Breast feeding, other reproductive factors and rheumatoid arthritis. A prospective study

Dual role of pregnancy in breast cancer risk

Reproductive history is one of the strongest risk factors for breast cancer in women. Pregnancy can promote short-term breast cancer risk, but also reduce a woman's lifetime risk of breast cancer. Changes in hormone levels before and after pregnancy are one of the key factors in breast cancer risk. This article summarizes the changes in hormone levels before and after pregnancy, and the roles of hormones in mammary gland development and breast cancer progression. Other factors, such as changes in breast morphology and mammary gland differentiation, changes in the proportion of mammary stem cells (MaSCs), changes in the immune and inflammatory environment, and changes in lactation before and after pregnancy, also play key roles in the occurrence and development of breast cancer. This review discusses the dual effects and the potential mechanisms of pregnancy on breast cancer risk from the above aspects, which is helpful to understand the complexity of female breast cancer occurrence.

Etiology and Pathogenesis of Rheumatoid Arthritis-Interstitial Lung Disease

Interstitial lung disease (ILD) is one of the most serious extra-articular complications of rheumatoid arthritis (RA), which increases the mortality of RA. Because the pathogenesis of RA-ILD remains poorly understood, appropriate therapeutic strategies and biomarkers have not yet been identified. Thus, the goal of this review was to summarize and analyze the reported data on the etiology and pathogenesis of RA-ILD. The incidence of RA-ILD increases with age, and is also generally higher in men than in women and in patients with specific genetic variations and ethnicity. Lifestyle factors associated with an increased risk of RA-ILD include smoking and exposure to pollutants. The presence of an anti-cyclic citrullinated peptide antibody, high RA disease activity, and rheumatoid factor positivity also increase the risk of RA-ILD. We also explored the roles of biological processes (e.g., fibroblast-myofibroblast transition, epithelial-mesenchymal transition, and immunological processes), signaling pathways (e.g., JAK/STAT and PI3K/Akt), and the histopathology of RA involved in RA-ILD pathogenesis based on published preclinical and clinical models of RA-ILD in animal and human studies.

Menopausal factors and risk of seropositive rheumatoid arthritis in postmenopausal women: a nationwide cohort study of 1.36 million women

In previous literature regarding development of rheumatoid arthritis (RA), female reproductive factors have been described as protective factors, risk factors, or irrelevant, leading to inconsistent results. The aim of this study was to investigate the effect of female reproductive factors on the incidence of seropositive RA. A large population-based retrospective cohort of the National Health Insurance Service data in South Korea was used. Postmenopausal women who participated in both cardiovascular and breast cancer screening in 2009 were included and followed until date of seropositive RA diagnosis, death, or December 31, 2018. Multivariable-adjusted Cox proportional hazards model was used to assess the association between reproductive factors and incident seropositive RA. Of 1,357,736 postmenopausal women, 6056 women were diagnosed with seropositive RA, and the incidence rate was 54.16 cases/100,000 person-years. Reproductive factors other than hormone replacement therapy (HRT) were not significantly associated with seropositive RA incidence. Postmenopausal women who used HRT ≥ 5 years were associated with a higher aHR of incident seropositive RA than never-users (aHR 1.25; 95% CI 1.09–1.44). Alcohol consumption less than 30 g per day (aHR 0.80; 95% CI 0.74–0.87), regular physical activity (aHR 0.90; 95% CI 0.84–0.97), diabetes mellitus (aHR 0.85; 95% CI 0.78–0.93), and cancer (aHR 0.77; 95% CI 0.64–0.92) were associated with lower risk of seropositive RA. Most female reproductive factors did not significantly affect the development of seropositive RA in postmenopausal women. Only HRT is associated with a small but significant increase in risk of seropositive RA.

The importance of differences; On environment and its interactions with genes and immunity in the causation of rheumatoid arthritis

The current review uses rheumatoid arthritis (RA) as a prominent example for how studies on the interplay between environmental and genetic factors in defined subsets of a disease can be used to formulate aetiological hypotheses that subsequently can be tested for causality using molecular and functional studies. Major discussed findings are that exposures to airways from many different noxious agents including cigarette smoke, silica dust and more interact with major susceptibility genes, mainly HLA-DR genetic variants in triggering antigen-specific immune reactions specific for RA. We also discuss how several other environmental and lifestyle factors, including microbial, neural and metabolic factors, can influence risk for RA in ways that are different in different subsets of RA.The description of these processes in RA provides the best example so far in any immune-mediated disease of how triggering of immunity at one anatomical site in the context of known environmental and genetic factors subsequently can lead to symptoms that precede the classical inflammatory disease symptoms and later contribute also to the classical RA joint inflammation. The findings referred to in the review have led to a change of paradigms for very early therapy and prevention of RA and to efforts towards what we have named 'personalized prevention'. We believe that the progress described here for RA will be of relevance for research and practice also in other immune-mediated diseases.

Pregnancy and autoimmune diseases

Autoimmune diseases (AID) are more prevalent in women than in men, and pregnancy-related factors such as hormonal modulation and fetal microchimerism may influence the future risk of maternal AID. For women with AID, optimizing reproductive health requires a continuum of multidisciplinary care that initiates well before the desire for pregnancy is articulated. Family planning is essential so that pregnancy can be timed when disease is stable and to allow for appropriate medication adjustments. When contraception is used, the choice of method needs to take into consideration underlying disease and laboratory features. For females undergoing gonadotoxic therapy, options for preserving ovarian health and fertility warrant consideration, even among those who are not contemplating future pregnancy. Both maternal and fetal outcomes are optimized with multispecialty care as well as close monitoring during pregnancy and the postpartum period and when treatment regimens compatible with pregnancy are maintained to control underlying disease activity.

Pregnancy and rheumatoid arthritis

Rheumatoid arthritis commonly affects women of childbearing age. Fertility, family planning, control of disease activity and birth outcomes are all important issues to be discussed at preconception counseling. New data has offered insight on trends of fertility, disease control during pregnancy, and birth outcomes. This chapter provides an updated overview on expected disease course and management issues at each juncture with a particular focus on maintenance of tight disease control.

