To systematically review and perform a meta-analysis of the risk of ectopic pregnancy in endometriosis.
Data Sources
MEDLINE (OVID), Embase (OVID), CINAHL (EBSCO), and Cochrane Library to April 1, 2019. Inclusion criteria were cohort or case-control studies from 1990 onward. Exclusion criteria were cohort studies without controls, case reports or series, or no English full-text.
Methods of Study Selection
A total of 1361 titles/abstracts were screened after removal of duplicates, 39 full-texts were requested, and, after 24 studies were excluded, there were 15 studies in the meta-analysis.
Tabulation, Integration, and Results
Data were extracted using standardized spreadsheets with 2 independent reviewers, and conflicts were resolved by a third reviewer. We performed random effects calculation of weighted estimated average odds ratio (OR). Heterogeneity and publication bias were assessed with the I2 metric and funnel plots/Egger's test, respectively. The Ottawa-Newcastle Quality Assessment Scale was used with a cutoff of ≥7 for higher quality. There were 10 case-control studies (17 972 ectopic pregnancy cases and 485 266 nonectopic pregnancy controls) and 5 cohort studies (30 609 women with endometriosis and 107 321 women without endometriosis). For case-control studies, endometriosis was associated with increased risk of ectopic pregnancy with an OR of 2.66 (95% confidence interval [CI] = 1.14-6.21, p = .02). For cohort studies, the OR was 0.95 (95% CI = 0.29-3.11, p = .94), but after post hoc analysis of the studies with a Ottawa-Newcastle score ≥7, the OR was 2.16 (95% CI = 1.67-2.79, p <.001). For both case-control and cohort studies, there was high heterogeneity among studies (I2 = 93.9% and I2 = 96.6%, Q test p <.001) but no obvious evidence of systematic bias in the funnel plot, and Egger's test results were not significant (p = .35, p = .70), suggesting no strong publication bias. There were insufficient data to make any conclusions with respect to anatomic characteristics of endometriosis (e.g., stage) or mode of conception (e.g., assisted reproductive technology vs spontaneous).
Conclusion
Possible evidence of an association between endometriosis and ectopic pregnancy was observed (OR = 2.16-2.66). However, these results should be considered with caution, owing to high heterogeneity among studies. Continued research is needed to delineate the pregnancy implications of endometriosis.
Rojas HE et al., 2026·Journal of women's health (2002)
To characterize differences between individuals with and without mid-cycle pain in a registry cohort with endometriosis. Prospective analysis of data from the Endometriosis Pelvic Pain Interdisciplinary Cohort Data Registry (Clinicaltrials.gov #NCT02911090) at a tertiary referral center in Western Canada. Three hundred forty-five individuals aged 18-49 years who: (1) had at least one episode of menstrual bleeding in the last 3 months, (2) attended a baseline initial visit, and (3) subsequently had surgery with histological confirmation of endometriosis between January 2018 and December 2023. Exclusion criteria included (1) previous hysterectomy; (2) hormonal suppressive therapy use in the last 3 months; and (3) missing data on mid-cycle pain, history of hormonal therapy use, or menstrual cycle regularity. N/A. Mid-cycle pain in the last month versus No mid-cycle pain in the last month. Of the 345 participants, 67% (n = 232) reported mid-cycle pain in the last month. Mid-cycle pain in the last month was significantly associated with higher mean Central Sensitization Inventory score (48 ± 17 versus 36 ± 16, p < 0.001) and more months of prior hormonal suppressive therapy use (58 [14-120] versus 26 [0-109], p = 0.012). Abnormal anatomy at the time of surgery (e.g., endometrioma, ovarian adhesions) was not associated with mid-cycle pain in the last month. In this endometriosis cohort at a tertiary referral center, most participants reported mid-cycle pain in the last month, which was associated with central sensitization but was not clearly related to endometriosis anatomical distortion.
Bouchard TP et al., 2026·Reproductive biomedicine online·Free to read
Do quantitative urinary hormone measurements on the Mira monitor predict and confirm ovulation accurately compared with ultrasound in women with regular menstrual cycles? Do Mira urine hormones correlate with serum hormones?
This was a prospective, single-centre, blinded diagnostic accuracy study with 52 women aged 19-44 years with regular cycles (24-38 days) who tracked 153 cycles over 18 months. Daily first-morning urine was tested with the Mira monitor for follicle stimulating hormone (FSH), oestrone-3-glucuronide (E13G), luteinizing hormone (LH) and pregnanediol glucuronide (PDG). Serial transvaginal ultrasounds (890 scans) confirmed the day of ovulation. Serum hormones were measured twice per cycle. The 121 ovulatory cycles from 49 participants with sufficient index test and reference standard data were included in the final analysis.
