Unexplained infertility: does it really exist? Does it matter?

Cytokine and chemokine profiles in women with endometriosis, polycystic ovary syndrome, and unexplained infertility

Numerous factors (including immunological, congenital, hormonal, and morphological disorders) can lead to infertility. In this regard, 3 specific diseases associated with infertility are discussed in this review study (i.e., polycystic ovary syndrome [PCOS], endometriosis [EMS], and unexplained infertility [UI]). PCOS is a common endocrine disorder characterized by chronic low-grade inflammation, and EMS is a benign disease characterized by the presence of ectopic endometrial tissue. UI refers to couples who are unable to conceive for no known reason. Conception and pregnancy are significantly affected by the immune system; in this regard, chemokines and cytokines play important roles in the regulation of immune responses. Patients with PCOS, EMS, and UI have altered cytokine and chemokine profiles, suggesting that dysregulation of these molecules may contribute to infertility in these conditions. Accordingly, the issue of infertility is addressed in this review study, a condition that affects approximately 16% of couples worldwide.

Subfertility as Overlapping of Nutritional, Endocrine, Immune, and Cardiometabolic Dysregulations-A Study Focused on Biochemical Endophenotypes of Subfertile Couples

Subfertility is a global health issue, and as many as 30% of cases are attributed to unexplained reasons. A hypercaloric, high-fat diet stimulates the expansion of pro-inflammatory gut microbiota with a consequent rise in circulating lipopolysaccharides. Adverse gut microbiota remodeling can exacerbate insulin resistance, while sex and thyroid hormones may influence the variability in gut microbiota. This cross-sectional study included 150 participants and was designed to determine a biochemical, nutritional-related pattern that may distinguish subfertile from fertile individuals and couples. A panel of 28 biomarkers was assessed. Four biochemical phenotypes of unexplained subfertility were found, including two metabolic and two immune, when assessed using binary logistic regression models. Two phenotypes were distinguished in women: cardio-metabolic with atherogenic dyslipidemia (LowHDL-cholesterol: OR = 10.9; p < 0.05) and autoimmune thyroid disorder (Highanti-thyroid-peroxidase: OR = 5.5; p < 0.05) and two in men: hepato-metabolic with elevated liver injury enzymes (HighHOMA-IR: OR = 6.1; p < 0.05) and immune type-2 response (HighIgE: OR = 6.4; p < 0.05). The chances of a couple's subfertility rose with the number of laboratory components of metabolic syndrome in the couple (OR = 1.7; p < 0.05) and if at least one partner had an elevated total IgE level (>100 kU/L) (OR = 6.5; p < 0.05). This study found that unexplained subfertility may be accompanied by mutually overlapping immune and metabolic dysregulations in individuals and couples. We propose one-time laboratory diagnostics taking into account the lipid profile, insulin resistance, anti-thyroid-peroxidase, and total IgE in both males and females with unexplained subfertility. This may allow for a one-time assessment of targeted medical and nutritional interventions and help optimize patients' health. The gut-organ axes related to subfertility are discussed in the context of the obtained results.

Impact of tubal patency test selection on the live birth rate following intrauterine insemination in couples with unexplained infertility: a retrospective cohort study

OBJECTIVE

We planned a study to evaluate the impact of selecting hysterosalpingography (HSG) over diagnostic laparoscopy during initial fertility evaluation on IUI treatment outcomes in couples diagnosed with unexplained infertility.

METHODS

The study comprised a retrospective cohort and included couples evaluated for infertility at our tertiary level hospital between January 2008 and December 2019. Couples diagnosed with unexplained infertility based on tubal patency tests (either HSG or diagnostic laparoscopy) were included. We compared outcomes following ovarian stimulation (OS) and intrauterine insemination (IUI) between women who underwent HSG versus laparoscopy for up to three treatment cycles.

