Recurrent pregnancy loss and future risk of female malignancies

Pregnancy, abortion, and birth control methods' complicity with breast cancer occurrence

Reproductive factors play significantly important roles in determining the breast cancer (BC) risk. The impact of pregnancy, abortion, and birth control methods on tumor development remains unclear. It has been found that early full-term pregnancies in young women can lower their lifetime risk of developing the type of cancer in question. However, having a first full-term pregnancy at an older age can increase this risk. The relationship between pregnancy and breast cancer (BC) is, however, much more complicated. Both induced and spontaneous abortions lead to sudden changes in hormonal balance, which could cause different effects on sensitive breast epithelial cells, making abortion a potential risk factor for breast cancer. The influence of hormonal contraception on carcinogenesis is not comprehensively understood, and therefore, more exhaustive analysis of existing data and further investigation is needed. This review explores how the mentioned reproductive factors affect the risk of breast cancer (BC), focusing on the molecular mechanisms that contribute to its complexity. By comprehending this intricate network of relationships, we can develop new strategies for predicting and treating the disease.

Reproductive factors and subsequent pregnancy outcomes in patients with prior pregnancy loss

BACKGROUND

At present, individualized interventions can be given to patients with a clear etiology of pregnancy loss to improve the subsequent pregnancy outcomes, but the current reproductive status of the patient cannot be changed. The aim of this study was to investigate the association between female reproductive status and subsequence pregnancy outcome in patients with prior pregnancy loss (PL).

METHODS

A prospective, dynamic population cohort study was carried out at the Second Hospital of Lanzhou University. From September 2019 to February 2022, a total of 1955 women with at least one previous PL were enrolled. Maternal reproductive status and subsequent reproductive outcomes were recorded through an electronic medical record system and follow-up. Logistic regression was used to evaluate the association between reproductive status and the risk of subsequent reproductive outcomes.

RESULTS

Among all patients, the rates of subsequent infertility, early PL, late PL, and live birth were 20.82%, 24.33%, 1.69% and 50.77% respectively. In logistic regression, we found that age (OR 1.08, 95% CI 1.04-1.13) and previous cesarean delivery history (OR 2.46, 95% CI 1.27-4.76) were risk factors for subsequent infertility in patients with PL. Age (OR 1.06, 95% CI 1.03-1.10), age at first pregnancy (OR 1.06, 95% CI 1.03-1.10), BMI (OR 1.06, 95% CI 1.02-1.11), previous PL numbers (OR 1.18, 95% CI 1.04-1.57) and without pre-pregnancy intervention (OR 1.77, 95% CI 1.35-2.24) were risk factors for non-live birth. Age (OR 1.06, 95% CI 1.03-1.09), age at first pregnancy (OR 1.06, 95% CI 1.02-1.09), BMI (OR 1.07, 95% CI 1.02-1.11), previous PL numbers (OR 1.15, 95% CI 1.02-1.31) and without pre-pregnancy intervention (OR 2.16, 95% CI 1.65-2.84) were risk factors for PL.

CONCLUSIONS

The reproductive status of people with PL is strongly correlated with the outcome of subsequent pregnancies. Active pre-pregnancy intervention can improve the subsequent pregnancy outcome.

TRIAL REGISTRATION

This study was registered in the Chinese Clinical Trial Registry with the registration number of ChiCTR2000039414 (27/10/2020).

Fetal loss and long-term maternal morbidity and mortality: A systematic review and meta-analysis

BACKGROUND

Evidence suggests common pathways between pregnancy losses and subsequent long-term maternal morbidity, rendering pregnancy complications an early chronic disease marker. There is a plethora of studies exploring associations between miscarriage and stillbirth with long-term adverse maternal health; however, these data are inconclusive.