The association between gravidity, parity and the risk of developing rheumatoid arthritis: A systematic review and meta-analysis

OBJECTIVE

To establish if gravidity and parity associate with the development of rheumatoid arthritis (RA), and to establish if this effect is influenced by the time elapsed since pregnancy/childbirth, the number of pregnancies/childbirths, and serological status, through systematically reviewing the literature and undertaking a meta-analysis.

METHODS

We searched Medline/EMBASE (from 1946 to 2018) using the terms "rheumatoid arthritis.mp" or "arthritis, rheumatoid/" and "pregnancy.mp" or "pregnancy/" or "parity.mp" or "parity/" or "gravidity.mp" or "gravidity/" (observational study filter applied). Case-control/cohort studies that examined the relationship between parity/gravidity and the risk of RA in women were included. Studies reporting effect size data for RA in ever vs. never parous/gravid women as ORs/RRs with 95% confidence intervals were included in a meta-analysis. Other relationships (i.e. risk by pregnancy/childbirth numbers) were analysed descriptively.

RESULTS

Twenty studies (from 626 articles) met our inclusion criteria, comprising 14 case-control (4799 cases; 11,941 controls) and 6 cohort studies (8575 cases; 2,368,439 individuals). No significant association was observed in the meta-analysis of studies reporting the risk of RA in ever vs. never parous women (OR 0.91; 95% CI 0.80-1.04) and ever vs. never gravid women (OR 0.86; 95% CI 0.46-1.62). No consistent evidence of a relationship between the number of pregnancies/childbirths and RA risk was seen. No significant association was observed between being pregnant, or in the immediate post-partum period, and the risk of developing RA.

CONCLUSION

Our systematic review does not support the concept that gravidity and parity are associated with the risk of RA development.

Autoimmune Disease in Women: Endocrine Transition and Risk Across the Lifespan

Women have a higher incidence and prevalence of autoimmune diseases than men, and 85% or more patients of multiple autoimmune diseases are female. Women undergo sweeping endocrinological changes at least twice during their lifetime, puberty and menopause, with many women undergoing an additional transition: pregnancy, which may or may not be accompanied by breastfeeding. These endocrinological transitions exert significant effects on the immune system due to interactions between the hormonal milieu, innate, and adaptive immune systems as well as pro- and anti-inflammatory cytokines, and thereby modulate the susceptibility of women to autoimmune diseases. Conversely, pre-existing autoimmune diseases themselves impact endocrine transitions. Concentration-dependent effects of estrogen on the immune system; the role of progesterone, androgens, leptin, oxytocin, and prolactin; and the interplay between Th1 and Th2 immune responses together maintain a delicate balance between host defense, immunological tolerance and autoimmunity. In this review, multiple autoimmune diseases have been analyzed in the context of each of the three endocrinological transitions in women. We provide evidence from human epidemiological data and animal studies that endocrine transitions exert profound impact on the development of autoimmune diseases in women through complex mechanisms. Greater understanding of endocrine transitions and their role in autoimmune diseases could aid in prediction, prevention, and cures of these debilitating diseases in women.

Insight into the Endocrine System and the Immune System: A Review of the Inflammatory Role of Prolactin in Rheumatoid Arthritis and Psoriatic Arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that affects females three times more frequently than males. A potential role for hormones, such as prolactin (PRL), may in part explain this phenomenon. The risk of developing RA is increased in women who are lactating after the first pregnancy, which might be related to breastfeeding and the release of PRL. Other studies found a protective effect of PRL on RA development. Some studies have reported that hyperprolactinemia is more common in RA and serum PRL levels are correlated with several disease parameters, although others could not confirm these findings. Overall the plasma PRL levels are on average not elevated in RA. Previously, a small number of open-label clinical trials using bromocriptine, which indirectly decreases PRL levels, were performed in RA patients and showed clinical benefit, although others found the opposite effect. Locally produced PRL at the site of inflammation may have a crucial role in RA as well, as it has been shown that PRL can be produced by synovial macrophages. Locally produced PRL has both pro-inflammatory and anti-inflammatory effects in arthritis. Psoriatic arthritis (PsA) is also an autoinflammatory disease, in which the prolactin receptor is also expressed in macrophages. The aim of this review is to provide an overview of the potential role of PRL signaling in inflammatory joint diseases (RA and PsA) and its potential as a therapeutic target.

Number of parity and the risk of rheumatoid arthritis in women: A dose-response meta-analysis of observational studies

AIM

The association between parity and rheumatoid arthritis (RA) risk has been investigated, but results are controversial. Thus, our aim was to systematically analyze the effect of number of parity on the risk of RA in women.

METHODS

Relevant published studies were identified using PubMed and embase databases through 1 April 2016. We pooled the relative risks (RR) and 95% confidence intervals (CI) using random-effects models.

RESULTS

In all, 12 studies with a total of 2 497 580 participants and 11 521 RA cases were included. A borderline significant inverse association was observed when we compared parity with nulliparity for RA, with summarized RR = 0.90 (95%CI: 0.79-1.02; I²  = 58.5%, P_{heterogeneity}  = 0.010). In dose-response analysis, we observed a significant nonlinear (P_nonlinearity  = 0.000) relation between parity number and the risk of RA. Compared with null parity, the pooled RR of RA were 0.89 (95%CI: 0.86-0.93), 0.84 (95%CI: 0.79-0.89), 0.85 (95%CI: 0.79-0.90), 0.88 (95%CI: 0.81-0.95), 0.90 (95%CI: 0.83-0.97), 0.92 (95%CI: 0.84-1.02), and 0.94 (95%CI: 0.83-1.07) for 1, 2, 3, 4, 5, 6, and 7 live births, respectively. Subgroup and sensitivity analyses showed similar associations. No publication bias was found.

