Association of infertility with premature mortality among US women: Prospective cohort study

History of infertility and anti-Müllerian hormone levels among participants in the Nurses' Health Study II

OBJECTIVES

To better understand whether history of infertility is associated with anti-Müllerian hormone (AMH) levels later in life, outside of reproduction.

METHODS

Among 1,758 premenopausal women in the Nurses' Health Study II with measured AMH, we used multivariable generalized linear models to compare log-transformed plasma AMH for women with a history of infertility compared with fertile women. We investigated AMH levels by cause of infertility and effect modification by menstrual cycle regularity. Lastly, we investigated AMH levels by history of primary and secondary infertility and age at reported infertility.

RESULTS

Mean age at blood collection was 40 years. We observed no association between overall history of infertility and AMH levels (% difference AMH: -8.1% [CI, -19.4 to 4.8]). The association between overall infertility and AMH was strongest among women who first reported infertility at >30 years (-17.7% [CI, -32.1 to -0.3]).

CONCLUSIONS

Overall, we observed no association between the history of infertility and AMH levels later in life. However, specific subgroups of women with a history of infertility may have lower AMH levels throughout life compared with fertile women. This association was observed among subgroups, such as those who first experienced infertility at >30 years. These findings have implications for mechanisms through which infertility may be associated with premature menopause and chronic disease risk.

Association between female infertility and stroke mortality: evidence from the PLCO cancer screening trial

Objective

While infertility affects about 15% of women during their reproductive years, its long-term impact on stroke mortality after this period remains unclear. This study aims to investigate the association between infertility and stroke mortality in women using data from the Prostate, Lung, Colorectal, and Ovarian (PLCO) cancer screening trial.

Methods

We analyzed data from 75,778 female participants aged 55-74 years with a median follow-up of 16.84 years. Cox proportional hazard models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for stroke mortality, adjusting for potential confounders.

Results

Among participants, 14.53% reported infertility. During follow-up, 1,159 women died from stroke. Compared to women without infertility, those with infertility had a higher risk of stroke mortality (HR 1.21, 95% CI 1.04-1.41, p = 0.016). This association remained statistically significant after adjusting for age, race, education level, marital status, smoking status, body mass index, history of hypertension, history of heart attack, history of diabetes mellitus, birth control pill use, hormone replacement therapy, endometriosis, first menstrual period and pregnancy history (HR 1.20, 95% CI 1.02-1.42, p = 0.029). Sensitivity and subgroup analyses yielded consistent results.

Conclusion

The findings of this study indicate that infertility is associated with an increased risk of stroke mortality in women. Further research is needed to confirm these findings and elucidate the underlying mechanisms.

Reproductive genetics and health

For those affected, infertility is linked to impaired overall health and reduced life expectancy. In particular, infertile individuals bear an increased risk for cardiovascular disease (CVD) and different types of cancer, partially due to lifestyle differences and to genetic alterations that cause both infertility and an increased cancer risk. Genetic variants causing an increased CVD risk are more commonly found in infertile individuals, but their link to infertility remains unclear. Offspring of infertile couples, conceived via medically assisted reproduction, are as likely as their parents to exhibit or develop adiposity, hormonal alterations such as insulin resistance, and infertility. The effects on health of subsequent generations are completely unclear.

History of Infertility and Midlife Cardiovascular Health in Female Individuals

Importance

Fertility status is a marker for future health, and infertility has been associated with risk for later cancer and diabetes, but associations with midlife cardiovascular health (CVH) in female individuals remain understudied.

Objective

To evaluate the association of infertility history with CVH at midlife (approximately age 50 years) among parous individuals.

Design, Setting, and Participants

Project Viva is a prospective cohort study of pregnant participants enrolled between 1999 and 2002 who delivered a singleton live birth in the greater Boston, Massachusetts, area. Infertility history was collected at a midlife visit between 2017 and 2021, approximately 18 years after enrollment. Data analysis was performed from January to June 2023.

Exposures

The primary exposure was any lifetime history of infertility identified by self-report, medical record, diagnosis, or claims for infertility treatment.

Main Outcomes and Measures

The American Heart Association's Life's Essential 8 (LE8) is a construct for ranking CVH that includes scores from 0 to 100 (higher scores denote better health status) in 4 behavioral (diet, physical activity, sleep, and smoking status) and 4 biomedical (body mass index, blood pressure, blood lipids, and glycemia) domains to form an overall assessment of CVH. Associations of a history of infertility (yes or no) with mean LE8 total, behavioral, biomedical, and blood biomarker (lipids and glycemia) scores were examined, adjusting for age at outcome (midlife visit), race and ethnicity, education, household income, age at menarche, and perceived body size at age 10 years.