METHODS AND FINDINGS

We systematically searched MEDLINE, EMBASE, AMED, BNI, CINAHL, and the Cochrane Library with relevant keywords and MeSH terms from inception to June 2023 (no language restrictions). We included studies exploring associations between stillbirth or miscarriage and incidence of cardiovascular, malignancy, mental health, other morbidities, and all-cause mortality in women without previous pregnancy loss. Studies reporting short-term morbidity (within a year of loss), case reports, letters, and animal studies were excluded. Study selection and data extraction were performed by 2 independent reviewers. Risk of bias was assessed using the Newcastle Ottawa Scale (NOS) and publication bias with funnel plots. Subgroup analysis explored the effect of recurrent losses on adverse outcomes. Statistical analysis was performed using an inverse variance random effects model and results are reported as risk ratios (RRs) with 95% confidence intervals (CIs) and prediction intervals (PIs) by combining the most adjusted RR, odds ratios (ORs) and hazard ratios (HRs) under the rare outcome assumption. We included 56 observational studies, including 45 in meta-analysis. There were 1,119,815 women who experienced pregnancy loss of whom 951,258 had a miscarriage and 168,557 stillbirth, compared with 11,965,574 women without previous loss. Women with a history of stillbirth had a greater risk of ischaemic heart disease (IHD) RR 1.56, 95% CI [1.30, 1.88]; p < 0.001, 95% PI [0.49 to 5.15]), cerebrovascular (RR 1.71, 95% CI [1.44, 2.03], p < 0.001, 95% PI [1.92, 2.42]), and any circulatory/cardiovascular disease (RR 1.86, 95% CI [1.01, 3.45], p = 0.05, 95% PI [0.74, 4.10]) compared with women without pregnancy loss. There was no evidence of increased risk of cardiovascular disease (IHD: RR 1.11, 95% CI [0.98, 1.27], 95% PI [0.46, 2.76] or cerebrovascular: RR 1.01, 95% CI [0.85, 1.21]) in women experiencing a miscarriage. Only women with a previous stillbirth were more likely to develop type 2 diabetes mellitus (T2DM) (RR: 1.16, 95% CI [1.07 to 2.26]; p < 0.001, 95% PI [1.05, 1.35]). Women with a stillbirth history had an increased risk of developing renal morbidities (RR 1.97, 95% CI [1.51, 2.57], p < 0.001, 95% [1.06, 4.72]) compared with controls. Women with a history of stillbirth had lower risk of breast cancer (RR: 0.80, 95% CI [0.67, 0.96], p-0.02, 95% PI [0.72, 0.93]). There was no evidence of altered risk of other malignancies in women experiencing pregnancy loss compared to controls. There was no evidence of long-term mental illness risk in women with previous pregnancy losses (stillbirth: RR 1.90, 95% CI [0.93, 3.88], 95% PI [0.34, 9.51], miscarriage: RR 1.78, 95% CI [0.88, 3.63], 95% PI [1.13, 4.16]). The main limitations include the potential for confounding due to use of aggregated data with variable degrees of adjustment.

CONCLUSIONS

Our results suggest that women with a history of stillbirth have a greater risk of future cardiovascular disease, T2DM, and renal morbidities. Women experiencing miscarriages, single or multiple, do not seem to have an altered risk.

Future risk of metabolic syndrome after recurrent pregnancy loss: a cohort study using UK Biobank

OBJECTIVE

To evaluate the risk of metabolic syndrome (MS) after recurrent pregnancy loss (RPL) using UK Biobank data. A history of pregnancy loss is associated with the development of cardiovascular diseases in the future. However, the association between RPL and subsequent MS is poorly understood. Therefore, we aimed to check the risk of MS after RPL.

DESIGN

The study population was divided into 2 groups according to reproductive history: women with a history of RPL and women without a history of RPL. Recurrent pregnancy loss was defined as 2 or more spontaneous miscarriages, and MS was defined as at least 3 of the following: abdominal obesity, hypertriglyceridemia, low high-density lipoprotein cholesterol levels, high-blood pressure, and hyperglycemia.

SETTING

UK Biobank resource.

PATIENTS

The UK Biobank is a prospective cohort study that enrolled individuals aged between 40 and 69 years whose medical and reproductive histories were retrieved at enrollment. In this cohort, only women with a history of at least one pregnancy were selected.

INTERVENTIONS

Recurrent pregnancy loss.