CONCLUSION

The findings from the current meta-analysis indicate that parity was related to decreased risk of RA. The greatest risk reduction appeared when the parity number reached two. Further studies are warranted to confirm our findings.

The role of the prolactin/vasoinhibin axis in rheumatoid arthritis: an integrative overview

Rheumatoid arthritis (RA) is a chronic, autoimmune, inflammatory disease destroying articular cartilage and bone. The female preponderance and the influence of reproductive states in RA have long linked this disease to sexually dimorphic, reproductive hormones such as prolactin (PRL). PRL has immune-enhancing properties and increases in the circulation of some patients with RA. However, PRL also suppresses the immune system, stimulates the formation and survival of joint tissues, acquires antiangiogenic properties upon its cleavage to vasoinhibins, and protects against joint destruction and inflammation in the adjuvant-induced model of RA. This review addresses risk factors for RA linked to PRL, the effects of PRL and vasoinhibins on joint tissues, blood vessels, and immune cells, and the clinical and experimental data associating PRL with RA. This information provides important insights into the pathophysiology of RA and highlights protective actions of the PRL/vasoinhibin axis that could lead to therapeutic benefits.

Pregnancy and autoimmune connective tissue diseases

Autoimmune connective tissue diseases predominantly affect women and often occur during the reproductive years. Thus, specialized issues in pregnancy planning and management are commonly encountered in this patient population. This chapter provides a current overview of pregnancy as a risk factor for onset of autoimmune disease, considerations related to the course of pregnancy in several autoimmune connective tissue diseases, and disease management and medication issues before pregnancy, during pregnancy, and in the postpartum period. A major theme that has emerged across these inflammatory diseases is that active maternal disease during pregnancy is associated with adverse pregnancy outcomes, and that maternal and fetal health can be optimized when conception is planned during times of inactive disease and through maintaining treatment regimens compatible with pregnancy.

Gluten Introduction, Breastfeeding, and Celiac Disease: Back to the Drawing Board

This commentary by the leadership of the North American Society for the Study of Celiac Disease (NASSCD) concerns recent research findings regarding infant feeding practices. Celiac disease has increased markedly in recent decades, and seroprevalence studies indicate that this is a true rise, rather than one due to increased awareness and testing. Prior studies have suggested that infant feeding practices and timing of initial gluten exposure are central to the development of celiac disease. Two recent multicenter randomized trials tested strategies of early or delayed gluten introduction in infants, and neither strategy appeared to influence celiac disease risk. These studies also found that breastfeeding did not protect against the development of celiac disease. While disappointing, these results should spur the study of wider environmental risk factors beyond infant feeding, such as intrauterine and perinatal exposures as well as environmental influences later in life, including drug exposure, microbial infections, and the microbiome. Given that celiac disease can develop at any age, it is imperative to study these proposed triggers so as to elucidate the loss of tolerance to gluten and to develop future intervention strategies.

Determinants of trends in breast-feeding indicators in Nigeria, 1999-2013

OBJECTIVE

The present study aimed to examine the trends and differentials in key breast-feeding indicators in Nigeria for the period 1999-2013.

DESIGN

Longitudinal study of trends (1999-2013) in optimal feeding practices using a series of population-based Nigerian Demographic and Health Surveys. Trends in socio-economic, health service and individual characteristics associated with key breast-feeding indicators were examined using multilevel regression analyses.

SETTING

Nigeria.

SUBJECTS

Children (n 88 152) aged under 24 months (n 8199 in 1999; n 7620 in 2003; n 33 385 in 2008; n 38 948 in 2013).

RESULTS

Among educated mothers, there was an increase in prevalence of exclusive breast-feeding (26% in 1999 to 30% in 2013) and predominant breast-feeding (27% in 1999 to 39% in 2013) compared with mothers with no schooling. A similar increasing trend was evident for mothers from wealthier households and mothers who had a higher frequency of health service access compared with mothers from poorer households and women who reported no health service access, respectively. Mothers with no schooling predominantly breast-fed, but the odds for bottle-feeding were higher among educated mothers and women from wealthier households. The odds for early initiation of breast-feeding were lower for mothers who reported no health service contacts and mothers of lower socio-economic status.

CONCLUSIONS

Significant increasing trends in key breast-feeding indicators were evident among mothers with higher socio-economic status and mothers who had more health service access in Nigeria. Broader national and sub-national policies that underpin nursing mothers in work environments and a comprehensive community-based approach are proposed to improve feeding practices in Nigeria.

The influence of early menopause on cardiovascular risk in women with rheumatoid arthritis

OBJECTIVE

Early menopause is associated with an increased risk for developing rheumatoid arthritis (RA). The risk for cardiovascular disease (CVD) in women increases following menopause. Because RA is associated with an increased risk of CVD, this study was undertaken to determine whether early menopause affects the risk of developing CVD in women with RA.

METHODS

A population-based inception cohort of 600 women with RA who fulfilled 1987 American College of Rheumatology criteria for RA between 1955 and 2007 and were age ≥ 45 years at diagnosis was assembled and followed. Age at menopause and duration of hormone replacement therapy, along with occurrence of CVD, was ascertained by review of medical records. Cox proportional hazard models compared women who underwent early menopause (natural or artificial menopause at age ≤ 45 yrs) to those within the cohort who did not undergo early menopause.

RESULTS

Of 600 women, 79 experienced early menopause. Women who underwent early menopause were at significantly higher risk for developing CVD when compared to women who did not (HR 1.56; 95% CI 1.08-2.26).

CONCLUSION

The risk of CVD in women with RA was higher in those who experienced early menopause, and like other known risk factors should increase clinician concern for development of CVD in these patients.

Is pregnancy a risk factor for rheumatic autoimmune diseases?

PURPOSE OF REVIEW

To review the association of pregnancy with the risk of subsequent development of rheumatic autoimmune diseases in women, including rheumatoid arthritis (RA), systemic lupus erythematosus, and scleroderma.

