Telomere Length and Endometriosis

Endometriosis is a common gynecologic disease defined by the presence of endometrial-like tissue outside the uterine cavity. While its etiology is largely unknown, accumulating evidence suggests that inflammation plays a major role. Our objective was to investigate the association between peripheral blood leukocyte telomere length (LTL) and endometriosis using data from two large population-based studies, the New England Case-Control Study (NEC; n = 877) and the National Health and Nutrition Examination Survey (NHANES; n = 2268). NEC control participants were identified through a combination of random digit dialing, drivers' license lists, and town resident lists. In NHANES, selection algorithms were used to identify a nationally representative sample. Blood samples and demographic, reproductive, and health-related information were available from both data sources. Endometriosis was defined as self-reported of physician-diagnosed endometriosis. LTL was measured using quantitative polymerase chain reaction. Multivariable logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI) for the association between LTL and endometriosis. Shorter LTL was associated with greater odds of history of endometriosis. In NEC, women with the shortest LTL tertile compared with the longest had a 2.5-fold greater odds of endometriosis (OR_T3/T1 = 2.56, 95% CI = 1.16-5.63; p value, test for linear trend = 0.02). The association was stronger among women who usually experienced moderate or severe menstrual pain (OR _T3/T1 = 3.50, 95% CI = 1.12-10.97). In NHANES, the data suggested a similar but attenuated association (OR_T3/T1 = 1.29, 95% CI = 0.85-1.96). The observed associations in NEC suggest that shorter LTL may be associated with greater odds of endometriosis. A better understanding of how LTL influences endometriosis risk could elucidate novel disease pathophysiology.

Adverse Pregnancy Outcomes in Endometriosis - Myths and Realities

PURPOSE OF REVIEW

There is increasing interest in the long-term health and comorbid conditions associated with endometriosis for both women and neonates. The purpose of this review was to synthesize and discuss the current state of the literature investigating endometriosis and risk of adverse pregnancy outcomes.

RECENT FINDINGS

Methodologic considerations for studying endometriosis and adverse pregnancy outcomes include complexities regarding the comparison population, endometriosis definition, sample size, residual confounding, and interactions. The current research on endometriosis and adverse pregnancy outcomes should be interpreted cautiously. To date, evidence suggests that endometriosis may be associated with higher risk of ectopic pregnancy, placenta previa, preterm birth, and cesarean section. While an association with miscarriage and stillbirth has been consistently observed, the relative risk was small.

SUMMARY

Pregnant women with endometriosis may be at higher risk for certain adverse pregnancy outcomes and may therefore benefit from additional monitoring. However, additional research is needed to confirm these associations and should focus on ensuring studies have internal and external validity, as well as, investigate the potential for differences in endometriosis phenotypes. Moreover, future research should focus on understanding potential mechanisms of association and better understanding how early interventions, through increased monitoring or screening during pregnancy, may improve outcomes.