MAIN OUTCOME MEASURES

The primary outcome was the prevalence of MS. The secondary outcomes were 5 diagnostic components of MS.

RESULTS

We analyzed 228,674 women, including 15,702 with a history of RPL and 212,972 without a history of RPL. Women with a history of RPL have a higher prevalence of MS between the ages of 40 and 60 years (33.0% vs. 31.5%). After adjusting for covariates (age, race, number of live births, early menopause, smoking, alcohol consumption, and physical activity), the increased risk of MS after RPL remained significant (adjusted odds ratio, 1.10; 95% confidence interval, 1.06-1.15). Furthermore, in the analysis of the 5 diagnostic components of MS, a history of RPL significantly increased the risk of abdominal obesity, hypertriglyceridemia, low high-density lipoprotein cholesterol levels, and hyperglycemia.

CONCLUSION

Middle-aged women with a history of RPL have an increased risk of MS.

Reproduction as a window to future health in women

Cultivating awareness for reproduction as a window to future health presents an opportunity for early identification and modification of risk factors that can affect both individual and population-level morbidity and mortality. Infertility could serve as both a window into future health as well as a pathway to future pathology. The underlying mechanisms of infertility may share common pathways with long-term risk for health and well-being. Making this identification early in the disease process may improve opportunities for intervention, and deepen our understanding of long-term risk. Additionally, fertility treatments may increase individual risk. Only by making these associations and designing studies to understand how disease and treatment risk impact health can we truly fulfill our goal of building healthy families. The aim of this review is to discuss the short-term impact of fertility challenges and treatment, long-term associations of infertility with morbidity and mortality, and the role of parity in modifying these risk associations.

Perinatal outcomes in nulliparous women with a history of multiple pregnancy losses according to number of previous pregnancy losses

BACKGROUND

While it is widely acknowledged that pregnancy losses can lead to negative outcomes for both mothers and fetuses, there is limited information available on the specific levels of risk associated with each additional pregnancy loss.

OBJECTIVE

This study aimed to investigate the effect of number of previous pregnancy losses among nulliparous women on maternal and neonatal adverse outcomes.

STUDY DESIGN

This was a multicenter retrospective cohort study. The study population included all nulliparous women with singleton pregnancies who delivered in all university-affiliated obstetrical centers in a single geographic area between 2003 and 2021. Maternal and neonatal outcomes of women who delivered at our medical centers and had varying numbers of previous pregnancy losses were compared with women who had no previous pregnancy loss. The primary outcome of this study was preterm delivery rate at <37 weeks of gestation. The secondary outcomes were adverse maternal and neonatal outcomes. Univariate analysis was performed using multiple logistic regression modeling.

RESULTS

During the study period, 97,904 nulliparous women met the inclusion and exclusion criteria. Of those women, 84,245 (86%) had no previous pregnancy losses (reference group), 10,724 (11%) had 1 previous pregnancy loss, 2150 (2.2%) had 2 previous pregnancy losses, 516 (0.5%) had 3 previous pregnancy losses, 160 (0.2%) had 4 previous pregnancy losses, and 99 (0.1%) had ≥5 previous pregnancy losses. Women who had previous pregnancy losses had significantly higher rates of preterm delivery, hypertensive disorders of pregnancy, diabetes mellitus (pregestational and gestational), unplanned cesarean delivery, perinatal death, neonatal intensive care unit admissions, and neonatal hypoglycemia. The risks of preterm delivery and most other adverse obstetrical outcomes correlated with the number of previous pregnancy losses. Multivariate analyses showed that each previous pregnancy loss was associated with an additional, significant, increased risk of preterm delivery of 14% at <37 weeks of gestation, 37% at <34 weeks of gestation, 45% at <32 weeks of gestation, and 77% at <28 weeks of gestation.

CONCLUSION

A history of previous pregnancy losses increased the risk of preterm delivery and other perinatal outcomes in a dose-dependent manner. To minimize perinatal complications, obstetricians should be aware of the risks and complications in this unique population, consider close monitoring of the cervical length, and maintain high vigilance in case of complications with special attention to other potentially modifiable risks.