RECENT FINDINGS

There is a small but growing literature related to the risk of autoimmune rheumatic disease in association with pregnancy history. However, results conflict both in terms of the direction and magnitude of risk of disease in relationship to prior pregnancy history. Although anecdotal evidence tends to favor the premise that pregnancy is protective against certain diseases, such as RA, the heterogeneity of results precludes the ability to confirm an association in either direction. There is indication that time elapsed since pregnancy may influence risk, with the postpartum year being of particular relevance.

SUMMARY

To date, a clear pattern has not emerged regarding pregnancy and the future risk of autoimmune rheumatic diseases. This topic requires greater study, and given the strong female preponderance of these diseases, future research efforts should seek to resolve this important issue.

Reproductive history and postmenopausal rheumatoid arthritis among women 60 years or older: Third National Health and Nutrition Examination Survey

OBJECTIVE

Rheumatoid arthritis, a condition of unknown etiology, has been associated with considerable costs to society. The purpose of this study is to determine whether selected reproductive history characteristics are associated with postmenopausal rheumatoid arthritis diagnosis.

METHODS

Secondary analyses were performed using cross-sectional data from the Third National Health and Nutrition Examination Survey. Of 1,892 eligible participants, 182 fulfilled the criteria for postmenopausal rheumatoid arthritis, based on self-report and the 1987 American College of Rheumatology criteria. Logistic regression models were constructed, and odds ratios (ORs) with their 95% CIs were calculated for selected reproductive history characteristics as predictors of postmenopausal rheumatoid arthritis, after adjustment for potential confounders.

RESULTS

Multivariate logistic models suggested that age at menopause was the only reproductive characteristic that was significantly associated with the outcome of interest (OR, 0.96; 95% CI, 0.93-0.99). Compared with women experiencing menopause at 50 years of age or later, those who experienced menopause before 40 years of age (OR, 2.53; 95% CI, 1.41-4.53) had increased odds of postmenopausal rheumatoid arthritis.

CONCLUSIONS

Women who experience menopause before 40 years of age seem to be at increased risk for postmenopausal rheumatoid arthritis. Conversely, age at menarche and pregnancy history may not predict rheumatoid arthritis after menopause. Further research is needed to confirm and elucidate these epidemiological findings.

Breastfeeding practice, oral contraceptive use and risk of rheumatoid arthritis among Chinese women: the Guangzhou Biobank Cohort Study

OBJECTIVE

Hormonal and reproductive factors are implicated in the aetiology of RA, but results of previous studies have been mixed. The aim of this cross-sectional study was to assess the relationships between RA, use of oral contraceptives (OCs) and history of breastfeeding in a population of older women from South China.

METHODS

We used baseline data from 7349 women ≥ 50 years of age in the Guangzhou Biobank Cohort. Questionnaires were used to obtain socio-demographic, lifestyle and obstetric history data, including parity, OC use and breastfeeding practices. The main outcome was RA. Women were asked about history of RA and were examined to assess joint swelling. RF levels were measured. The presence of RA was defined in two ways: (i) as reporting physician-diagnosed RA or pain and swelling in at least three joints (including the wrist), and (ii) also having at least one of the following: positive RF, morning stiffness or objective swelling of the small joints of the hands.

RESULTS

Compared with those who had never breastfed, breastfeeding was associated with half the risk of RA. The risk was lower with increasing duration of breastfeeding [adjusted odds ratio (OR) 0.54 (95% CI 0.29, 1.01) for breastfeeding at least 36 months; P for trend = 0.04]. OC use had no relationship with RA.

CONCLUSION

Breastfeeding (especially longer duration) but not OC use is associated with a lower risk of RA. This has potentially important implications for future RA disease burden, given the declining rates of breastfeeding and the one-child policy in China. Further research is needed to explain the biological mechanism.

Environmental and gene-environment interactions and risk of rheumatoid arthritis

Multiple environmental factors including hormones, dietary factors, infections, and exposure to tobacco smoke, as well as gene-environment interactions, have been associated with increased risk for rheumatoid arthritis (RA). The growing understanding of the prolonged period before the first onset of symptoms of RA suggests that these environmental and genetic factors are likely acting to drive the development of RA-related autoimmunity long before the appearance of the first joint symptoms and clinical findings that are characteristic of RA. This article reviews these factors and interactions, especially those that have been investigated in a prospective fashion before the symptomatic onset of RA.

The swollen joint, the thickened artery, and the smoking gun: tobacco exposure, citrullination and rheumatoid arthritis

Autoimmune diseases result from an interplay between susceptibility genes and environmental factors. These interacting etiopathogenetic components converge in a critical step preceding disease, the loss of tolerance to self. In this review, we examine the evidences linking tobacco smoking with the initiation and perpetuation of inflammation affecting both the synovial membrane and the endothelial lining in patients with rheumatoid arthritis. This disease is a compelling argument for the decisive role of environment in the triggering of a human autoimmune disease in genetically prone individuals.

Does pregnancy provide vaccine-like protection against rheumatoid arthritis?

OBJECTIVE

Previous studies have evaluated the correlation between rheumatoid arthritis (RA) risk and pregnancy history, with conflicting results. Fetal cells acquired during pregnancy provide a potential explanation for modulation of RA risk by pregnancy. The present study was undertaken to examine the effect of parity on RA risk.

METHODS

We examined parity and RA risk using results from a population-based prospective study in Seattle, Washington and the surrounding area and compared women who were recently diagnosed as having RA (n = 310) with controls (n = 1,418). We also evaluated the distribution of parity in cases according to HLA genotype.