Results

Of 468 included participants (mean [SD] age at the midlife visit, 50.6 [5.3] years) with exposure and outcome data, 160 (34.2%) experienced any infertility. Mean (SD) LE8 scores were 76.3 (12.2) overall, 76.5 (13.4) for the behavioral domain, 76.0 (17.5) for the biomedical domain, and 78.9 (19.2) for the blood biomarkers subdomain. In adjusted models, the estimated overall LE8 score at midlife was 2.94 points lower (95% CI, -5.13 to -0.74 points), the biomedical score was 4.07 points lower (95% CI, -7.33 to -0.78 points), and the blood subdomain score was 5.98 points lower (95% CI, -9.71 to -2.26 points) among those with vs without history of infertility. The point estimate also was lower for the behavioral domain score (β = -1.81; 95% CI, -4.28 to 0.66), although the result was not statistically significant.

Conclusions and Relevance

This cohort study of parous individuals found evidence for an association between a history of infertility and lower overall and biomedical CVH scores. Future study of enhanced cardiovascular preventive strategies among those who experience infertility is warranted.

Exploring the relationship between history of infertility and the experience of menopausal symptoms

OBJECTIVE

The aim of the study is to examine longitudinal associations of history of infertility with menopausal symptoms in midlife.

METHODS

Six hundred ninety-five midlife women (≥45 y old or reporting ≥12 mo of amenorrhea at the midlife visit) in Project Viva, a prospective cohort enrolled 1999-2002 during pregnancy and followed for 18 years after enrollment ("midlife visit"). Exposure was history of infertility defined as time to pregnancy ≥12 months (≥6 mo if ≥35 y), use of medical treatment to conceive, or infertility consultation or treatment in the 6-month preceding enrollment. The primary outcome was score below or above the median on the Menopause Rating Scale (MRS). Secondary outcomes included individual symptom score on the MRS and self-reported age of menopause.

RESULTS

A total of 36.6% had a history of infertility in their lifetime. At the time of MRS completion, the women with prior infertility were older (53.4 [SD, 3.8] vs 51.2 [SD, 3.7] y) than those without infertility and a larger proportion had reached menopause (62% vs 40%). Women with prior infertility were more likely to score above the median on the MRS (Adjusted Odds Ratio [aOR], 1.45; 95% confidence interval [CI], 1.04-2.01) and had higher odds for reporting any depressive mood (aOR, 1.56; 95% CI, 1.12-2.16) and irritability (aOR, 1.57; 95% CI, 1.13-2.19). There was a trend toward greater severity of sleep problems among women with prior infertility. There was no association of prior infertility with report of other menopausal symptoms or age of menopause.

CONCLUSIONS

Our findings suggest that women with prior infertility are more likely to have an MRS score above the median and experience depressive mood, irritability, and sleep problems during midlife than women without infertility. These findings have implications for mental health screening among midlife women.

A prospective cohort study of infertility and cancer incidence

OBJECTIVE

To investigate the association between infertility and the incidence of invasive cancer.

DESIGN

Prospective cohort study (1989-2015).

SETTING

Not applicable.

PATIENT(S)

A total of 103,080 women aged 25-42 years in the Nurses' Health Study II who were cancer-free at baseline (1989).

INTERVENTION(S)

The infertility status (failure to conceive after 1 year of regular, unprotected sex) and causes of infertility were self-reported at baseline and biennial follow-up questionnaires.

MAIN OUTCOME MEASURE(S)

Cancer diagnosis was confirmed through medical record review and classified as obesity-related (colorectal, gallbladder, kidney, multiple myeloma, thyroid, pancreatic, esophageal, gastric, liver, endometrial, ovarian, and postmenopausal breast) or non-obesity-related (all other cancers). We fit the Cox proportional-hazards models to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) of the association between infertility and cancer incidence.

RESULT(S)

During 2,149,385 person-years of follow-up, 26,208 women reported a history of infertility, and we documented 6,925 incident invasive cancer cases. After adjusting for body mass index and other risk factors, women who reported infertility had a higher risk of developing cancer than gravid women without a history of infertility (HR, 1.07; 95% CI, 1.02-1.13). This association was stronger among obesity-related cancers (HR, 1.13; 95% CI, 1.05-1.22; vs. non-obesity-related cancers, HR, 0.98; 95% CI, 0.91-1.06) and, in particular, obesity-related reproductive cancers (postmenopausal breast, endometrial, and ovarian cancers; HR, 1.17; 95% CI, 1.06-1.29) and was stronger among women who first reported infertility earlier in life (≤25 years, HR, 1.19; 95% CI, 1.07-1.33; 26-30 years, HR, 1.11; 95% CI, 0.99-1.25; >30 years, HR, 1.07; 95% CI, 0.94-1.22; P trend < .001).