Cancer diagnosis among women with recurrent pregnancy loss: a retrospective cohort study

RESEARCH QUESTION

What is relationship between unexplained recurrent pregnancy loss (RPL) and risk of cancer morbidity?

DESIGN

A retrospective observational cohort study was conducted, based on data from a tertiary medical centre. RPL cases (exposed) were defined as women presenting with three or more unexplained confirmed pregnancy losses at 5-24 weeks, whose first visit to the RPL clinic was between 1990 and 2010. The unexposed group included women giving birth who were not RPL patients; these were matched by age and year of giving birth/admission (1:5 ratio). Data from the RPL and the live birth registries were cross-linked to the Israeli national cancer registry according to the unique ID number and merged into one database.

RESULTS

The study group comprised 937 RPL patients who were matched by maternal age (P = 1.0) and admission date (P = 0.84) to 4685 women achieving a live birth. There was no difference in overall cancer incidence between groups (adjusted odds ratio [OR] 0.76, 95% confidence interval [CI] 0.55-1.03; P = 0.08). The secondary RPL group showed a trend towards decreased cancer morbidity incidence compared with primary RPL (adjusted OR 0.65, 95% CI 0.41-1.03; P = 0.07). Analysis by cancer type showed a similar risk for breast cancer among women with RPL compared with live birth, but a significantly lower risk for gynaecological cancers among women with RPL (adjusted OR 0.25, 95% CI 0.08-0.79; P = 0.018).

CONCLUSIONS

Unexplained RPL may be related to a lower risk of gynaecological cancers, possibly explained by hyper-responsive immunological mechanisms involving uterine natural killer cells.

Maternal Smoking during Pregnancy and the Risk for Childhood Infectious Diseases in the Offspring: A Population-Based Cohort Study

OBJECTIVE

Infectious diseases account for up to 43% of childhood hospitalizations. Given the magnitude of infection-related hospitalizations, we aimed to evaluate the effect of maternal smoking during pregnancy on the risk for long-term childhood infectious morbidity.

STUDY DESIGN

This is a population-based cohort analysis comparing the long-term risk for infectious diseases, in children born to mothers who smoked during pregnancy versus those who did not. Infectious diseases were predefined based on International Classification of Diseases, Ninth Revision codes. Deliveries occurred between the years 1991 and 2014.

RESULTS

A total of 246,854 newborns met the inclusion criteria; 2,986 (1.2%) were born to mothers who smoked during pregnancy. Offspring of smokers had significantly higher risk for several infectious diseases during childhood (upper respiratory tract, otitis, viral infections, and bronchitis) as well as increased risk for total infection-related hospitalizations (odds ratio = 1.5, 95% confidence interval [CI]: 1.3-1.7; p = 0.001). Cumulative incidence of infection-related hospitalizations was significantly higher in offspring of smokers (log-rank test, p = 0.001). Controlling for maternal age, diabetes, hypertensive disorders, and gestational age at index delivery, smoking remained an independent risk factor for infectious diseases during childhood (adjusted hazard ratio = 1.5, 95% CI: 1.3-1.6; p = 0.001).

CONCLUSION

Intrauterine exposure to maternal smoking may create an environment leading to an increased future risk for long-term pediatric infectious morbidity of the offspring.

Recurrent pregnancy loss

Recurrent pregnancy loss is a distressing pregnancy disorder experienced by ~2.5% of women trying to conceive. Recurrent pregnancy loss is defined as the failure of two or more clinically recognized pregnancies before 20-24 weeks of gestation and includes embryonic and fetal losses. The diagnosis of an early pregnancy loss is relatively straightforward, although progress in predicting and preventing recurrent pregnancy loss has been hampered by a lack of standardized definitions, the uncertainties surrounding the pathogenesis and the highly variable clinical presentation. The prognosis for couples with recurrent pregnancy loss is generally good, although the likelihood of a successful pregnancy depends on maternal age and the number of previous losses. Recurrent pregnancy loss can be caused by chromosomal errors, anatomical uterine defects, autoimmune disorders and endometrial dysfunction. Available treatments target the putative risk factors of pregnancy loss, although the effectiveness of many medical interventions is controversial. Regardless of the underlying aetiology, couples require accurate information on their chances of having a baby and appropriate support should be offered to reduce the psychological burden associated with multiple miscarriages. Future research must investigate the pathogenesis of recurrent pregnancy loss and evaluate novel diagnostic tests and treatments in adequately powered clinical trials.