The Mira LH peak day strongly predicted ultrasound-confirmed ovulation (R² = 0.96, P < 0.001; intraclass correlation coefficient = 0.971), with 96% of ovulations occurring within ±1 day. The Mira PDG increase was also strongly associated with ultrasound-confirmed day of ovulation (R² = 0.87, P < 0.001). First-morning urine hormones were significantly associated with serum hormones when collected within 90 min (LH: R² = 0.92; E13G: R² = 0.73; R² = 0.61; R² = 0.75). Anovulatory cycles were identified in 11% of regularly cycling participants.
Quantitative urinary hormone monitoring with the Mira monitor provides accurate prediction and confirmation of ovulation, with strong urine-serum associations supporting reduced reliance on serial serum draws in select patients. These findings support clinical adoption of quantitative urinary fertility monitoring.
Balachandran S et al., 2026·Journal of obstetrics and gynaecology Canada : JOGC = Journal d'obstetrique et gynecologie du Canada : JOGC
To assess the impact of the COVID-19 pandemic on reproductive outcomes in patients with recurrent pregnancy loss (RPL) and the influence of material and social deprivation on these outcomes.
This retrospective cohort study included RPL patients seen at a specialized clinic between March 1, 2018, and February 28, 2022. Patients were categorized into two groups based on care period: pre-pandemic (March 1, 2018-February 29, 2020) and pandemic (March 1, 2020-February 28, 2022). Cumulative probabilities of birth were estimated using the cumulative incidence function within a competing risk framework, treating pregnancy loss as a competing event. Fine and Gray regression models calculated sub-distribution hazard ratio (sHR) of birth.
544 patients were included in the study, with 255 in the pre-pandemic group and 289 in the pandemic group. Individuals in the pandemic group were less likely to achieve pregnancy than those in the pre-pandemic group (relative risk = 0.50, 95% confidence interval [CI] 0.39 - 0.66). Among those who conceived, the cumulative probability of live birth was 0.77 in both groups. Relative to individuals residing in high-social deprivation neighborhoods, those living in moderately deprived areas had higher sub-distribution hazards of live birth (adjusted sHR = 1.97, 95% CI 1.25 - 3.10; P = 0.003).
Within specialized RPL care and a universal maternity care system, pregnancy rates were lower during the first two years of the COVID-19 pandemic. However, among those who conceived, the probability of achieving a live birth remained similar between the pre-pandemic and pandemic periods.
Bouchard TP et al., 2026·Reproductive biomedicine online·Free to read
Does formation of the corpus luteum help to identify the day of ovulation on ultrasound when follicular collapse is missed, and how reliable are sonographers versus a review panel in identifying the day of ovulation on ultrasound? Sonographers in a clinic in Canada performed serial endovaginal ultrasound scans (six to eight per cycle) to identify the day of ovulation in regularly cycling women (n = 40) who were followed for one to five cycles (n = 85). The day of ovulation was identified by: (i) identification of the dominant follicle; (ii) disappearance of the dominant follicle; and (iii) identification and dating of the corpus luteum. The main outcome measures were inter-rater reliability between two sonographers, and Bland-Altman agreement between the supervising sonographer and a panel that reviewed each scan to identify the day of ovulation. Of the 85 menstrual cycles reviewed, two cycles did not have sufficient data to date ovulation, one cycle showed an incidental dermoid cyst, and 11 cycles showed anovulatory patterns. This left a total of 71 cycles (84%) for which intra-rater reliability between two sonographers for identifying the day of ovulation was high (intraclass correlation coefficient = 0.99, P < 0.0001), and Bland-Altman agreement showed no significant difference in the estimated day of ovulation between the supervising sonographer and the panel (t = -0.28, P = 0.78). Corpus luteum criteria were necessary to help identify the day of ovulation in 14 of 71 cycles (20%). The estimated day of ovulation can be determined reliably on ultrasound by trained sonographers using collapse of the dominant follicle and formation of the corpus luteum based on six to eight scans per cycle.