CONCLUSION(S)

A history of infertility may be associated with the risk of developing obesity-related reproductive cancers; further study is needed to elucidate the underlying mechanisms.

History of infertility and risk of breast cancer: a prospective cohort study

PURPOSE

Research on infertility and risk of breast cancer has been conflicting, potentially because many well-established breast cancer risk factors, such as pregnancy history, are strongly correlated with infertility.

METHODS

We followed participants in the Nurses' Health Study II from 1989 to 2015 (n = 103,080) for the development of invasive breast cancer and calculated Hazard Ratios (HR) and 95% confidence intervals (CI) using Cox regression. Participants with a self-reported history of infertility (12 months of trying without conception) were compared to gravid women with no history of infertility. We classified breast cancer by menopausal status and investigated mediation by reproductive factors.

RESULTS

Over 26 years of follow-up, 26,208 (25.4%) women reported a history of infertility, and 3,201 women were newly diagnosed with invasive breast cancer. We observed no association between infertility history and risk of overall breast cancer (HR: 1.05, 95% CI: 0.97-1.14) or premenopausal breast cancer (RR: 0.93, 95% CI: 0.83-1.03). However, we observed a modest association between history of infertility and risk of postmenopausal breast cancer (HR: 1.13, 95% CI: 1.00-1.28), approximately 50% of which could be attributed to lower total parity and later age at first birth (95% CI: 8.2%-91.0%).

CONCLUSIONS

Women with a history of infertility were at increased risk of postmenopausal breast cancer. Older age at first birth and lower total parity explained approximately half of the association between infertility and risk of postmenopausal breast cancer.

Infertility and Risk of Cardiovascular Disease: A Prospective Cohort Study

Background Certain symptoms associated with infertility are associated with cardiovascular disease, including menstrual cycle irregularity, early menopause, and obesity; however, few studies have investigated the association between infertility and cardiovascular disease risk. Methods and Results Participants in the NHSII (Nurses' Health Study II) who reported infertility (12 months of trying to conceive without success, including women who subsequently conceived) or who were gravid, with no infertility were followed from 1989 until 2017 for development of incident, physician-diagnosed coronary heart disease (CHD) (myocardial infarction, coronary artery bypass grafting, angioplasty, stent) and stroke. Time-varying Cox proportional hazard models were used to calculate hazard ratios (HRs) and 95% CIs and were adjusted a priori for potential confounding variables. Among 103 729 participants, 27.6% reported having ever experienced infertility. Compared with gravid women who had not reported infertility, women with a history of infertility had greater risk of CHD (HR, 1.13 [95% CI, 1.01-1.26]) but not stroke (HR, 0.91 [95% CI, 0.77-1.07]). The association between history of infertility and CHD was strongest among women who reported infertility at an earlier age (HR for infertility first reported at ≤25 years, 1.26 [95% CI, 1.09-1.46]; HR at 26-30 years, 1.08 [95% CI, 0.93-1.25]; HR at >30 years, 0.91 [95% CI, 0.70-1.19]). When we investigated specific infertility diagnoses, elevated risk of CHD was observed among women whose infertility was attributed to an ovulatory disorder (HR, 1.28 [95% CI, 1.05-1.55]) or endometriosis (HR, 1.42 [95% CI, 1.09-1.85]). Conclusions Women with infertility may be at an increased risk of CHD. Risk differed by age at first infertility diagnosis and was restricted to ovulatory- and endometriosis-related infertility.

Hypothalamic-Pituitary-Gonadal Axis Disorders Impacting Fertility in Both Sexes and the Potential of Kisspeptin-Based Therapies to Treat Them

Impaired function of the hypothalamic-pituitary-gonadal (HPG) axis can lead to a vast array of reproductive disorders some of which are inherited or acquired, but many are of unknown etiology. Among the clinical consequences of HPG impairment, infertility is quite common. According to the latest report from the World Health Organization, the global prevalence of infertility during a person's lifetime is a staggering 17.5% which translate into 1 out of every 6 people experiencing it. In both sexes, infertility is associated with adverse health events, and if unresolved, infertility can cause substantial psychological stress, social stigmatization, and economic strain. Even though significant advances have been made in the management and treatment of infertility, low or variable efficacy of treatments and medication adverse effects still pose a significant problem. However, the discovery that in humans inactivating mutations in the gene encoding the kisspeptin receptor (Kiss1R) results in pubertal failure and infertility has expanded our understanding of the mechanisms underlying the neuroendocrine control of reproduction, opening up potential new therapies for the treatment of infertility disorders. In this chapter we provide an overview of common infertility disorders affecting men and women, their recommended treatments, and the potential of kisspeptin-based pharmacotherapies to treat them.