Cytokine imbalance at materno-embryonic interface as a potential immune mechanism for recurrent pregnancy loss

Recurrent pregnancy loss (RPL) is a prominent reproductive disease that distresses about 2%-5% of couples. RPL is the loss of two or more successive spontaneous pregnancies prior to the 20th week of embryo development. The commencement of pregnancy necessitates implantation of the embryo into responsive maternal decidua synchronized with the process of placentation, decidual and myometrial trophoblast incursion as well as refashioning of spiral blood arteries of uterus. The collapse of any of the processes fundamental for pregnancy success may result into an array of pregnancy problems including spontaneous pregnancy loss. Endometrium of human female manufactures an extensive range of cytokines during the proliferative and secretory stage of the menstrual cycle. These endometrial cytokines are thought as major players for making the uterus ready for embryo implantation and placental development during pregnancy. Decidual cytokines regulate the invasion of trophoblast and remodeling of spiral arteries as well as take part in immune suppression to accomplish the pregnancy. Deterrence of maternal rejection of embryo needs a regulated milieu, which takes place essentially at the embryo-maternal interface and the tissues of the uterus. The reasons of RPL remain anonymous in a large number of cases that lead to difficulties in management and severe trauma in couples. Cytokine modulatory therapies have been shown promising for preventing RPL. Further study of novel factors is wanted to establish more effective RPL treatment protocols. The present study aims to review the outcome of cytokine breach at materno-embryonic interface and the efficacy of cytokine modulatory therapies in RPL.

Maternal history of recurrent pregnancy loss and future risk of ophthalmic morbidity in the offspring

OBJECTIVE

The objective of the study was to investigate whether maternal history of recurrent pregnancy loss (RPL) is associated with offspring childhood ophthalmic morbidity.

METHOD

A hospital-based cohort analysis comparing long-term offspring ophthalmic morbidity in women with and without a history of RPL was performed. Ophthalmic morbidity included hospitalizations involving a pre-defined set of ICD-9 codes. Offspring with congenital anomalies, perinatal mortality cases, and multifetal pregnancies were excluded from the analysis. Cumulative morbidity incidence was compared using Kaplan-Meier survival curves, and the risk of long-term ophthalmic morbidity was assessed by Cox proportional hazards model after adjustment for confounders.

RESULTS

During the study period, 242,187 newborns met the inclusion criteria; 5% (12,182) of them were offspring born to mothers with a history of RPL. Ophthalmic morbidity was significantly more common in the RPL group (1.3% vs 0.9%, p < .001, Kaplan-Meier log-rank p < .001). Adjustment for confounders, such as maternal age, gestational age, hypertensive disorders, and maternal diabetes, using Cox regression found that being born to a mother with RPL was independently associated with long-term ophthalmic morbidity (adjusted HR 1.35, 95% CI 1.15-1.59, p < .001).

CONCLUSION

Being born to a mother with RPL is independently associated with an increased risk of ophthalmic morbidity.

Tubal ligation during cesarean delivery and future risk for ovarian cancer: a population-based cohort study

OBJECTIVE

Data regarding the effect of post-partum bilateral tubal ligation (BTL) on future risk for ovarian cancer (OC) is lacking. In the current study, we aimed to evaluate the effect of BTL during cesarean delivery (CD) on the long-term risk for OC.

STUDY DESIGN

A population-based cohort analysis of women above the age of 35 that underwent CD in their last delivery, comparing the long-term risk for OC between patients that had a Pomeroy excisional BTL and those that did not. OC diagnosis was pre-defined based on ICD-9 codes. Procedures occurred between the years 1991-2017. Kaplan-Meier survival curve was used to compare the cumulative incidence of OC over time and Cox proportional hazards model was constructed to control for confounders.