RESULTS

A total of 7413 women were screened, out of which 1002 women were diagnosed with unexplained infertility. We did not find a significant statistical difference in the clinical pregnancy (16.7% vs. 11.7%; OR (odds ratio) 1.51; 95% CI (confidence interval) 0.90-2.5) or live birth rate per IUI cycle (15.1% vs. 10.7%; OR 1.51, 95% CI 0.9-2.6) in women who underwent HSG for tubal evaluation as compared to laparoscopy. After adjustment for potential confounders through multivariate analysis, we found that outcomes were comparable between the HSG and laparoscopy.

CONCLUSION

The current study did not find any significant difference in treatment outcomes following OS and IUI in women with unexplained infertility who underwent HSG compared to laparoscopy for the assessment of the tubal patency during the initial fertility workup. The finding suggests minimal or no impact of selecting HSG over diagnostic laparoscopy as a tubal patency test on the subsequent IUI outcomes.

The effect of controlled ovarian hyperstimulation on ovarian reserve via PTEN pathway

Abstract

This study was carried out to investigate whether repeated controlled ovarian hyperstimulation (COH) affects ovarian reserve. For this reason, we aimed to show possible changes in the expression of PTEN and FOXO3, which are involved in preserving the over-reserve, after applying the COH protocol methods. For this purpose, 18 young Wistar albino female rats (8 weeks old) were randomly assigned as group 1 (control), group 2, and group 3 as 6 subjects in each group. Experimental groups were treated with 10 IU/0.1 mL pregnant mare's serum gonadotropin and a COH protocol consisting of 10 IU/0.1 mL human chorionic gonadotropin injection after 48 h. This procedure was applied three and five times to group 2 and group 3, respectively. For the control groups, the same procedures were performed with 0.1 mL of 0.9% sodium chloride solution. At the end of the experiment, the ovarium tissues were placed in a 10% neutral formaldehyde solution for light microscopic examinations. In histological sections stained with hematoxylin and eosin, the number of ovarian follicles was determined using the physical dissector method. However, the expression of PTEN, FOXO3, and LH-R molecules was evaluated by immunohistochemical methods. As a result of our study, it was concluded that COH administration reduces the expression levels of PTEN and FOXO3 proteins and LH-R, which are among the essential components of the PIK3 intracellular signaling pathway and also increased the levels of hormones such as follicle-stimulating hormone, estradiol, and luteinizing hormone, which are over-reserve markers, and causes adverse effects on the histological structure, oocyte morphology, and number of ovaries.

Lay summary

Today, approximately 10-15% of couples experience fertility problems. However, assisted reproductive techniques help people with fertility problems to get pregnant. The main purpose of these techniques is to put the sperm and egg together outside the woman's body where the eggs are fertilized and then to return the fertilized eggs (embryos) to the womb. During a woman's menstrual cycle, several hormones influence the growth of the eggs. This process can be mimicked by using various medications. Medication is given to increase the number of eggs that develop. However, this method is not the same as normal ovulation. Therefore, in our study, we wanted to examine the effect that developing multiple follicles has on the number and quality of eggs remaining for the future.

Expectant Management Before In vitro Fertilization in Women Aged 39 or Above and Unexplained Infertility Does Not Decrease Live Birth Rates Compared to Immediate Treatment

Unexplained infertile couples can have further expectant management before starting assisted reproductive treatments. However, ovarian reserve and in vitro fertilization (IVF) outcomes rapidly decline after 39 years or more. It is thus important to clarify whether a waiting policy is also appropriate for women of advanced age. Couples who had access to a waiting list for approximately 1 year before receiving reimbursed public IVF were compared with those paying for access to immediate treatment. To allow for comparisons between these two strategies, we followed up couples who opted to pay for 1 year after the last embryo transfer from their first cycle. We calculated the proportion of live births in both groups and compared these using logistic regression models and a two-sample Z test for equality of proportions. Six hundred thirty-five couples were evaluated. Out of 359 couples in the immediate group, 70 (19.5%) had a live birth of which 11 after natural conception and 59 after IVF. Out of 276 couples in the waiting group, 57 (20.7%) had a live birth of which 37 after natural conception and 20 after IVF. There was no statistically significant difference between the two strategies in terms of the crude cumulative live birth rate (cLBR). The adjusted odds ratio of 0.69 (95%CI:0.39–1.22) did not change this conclusion as our sensitivity analyses. The cLBR for the ‘waiting before IVF’ and the ‘immediate’ strategies were similar. Further studies are needed to better characterize couples affected by unexplained infertility in order to individualize treatment strategies.