RESULTS

We found a significant reduction of RA risk associated with parity (relative risk [RR] 0.61 [95% confidence interval 0.43-0.86], P = 0.005). RA risk reduction in parous women was strongest among those who were younger. Most striking was that RA risk reduction correlated with the time that had elapsed since the last time a woman had given birth. RA risk was lowest among women whose last birth occurred 1-5 years previously (RR 0.29), with risk reduction lessening progressively as the time since the last birth increased (for those 5-15 years since last birth, RR 0.51; for those >15 years, RR 0.76), compared with nulliparous women (P for trend = 0.007). No correlation was observed between RA risk and either age at the time a woman first gave birth or a woman's total number of births. Among cases with the highest genetic risk of RA (i.e., those with 2 copies of RA-associated HLA alleles), a significant underrepresentation of parous women versus nulliparous women was observed (P = 0.02).

CONCLUSION

In the present study, there was a significantly lower risk of RA in parous women that was strongly correlated with the time elapsed since a woman had last given birth. While the explanation for our findings is not known, HLA-disparate fetal microchimerism can persist many years after a birth and could confer temporary protection against RA.

The PRL -1149 G/T polymorphism and rheumatoid arthritis susceptibility

OBJECTIVE

Previous studies have demonstrated that the PRL -1149 T (minor) allele decreases prolactin expression and may be associated with autoimmune disease. The aim of this study was to determine the role of the PRL -1149 G/T polymorphism (rs1341239) in rheumatoid arthritis (RA) susceptibility.

METHODS

We examined the association between PRL -1149 G/T and RA risk in 4 separate study populations, consisting of a total of 3,405 RA cases and 4,111 controls of self-reported white European ancestry. Samples were genotyped using 1 of 3 genotyping platforms, and strict quality control metrics were applied. We tested for association using a 2-tailed Cochran-Mantel-Haenszel additive, fixed-effects model.

RESULTS

In the individual populations, odds ratios (ORs) for an association between PRL -1149 T and RA risk ranged from 0.80 to 0.97. In a joint meta-analysis across all 4 populations, the OR for an association between PRL -1149 T and RA risk was 0.90 (95% confidence interval 0.84-0.96, P=0.001).

CONCLUSION

Our findings indicate a possible association between the PRL -1149 T allele and decreased RA risk. The effect size is small but similar to ORs for other genetic polymorphisms associated with complex traits, including RA.

Rheumatoid arthritis and reproduction

Additional research is needed to establish the safety of biologic agents in pregnancy and lactation. The practitioner should convey information regarding the natural history of rheumatoid arthritis during pregnancy and safety issues related to pharmacotherapies to every woman of childbearing age with RA, well before conception and pregnancy, to ensure optimal outcomes.

A review of the effects of breastfeeding on respiratory infections, atopy, and childhood asthma

The etiology of childhood asthma is not fully understood. Early exposure to certain respiratory infections may be protective for atopy and/or asthma whereas some infections have been suggested to exert the opposite effects. Wheezing lower respiratory illness (LRI) in the first year of life and atopy are independently associated with increased risk for current asthma in childhood and their effects are mediated via different causal pathways. These risk factors are multiplicative when they operate concommitantly within individual children. Exclusive breastfeeding protects against asthma via effects on both these pathways, as well as through other as yet undefined mechanisms. Furthermore, exclusive breastfeeding may protect against asthma and may reduce the incidence of lower respiratory illness, especially respiratory syncytial virus (RSV). We have previously demonstrated a protective effect of exclusive breastfeeding on asthmatic traits in children. The aim of this review was to clarify this protective association from intermediate associations with respiratory infections, atopy, or through other facets of breastfeeding. The bioactivity of breast milk and subsequent pathways that may act upon the development of asthma in children are explored.

Do breast-feeding and other reproductive factors influence future risk of rheumatoid arthritis?: Results from the Nurses' Health Study

OBJECTIVE

To explore the contribution of female hormonal factors occurring prior to the onset of rheumatoid arthritis (RA), such as age at menarche, parity, age at first birth, breast-feeding, use of oral contraceptives (OCs), irregular menstrual cycles, and postmenopausal hormone (PMH) use, to the subsequent development of RA in a large female cohort.

METHODS

We studied female reproductive and hormonal risk factors for RA in a cohort of 121,700 women enrolled in the longitudinal Nurses' Health Study. The diagnosis of incident RA (between 1976 and 2002) in 674 women was confirmed by a connective tissue disease screening questionnaire and blinded medical record review for American College of Rheumatology criteria. Sixty percent of the patients with RA were rheumatoid factor positive. The relationship between potential risk factors, including age, age at menarche, parity, age at first birth, total lifetime history of breast-feeding, use of OCs, and irregular menstrual cycles and the multivariate-adjusted risk of RA was estimated using Cox proportional hazards models.

RESULTS

Using a multivariate model that adjusted for age, body mass index, smoking, parity, and other hormonal factors, we observed a strong trend for decreasing risk of RA with increasing duration of breast-feeding (P for trend = 0.001). For women who breast-fed (compared with parous women who did not breast-feed), the risk ratios (RRs) and 95% confidence intervals (95% CIs) were as follows: breast-feeding for < or =3 total months, RR 1.0 (95% confidence interval [95% CI] 0.8-1.2); for 4-11 total months, RR 0.9 (95% CI 0.7-1.1); for 12-23 total months, RR 0.8 (95% CI 0.6-1.0); and for > or =24 total months, RR 0.5 (95% CI 0.3-0.8). Very irregular menstrual cycles were associated with an increased risk of RA (RR 1.4, 95% CI 1.0-2.0). Age at menarche < or =10 years was associated with an increased risk of seropositive RA (RR 1.6, 95% CI 1.1-2.4) but not significantly associated with risk of RA. Parity, total number of children, age at first birth, and OC use were not associated with an increased risk of RA in this cohort.

CONCLUSION

In this large cohort, breast-feeding for >12 months was inversely related to the development of RA. This apparent effect was dose-dependent, with a significant trend toward lower risk with longer duration of breast-feeding. Irregular menstrual cycles and earlier age at menarche increased the risk of RA. Other reproductive hormonal factors were not associated with RA risk.

Smoking, gender and rheumatoid arthritis–epidemiological clues to etiology

OBJECTIVES

This study was undertaken to confirm and extend our earlier observation that gender is a biological effect modifier of smoking-rheumatoid arthritis (RA) relationship in a diverse national survey sample in the United States.