RESULTS

During the study period 13,124 women met the inclusion criteria; 9438 (71.9%) of which had only CD and 3686 (28.1%) underwent CD with BTL. Despite the significantly higher incidence of maternal factors that might increase the long-term risk for OC in the BTL group (advanced maternal age, obesity, hypertensive diseases during pregnancy and diabetes mellitus), the cumulative incidence of OC cases was not significantly different between the two groups (Log-rank test p = 0.199). Likewise, when performing a Cox regression model controlling for maternal age, obesity, hypertensive diseases and diabetes, OC risk was not significantly different between the groups (adjusted HR 2.36, 95% CI 0.73-7.62; p = 0.149).

CONCLUSION

Despite an increased incidence of known risk factors for OC, patients that underwent BTL during CD did not have increased long-term risk for OC.

Phenome-Wide Analysis of Short- and Long-Run Disease Incidence Following Recurrent Pregnancy Loss Using Data From a 39-Year Period

Background It is unclear how recurrent pregnancy loss (RPL) impacts disease risk and whether there is a difference in risk between women with or without a live birth before RPL (primary versus secondary RPL). We investigated the disease risk following RPL, and whether there was a difference between primary and secondary RPL. Methods and Results Using population-wide healthcare registries from Denmark, we identified a cohort of 1 370 896 ever-pregnant women aged 12 to 40 years between 1977 and 2016. Of this cohort, 10 691 (0.77%) fulfilled the criteria for RPL (50.0% primary RPL). Average follow-up was 15.8 years. Incidence rate ratios were calculated in a phenome-wide manner. Diagnoses related to assessment and diagnosis of RPL and those appearing later in life were separated using a mixture model. Primary RPL increased the risk of subsequent cardiovascular disorders, including atherosclerosis, cerebral infarction, heart failure, and pulmonary embolism, as well as systemic lupus erythematosus, chronic obstructive pulmonary disease, anxiety, and obsessive-compulsive disorder. Women with secondary RPL had no increased risk of cardiovascular disorders. However, we observed an increased risk of gastrointestinal disorders such as irritable bowel syndrome and intestinal malabsorption, as well as mental disorders and obstetric complications. Conclusions RPL is a risk factor for a spectrum of disorders, which is different for primary and secondary RPL. Screening following RPL explains some associations, but the remaining findings suggest that RPL influences or shares cause with cardiovascular disorders, autoimmune disorders, and mental disorders. Research into the pathophysiology of RPL and later diseases merits further investigation.

Increased incidence of cancer in the follow-up of obstetric antiphospholipid syndrome within the NOH-APS cohort

Malignancies can be associated with positive antiphospholipid antibodies but the incidence of cancer among women with the purely obstetric form of antiphospholipid syndrome (APS) is currently unknown. Our aim was to investigate the comparative incidence of cancers in women with a history of obstetric APS within a referral university hospital-based cohort (NOH-APS cohort). We performed a 17-year observational study of 1,592 non-thrombotic women with three consecutive spontaneous abortions before the 10^th week of gestation or one fetal death at or beyond the 10^th week of gestation. We compared the incidence of cancer diagnosis during follow-up among the cohort of women positive for antiphospholipid antibodies (n=517), the cohort of women carrying the F5 rs6025 or F2 rs1799963 polymorphism (n=279) and a cohort of women with negative thrombophilia screening results (n=796). The annualized rate of cancer was 0.300% (0.20%-0.44%) for women with obstetric APS and their cancer risk was substantially higher than that of women with negative thrombophilia screening [adjusted hazard ratio (aHR) 2.483; 95% confidence interval (CI) 1.27-4.85]. The computed standardized incidence ratio for women with obstetric APS was 2.89; 95% CI: 1.89-4.23. Among antiphospholipid antibodies, lupus anticoagulant was associated with incident cancers (aHR 2.608; 95% CI: 1.091-6.236). Our cohort study shows that the risk of cancer is substantially higher in women with a history of obstetric APS than in the general population, and in women with a similar initial clinical history but negative for antiphospholipid antibodies.