Related research
Fertility and Outcomes · Conception After Excision
To evaluate the effect of endometriosis on pregnancy outcomes. Systematic review and meta-analysis. Not applicable. PATIENT(S): Women with or without endometriosis. INTERVENTION(S): Electronic databases searched from their inception until February 2017 with no limit for language and with all cohort studies reporting the incidence of obstetric complications in women with a diagnosis of endometriosis compared with a control group (women without a diagnosis of endometriosis) included. MEAN OUTCOME MEASURE(S): Primary outcome of incidence of preterm birth at <37 weeks with meta-analysis performed using the random effects model of DerSimonian and Laird to produce an odds ratio (OR) with 95% confidence interval (CI). RESULT(S): Twenty-four studies were analyzed comprising 1,924,114 women. In most of them, the diagnosis of endometriosis was made histologically after surgery. Women with endometriosis had a statistically significantly higher risk of preterm birth (OR 1.63; 95% CI, 1.32-2.01), miscarriage (OR 1.75; 95% CI, 1.29-2.37), placenta previa (OR 3.03; 95% CI, 1.50-6.13), small for gestational age (OR 1.27; 95% CI, 1.03-1.57), and cesarean delivery (OR 1.57; 95% CI, 1.39-1.78) compared with the healthy controls. No differences were found in the incidence of gestational hypertension and preeclampsia. CONCLUSION(S): Women with endometriosis have a statistically significantly higher risk of preterm birth, miscarriage, placenta previa, small for gestational age infants, and cesarean delivery.
Fertility and Outcomes · Conception After Excision
Minebois H et al., 2017·Gynécologie Obstétrique Fertilité & Sénologie
In spontaneous pregnancies, endometriosis appears to be a risk factor of miscarriage. The aim of this study is to evaluate the association between endometriosis and miscarriage in spontaneous pregnancy. We searched the Cochrane Library, Medline of eligible studies from inception to December 2016, without any restriction. We selected studies that compared endometriosis-affected pregnant women to disease-free pregnant women. To ensure the quality of the methodology, the PRISMA criteria have been met at all stages of the development of this meta-analysis. The primary adverse pregnancy outcomes studied was miscarriage. Three reviewers independently extracted the studies' characteristics and outcome data. Of 225 identified abstracts, 4 primary studies met our inclusion criteria by comparing spontaneous pregnant patients with endometriosis to disease-free women. Miscarriage rate was higher in the endometriosis group (OR 1.77 [CI 95% 1.13-2.78]). In spontaneous pregnancies, endometriosis appears to be a risk factor of miscarriages (almost 80% increased risk). Further prospective studies are needed to confirm these results in order to establish the exact impact of endometriosis on spontaneous pregnancy course.
Fertility and Outcomes · Conception After Excision
Schliep KC et al., 2022·Paediatr Perinat Epidemiol·Free full text on PubMed Central
Women with endometriosis may have an increased risk of adverse pregnancy outcomes. Research has focused on infertility clinic populations limiting generalisability. Few studies report differences by endometriosis severity. We investigated the relationships between endometriosis diagnosis, staging and typology and pregnancy outcomes among an operative and population-based sample of women. Menstruating women ages 18-44 years enrolled in the ENDO Study (2007-2009), including the operative cohort: 316 gravid women undergoing laparoscopy/laparotomy at surgical centres in Utah and California; and the population cohort: 76 gravid women from the surgical centres' geographic catchment areas. Pregnancy outcomes were ascertained by questionnaire and included all pregnancies prior to study enrolment. Endometriosis was diagnosed via surgical visualisation in the operative cohort and pelvic magnetic resonance imaging in the population cohort. Adjusted prevalence ratios (aPR) and 95% confidence intervals (CI) were estimated using generalised linear mixed models for pregnancy outcomes, adjusting for women's age at study enrolment and at pregnancy, surgical site, body mass index and lifestyle factors. Women in the operative cohort with visualised endometriosis (n = 109, 34%) had a lower prevalence of live births, aPR 0.94 (95% CI 0.85, 1.03) and a higher prevalence of miscarriages, aPR 1.48 (95% CI 1.23, 1.77) compared with women without endometriosis. The direction and magnitude of estimates were similar in the population cohort. Women with deep endometriosis were 2.98-fold more likely (95% CI 1.12, 7.95) to report a miscarriage compared with women without endometriosis after adjusting for women's age at study enrolment and at pregnancy, surgical site and body mass index. No differences were seen between endometriosis staging and pregnancy outcomes. While there was no difference in number of pregnancies among women with and without endometriosis in a population-based sample, pregnancy loss was more common among women with endometriosis, notably among those with deep endometriosis.
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.
Endometriosis › Fertility and Outcomes › Conception After Excision · Research Methods › Evidence Synthesis › Meta-Analysis
Paul J Yong, Samaa Matwani, Chantalle Brace, Andrea Quaiattini, Mohamed A Bedaiwy, Arianne Albert, Catherine Allaire
P Yong, S Matwani, C Brace, A Quaiattini, M Bedaiwy, A Albert, Cathy Allaire, Kate Allaire, C Allaire
PMID 31546066 31546066 DOI 10.1016/j.jmig.2019.09.778 10.1016/j.jmig.2019.09.778 Yong et al. 2020, Yong 2020