METHODS

Smoking history of 644 cases of RA and 1509 geographically matched general population controls were compared using weighted logistic regression.

RESULTS

There were 644 respondents with RA (cases) and 1509 geographically matched controls. Cases were significantly younger, less educated, more likely to be single and female than controls. Among cases 57% were smokers while among controls 49% smoked. Among women, after adjusting for age, hysterectomy had an age adjusted odds ratio 1.45, (95% CI 0.99-2.10) and menopause an adjusted odds ratio 1.18 (95% CI 0.99-2.10) were associated with smoking. In univariable analysis ever-smoking was associated with increased risk of RA (odds ratio 1.34, 95% CI 1.0-1.81). Among the strata of smokers, there was an increasing gradient of risk with increasing exposure to smoking (P = 0.041). In separate multivariable models, smoking increased the risk in men (odds ratio 2.29, 95% CI 1.35-3.90) while in women the risk was not elevated (odds ratio 0.98, 95% CI 0.67-1.42). After adjusting for the statistically significant interaction both female gender (odds ratio 2.30, 95% CI 1.39-3.83) and having ever smoked (odds ratio 2.31, 95% CI 1.36-3.94) emerged as significant risk factors for RA.

CONCLUSIONS

Gender interacts with smoking in by an unknown mechanism to lead to differential risk of RA.

Estrogen and other female reproductive risk factors are not strongly associated with the development of rheumatoid arthritis in elderly women

OBJECTIVE

Endogenous and exogenous reproductive hormones have been associated with rheumatoid arthritis (RA) in women, but data are inconsistent and no studies have assessed RA risk factors exclusively in elderly women.

METHODS

The authors examined the association between reproductive factors, exogenous hormone exposure, and RA in a prospective cohort study of 31,336 Iowa women who were aged 55 to 69 years at cohort baseline in 1986.

RESULTS

During 11 years of follow-up, 158 incident cases of RA were identified and validated. Age at last pregnancy (P trend =.01) and age at menopause (P trend =.03) were inversely associated with RA, whereas a history of polycystic ovary syndrome (relative risk [RR], 2.58; 95% confidence interval [CI], 1.06 to 6.30), endometriosis (RR, 1.72; 95% CI, 0.93 to 3.18), and former use of hormone replacement therapy (RR, 1.47; 95% CI, 1.04 to 2.06) were positively associated with RA. In multivariate analysis models, a history of polycystic ovary syndrome remained the most consistent predictor of RA, whereas the RRs for other factors attenuated.

CONCLUSION

Few reproductive factors showed a strong or statistically significant association with RA in elderly women. The association of polycystic ovary syndrome may be indicative of perturbations of endocrine-immune activity that may influence the development of RA. This prospective cohort study adds to the understanding of the potential contribution of hormonal factors to the cause of RA in older women.

Environmental epidemiology and risk factors for autoimmune disease

It has long been recognized that environmental influences play an important role in the risk of developing chronic rheumatic disease. Defining specific pathogenic environmental mediators that may trigger the development or progression of autoimmune disease remains a focus of increasing investigative effort. Factors promoting disease may not be identical to factors that influence the severity or progression of the disorder. Human monozygotic twin studies, animal studies, and genetic models demonstrate that genetic influences strongly determine whether one will develop autoimmunity, however, genes affecting the metabolism of exogenous agents that may trigger disease expression have only recently drawn attention. In this article the authors review recent reports that advance our understanding of previously recognized environmental risk factors and challenge accepted beliefs that increased estrogenic exposures predate the incidence of autoimmune disorders, systemic lupus erythematosus in particular.

Smoking-gender interaction and risk for rheumatoid arthritis

The present case-control study was conducted to investigate the relationship between smoking and rheumatoid arthritis, and to investigate formally the interaction between sex, smoking, and risk for developing rheumatoid arthritis. The study was performed in the Central District of Finland. Cases were patients with rheumatoid arthritis and the control group was a random sample of the general population. Logistic regression models were used to evaluate the effect of smoking on risk for rheumatoid arthritis, after adjusting for the effects of age, education, body mass index, and indices of general health and pain. Overall, 1095 patients with rheumatoid arthritis and 1530 control individuals were included. Patients were older, less well educated, more disabled, and had poorer levels of general health as compared with control individuals (all P < 0.01). Preliminary analyses revealed the presence of substantial statistical interaction between smoking and sex (P < 0.001). In separate multivariable analyses, past history of smoking was associated with increased risk for rheumatoid arthritis overall in men (odds ratio 2.0, 95% confidence interval 1.2-3.2) but not in women. Among men, this effect was seen only for rheumatoid factor-positive rheumatoid arthritis. There were significant interactions between smoking and age among women but not among men. We conclude that sex is a biologic effect modifier in the association between smoking and rheumatoid arthritis. The role of menopause in the etiology of rheumatoid arthritis merits further research.

The association between gravidity and primary biliary cirrhosis

PURPOSE

Primary biliary cirrhosis is an autoimmune disease with female predominance that leads to liver failure. The goal of this study was to identify reproductive risk factors associated with this disease.

METHODS

We compared 182 cases of PBC with 225 age- and sex-matched friend controls to examine the role of reproductive factors. The survey instrument was developed using standardized questions obtained from the National Health and Nutrition Examination Survey (NHANES) III.

RESULTS

A total of 126/182 cases (69%) and 141/225 (62.6%) friend controls responded to the survey. More cases than controls reported ever having genitourinary infection [adjusted odds ratio (OR) = 2.12, 95% confidence interval (CI) 1.01, 4.42] among those without a personal or family history of autoimmune disease. The most notable finding was that cases reported significantly more pregnancies than controls (p = 0.008). The adjusted OR for each additional pregnancy among those without a personal or family history of autoimmune disease was 1.40 (95% CI 1.14, 1.7). More controls (24.4%) than cases (16.0%) were nulliparous. Cases reported having five or more children (16.0%) with double the frequency of controls (8.2%).