Thyroid Peroxidase Antibodies and Prospective Live Birth Rate: A Cohort Study of Women with Recurrent Pregnancy Loss

Background: Thyroid autoimmunity has been associated with pregnancy loss. Suggested mechanisms include thyroid function aberrations or an underlying breach of immunotolerance. We hypothesized that thyroid autoimmunity is a marker of the latter in women with recurrent pregnancy loss. This study investigated thyroid peroxidase antibody (TPOAb) status as a predictor of live birth in women with unexplained recurrent pregnancy loss. Methods: Cohort study of 825 consecutive women with recurrent pregnancy loss followed at the tertiary referral center for Recurrent Pregnancy Loss, Copenhagen University Hospital (Rigshospitalet), from 2011 to 2017. Recurrent pregnancy loss was defined as ≥3 consecutive losses, and as unexplained by absence of antiphospholipid syndrome, parental chromosome abnormality, or uterus malformation. Upon first visit, all women were screened for thyrotropin (TSH) and TPOAbs (TPOAb positivity: ≥60 kIU/L). Adjusted logistic regression analyses included as covariates the following: maternal age, TSH, previous number of losses, body mass index, smoking, pregnancy achieved by assisted reproductive technology, and thyroxine replacement (T4) treatment. Results: We included 825 women with a total of 3246 previous losses, of whom 139 (16.8%) were TPOAb positive. TPOAb positivity was not associated with the previous number of losses (p = 0.41). Women with unexplained recurrent pregnancy loss had a live birth rate in the first pregnancy after referral of 62.8% (285 of 454). TPOAb positivity was found in 78 of 454 (17.2%) women and was associated with a reduced live birth rate (51.3% vs. 65.2%, p = 0.02, adjusted odds ratio [aOR] 0.2 [0.1-0.6] p = 0.001). Treatment with T4 increased live birth rate significantly (aOR 3.7 [1.4-9.8], p = 0.007), and TPOAb-positive women receiving T4 had a live birth rate similar to that of TPOAb-negative women not receiving T4 (p = 0.70). Only 30% of TPOAb-positive women and 39% of women treated with T4 during pregnancy had known thyroid disease at referral. Conclusion: In a large cohort of women with unexplained recurrent pregnancy loss, TPOAb positivity was predictive of a reduced live birth rate. However, T4 treatment improved odds of live birth. The study supports screening for TPOAbs as a risk factor in women with unexplained recurrent pregnancy loss. The beneficial effect of T4 treatment in this high-risk group needs confirmation by randomized controlled trials. Close collaboration between fertility experts and endocrinologists is paramount.

Pregnancy Loss and Cancer Risk: A Nationwide Observational Study

BACKGROUND

Cancer is the second leading cause of death worldwide. Few studies have investigated if recurrent pregnancy loss is associated with an increased risk of cancer. We aimed to assess whether pregnancy loss is associated with later cancer development.

METHODS

We identified all invasive cancers after age 40, among all Danish women born between January 1957 and December 1972, ensuring a full reproductive history. Cases were matched by birth year 1:10 to cancer-free controls. Women were followed until the end of 2017. The number of pregnancy losses (miscarriages or still births) was correlated to long-term cancer risk using conditional logistic regression, providing odds ratios for specific cancers with different numbers of pregnancy losses, all adjusted for age, education, and other potential confounders.

FINDINGS

The study included 28,785 women with cancer (mean age 48.7 [SD 5.0]) and 283,294 matched controls (mean age 48.6 [SD 5.0]). We found no overall association between pregnancy loss and later development of 11 site-specific types of cancer or cancer overall. Taking the sequence of pregnancy losses into account, primary recurrent pregnancy loss (three consecutive pregnancy losses without prior live birth) was associated with later overall cancer by an odds ratio of 1.27 (1.04-1.56). Secondary recurrent pregnancy loss showed no association to cancer.

INTERPRETATION

Pregnancy loss was not associated with later cancer development. Women with primary recurrent pregnancy loss had a borderline significant association to later cancer overall, this may be a chance finding.

FUNDING

Ole Kirk's Foundation and Copenhagen University Hospital Rigshospitalet's Research Grant.