CONCLUSIONS

The association reported herein, between primary biliary cirrhosis and gravidity, is particularly significant because of the overwhelming female predominance.

Comorbidity and lifestyle, reproductive factors, and environmental exposures associated with rheumatoid arthritis

OBJECTIVE

To evaluate the influence of lifestyle, reproduction, and some external factors on the development of rheumatoid arthritis (RA) and to describe its comorbidity.

METHODS

Cases were identified retrospectively from 1980 to 1995 at the University Hospital in Linköping, Sweden. The study comprised 422 cases and 859 randomly selected population referents. Data on possible aetiological factors and comorbidity were collected by postal questionnaire.

RESULTS

The response rates were 67% among cases and 59% among referents. A decrease in the occurrence of atopic allergy was seen in the cases (odds ratio (OR) 0.6, 95% confidence interval (CI) 0.4 to 1.0). There was a positive association between RA and insulin treatment (OR 10.2, 95% CI 1.7 to 60.8) in women, and women with a short fertile period had an increased risk of RA (OR 2.5, 95% CI 1.1 to 5.4). Current and previous smoking were associated with increased risks for RA in both sexes, and in men a dose-response relationship was found with number of tobacco pack years (p for trend <0.005). The risk for RA decreased with increasing level of education in both men and women. Increased risks were seen in men born into households with private wells (OR 2.8, 95% CI 1.5 to 5.2), residentially exposed to mould (OR 4.6, 95% CI 1.1 to 20.2), or exposed to farm animals (OR 3.3, 95% CI 0.7 to 16.6). In women there were positive associations between RA and reporting a previous joint injury (OR 2.5, 95% CI 1.0 to 6.6) and prolonged exposure to hair dyes (OR 1.9, 95% CI 0.8 to 4.5).

CONCLUSIONS

RA, a disease with features of T helper 1 (Th1) dominated immune response, was inversely associated with atopic allergy, a Th2 dominated condition, while there were indications of a strong positive association with Th1 related diabetes mellitus. The results support a causal relationship between smoking and RA. The level of education was inversely associated with RA, while there was a positive association between RA and certain residential factors in men and a short fertile period in women.

Cumulative duration of breast-feeding influences cortisol levels in postmenopausal women

Cortisol levels dramatically increase during pregnancy, peak at birth, and subsequently decline. However, all previous studies examined women during pregnancy and early postpartum. None examined the long-term association of parity and lactation with cortisol levels. We examined the relation of reproductive history to cortisol levels in postmenopausal women. Subjects were 749 women, aged 50-89, who were not using estrogen in 1984-1987 when morning cortisol was measured. Parity was not significantly associated with cortisol. However, women who breast-fed for >12 months had significantly higher cortisol levels than women who breast-fed for shorter durations or not at all (p = 0.003). This association was stronger among women with three or more births. Duration of breast-feeding is a determinant of cortisol levels in postmenopausal women. Because both increased cortisol and increased duration of breast-feeding may play protective roles in certain autoimmune diseases, such as rheumatoid arthritis, we suggest that the beneficial effect of lactation on the course of these diseases may be mediated by cortisol.

Menopause, oestrogens and arthritis

The menopause coincides with the appearance of many of the common arthritic conditions and with the lessening of severity of others such as SLE. The hormonal changes that occur may modulate these diseases. Thus, hormonal manipulation may have either beneficial or detrimental effects on the incidence and activity of a number of common joint diseases. We review the evidence regarding the effect of the menopause and oestrogen replacement therapy on the pathogenesis, incidence and prevalence and disease activity of osteoarthritis, rheumatoid arthritis, systemic lupus erythematosus and carpal tunnel syndrome.

Human milk and host defence: immediate and long-term effects

Convincing studies demonstrate significant protection during breastfeeding against diarrhoea, respiratory tract infections, otitis media, bacteraemia, bacterial meningitis, botulism, urinary tract infections and necrotizing enterocolitis. There is also good evidence for enhanced protection for years after the termination of breastfeeding against Haemophilus influenzae type b infections, otitis media, diarrhoea, respiratory tract infections and wheezing bronchitis. In some reports breastfeeding has also improved vaccine responses. Several studies show that milk may actively stimulate the immune system of the offspring via transfer of anti-idiotypic antibodies and lymphocytes. This may explain why breastfeeding diminishes the risk of developing coeliac disease. Some investigations suggest that there may also be a similar effect on allergic diseases and autoimmune diseases, as well as inflammatory bowel diseases and certain tumours. This needs to be confirmed.

Sex hormones and pregnancy in rheumatoid arthritis and systemic lupus erythematosus

Rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) are autoimmune disorders with a preponderance in females. RA and SLE differ in their response to sex hormones. Disease development of RA is mitigated by estrogen and pregnancy whereas SLE tends to flare during pregnancy and in response to estrogen. Pregnancy improves the symptoms of RA in about 75% of pregnant patients, but relapses within six months postpartum in 90% of cases. RA is regarded as a T cell-mediated and TH1 immune response-driven disease. Pregnancy induces a shift from TH1 to TH2 immune response, increasing the anti-inflammatory cytokines IL-4 and IL-10, which may contribute to gestational amelioration of RA. Prospective studies of SLE pregnancies indicate that about 50% of patients experience a flare, however, with no permanent aggravation of the disease. Lupus nephritis, presence of antiphospholipid antibodies, and a previous history of pregnancy loss increase the risk of complications during pregnancy and fetal loss. The marked increase of estrogen and progesterone during pregnancy seems to enhance some of the manifestations of SLE. The shift to a TH2 immune response may trigger SLE manifestations that are dependent on humoral immune responses such as lupus nephritis. Another factor stimulating immune responses is the pituitary hormone prolactin, which has been found elevated in SLE patients of both sexes and correlated to disease activity in several studies. The hyperprolactinemia of lactation seems to influence postpartum behavior of SLE as well as RA.

A retrospective cohort study of cigarette smoking and risk of rheumatoid arthritis in female health professionals

OBJECTIVE

To study the association of cigarette smoking with risk of rheumatoid arthritis (RA), among 377,481 female health professionals in the Women's Health Cohort Study.

METHODS

Subjects completed mailed questionnaires regarding demographics, health habits, including cigarette smoking history, and medical history, including RA diagnosis made by a physician and date of diagnosis. Of 7,697 women who self-reported RA, 3,416 reported seropositive RA. Cox proportional hazards regression models were used to retrospectively assess the associations of smoking intensity and duration with the risk of developing RA or seropositive RA. Cigarette smoking status was treated as a time-varying exposure in these regression models.

RESULTS

In multivariate analyses controlling for age, race, education, age at menarche, pregnancy history, menopausal status, and postmenopausal hormone use, duration of smoking was associated with a significantly increased risk of both RA and seropositive RA (both P < 0.01 for trend), after adjusting for smoking intensity. Women who smoked > or =25 cigarettes/day for more than 20 years experienced a 39% increased risk of RA and 49% increased risk of seropositive RA. However, smoking intensity (number of cigarettes/day) was unrelated to risk of RA or seropositive RA (both P = 0.3 for trend), after adjusting for duration of smoking.

CONCLUSION

Duration, but not intensity, of cigarette smoking is associated with a modest increased risk of RA in women.

Breastfeeding provides passive and likely long-lasting active immunity

OBJECTIVES

The reader of this review will learn about the mechanisms through which breastfeeding protects against infections during and most likely after lactation, as well as possibly against certain immunologic diseases, including allergy.

DATA SOURCES

I have followed the literature in the area closely for the last 30 to 40 years and have made repeated literature searches through MEDLINE, most recently in 1998. Textbooks and peer-reviewed journals have been sought for, as well as books representing meeting reports in English, French, German, and Spanish.

RESULTS

Human milk protects against infections in the breastfed offspring mainly via the secretory IgA antibodies, but also most likely via several other factors like the bactericidal lactoferrin. It is striking that the defense factors of human milk function without causing inflammation, some components are even directly anti-inflammatory. Protection against infections has been well evidenced during lactation against, e.g., acute and prolonged diarrhea, respiratory tract infections, otitis media, urinary tract infection, neonatal septicemia, and necrotizing enterocolitis. There is also interesting evidence for an enhanced protection remaining for years after lactation against diarrhea, respiratory tract infections, otitis media, Haemophilus influenzae type b infections, and wheezing illness. In several instances the protection seems to improve with the duration of breastfeeding. Some, but not all studies have shown better vaccine responses among breastfed than non-breastfed infants. A few factors in milk like anti-antibodies (anti-idiotypic antibodies) and T and B lymphocytes have in some experimental models been able to transfer priming of the breastfed offspring. This together with transfer of numerous cytokines and growth factors via milk may add to an active stimulation of the infant's immune system. Consequently, the infant might respond better to both infections and vaccines. Such an enhanced function could also explain why breastfeeding may protect against immunologic diseases like coeliac disease and possibly allergy. Suggestions of protection against autoimmune diseases and tumors have also been published, but need confirmation.

CONCLUSIONS

Breastfeeding may, in addition to the well-known passive protection against infections during lactation, have a unique capacity to stimulate the immune system of the offspring possibly with several long-term positive effects.

Breastfeeding and women's health

Breastfeeding often is promoted mainly as an infant health issue, with little if any mention of its importance to the mother's health. Despite its significant impact on women's health, breastfeeding is rarely emphasized in women's health programs. This article reviews the current medical literature regarding women's health aspects of breastfeeding, including medical, psychosocial, and environmental issues. Strategies for increasing health care professionals' awareness and promotion of breastfeeding as a women's health issue are discussed in the hope of reversing the worldwide decline in breastfeeding.

Oral contraception, parity, breast feeding, and severity of rheumatoid arthritis

OBJECTIVE

To investigate the influence of breast feeding, use of the oral contraceptive pill (OCP), and parity on rheumatoid arthritis (RA).

METHODS

One hundred and seventy six women with RA were compared with 145 control subjects; all had at least one child. RA patients were classified as having severe (n = 82) or mild disease (n = 89) according to clinical joint evaluation, radiological score, biological inflammation, and the presence of HLA-DR1 or -DR4 alleles.

RESULTS

The mean age of RA patients was 58 years, and the mean age at the time of diagnosis of RA was 46 years. The mean time between onset of RA and the first birth was 23.6 (SD 3.8) years. The OCP user rates were 33% in the RA group and 47.6% in the control group (p < 0.02). OCP use was related to the mother's year of birth. The relative risk for developing RA was 0.598 (95% confidence interval (CI) 0.33 to 1.1) in women who had used OCP for more than five years compared with those who had never used OCPs. In contrast, the age at which the first pregnancy occurred, the number of children breast fed, and the duration of breast feeding were comparable in RA patients and healthy subjects. Among the RA patients, parity, duration of breast feeding, and the number of breast fed children were significantly increased in those with severe disease. Having more than three children increased the risk of developing severe disease 4.8-fold when adjusted for age and OCP use. Forty six percent of women with severe RA had a history of breast feeding duration greater than six months before disease onset, compared with 26% of patients with mild disease (p < 0.008). Having more than three breast fed children increased the risk of poor disease prognosis 3.7-fold. In contrast, OCP use had a protective role in the course of RA (44% of RA patients with mild disease were OCP users, compared with 21.7% of those with severe RA; p < 0.001). Among those using OCP for more than five years, the relative risk of developing severe disease was 0.1 (95% CI 0.01 to 0.6), after adjustment for age, parity, and breast feeding.

CONCLUSION

Our results suggest that parity, and to a lesser extent breast feeding, before RA onset worsened RA prognosis, whereas OCP use had a protective role. Prolactin and oestrogen may have a role in these effects.