Unexplained infertility categorization based on female laparoscopy and total motile sperm count, and its impact on cumulative live-births after one in-vitro fertilization cycle. A retrospective cohort study involving 721 cycles

PURPOSE

To determine how subcategorizing unexplained infertility based on female laparoscopy and total-motile-sperm-count assessment would impact cumulative live-births after one in-vitro fertilization (IVF) cycle.

METHODS

Seven hundred twenty one IVF cycles from Jan 2014-April 2019 performed at a single-center were retrospectively analyzed. Couples with unexplained infertility having normal uterine and endometrial morphology were subcategorized into three cohorts, UI (1): those with no tuboperitoneal pathology on laparoscopy and total-motile-sperm-count (TMSC) ≧20 million: n = 103; UI (2): tuboperitoneal pathology on laparoscopy or TMSC <20 million, n = 86; and UI(3): tuboperitoneal status not known: n = 114. Controls were severe male factor, bilateral tubal block, and grade 3/4 endometriosis: n = 418. Primary Outcome was cumulative-live-birth-per-initiated-IVF cycle (CLBR). Odds ratio for live-births were adjusted for confounding factors.

RESULTS

The CLBR in UI1 cohort was significantly lower than controls (29.1% vs 39; OR = 0.62; 95%CI = 0.39-0.98; P = .04); but similar in UI2 and UI3 vs. controls. (37.2% vs 39.95%; OR = 0.89, 95%CI = 0.55-1.44; P = .89) and (38.6% vs 39.95%; OR = 0.98, 95%CI = 0.64-1.55; P = .98). After adjusting for age, infertility duration, past live-births, and AMH, the adjusted odds for CLBR in UI1 was 0.48 (95%CI = 0.28-0.82; P = .007).

CONCLUSIONS

Unexplained infertility when defined after a normal laparoscopy and TMSC significantly lowered cumulative-live-births-per-initiated-IVF cycle when compared with traditional diagnosis of tubal, endometriosis, or male factor infertility. In UI subcategory with abnormal laparoscopy or TMSC, CLBR remained unaffected. This information could be useful for counseling couples prior to IVF. Large-scale prospective studies are needed to confirm this observation.

Iodine and fertility: do we know enough?

Iodine is a vital micronutrient and its importance in thyroid function is well established. However, abnormalities in iodine intake may also have other effects. In particular, iodine is taken up avidly by the ovary and endometrium. Iodine deficiency is associated with reduced fertility. The use of high iodine concentration contrast media has recently been shown to improve conception rates in couples with unexplained infertility (UI). We hypothesize that this improvement could be related to the iodine excess and mechanisms independent of its action on thyroid. In this article, the metabolism of iodine and its potential role in fertility will be discussed, including the impact of both iodine deficiency and excess states and the importance of iodine in normal fetal development. This will include insights from animal studies on the effect of iodine in the uterine and ovarian structural environment, hormonal milieu and immunological factors affecting implantation. We speculate that iodine may well have a role as a potential therapy for UI.

The Role of Oocyte Quality in Explaining "Unexplained" Infertility

Infertility is described as unexplained when pregnancy does not occur despite ovulation, patent Fallopian tubes, and normal semen parameters. Oocyte developmental competence (or quality) is rate-limiting for pregnancy success as oocytes provide virtually all the cellular building blocks including mitochondria required during embryogenesis. However, available tests estimate oocyte numbers (anti-Müllerian hormone, follicle-stimulating hormone and antral follicle count) and ovulation (luteal phase serum progesterone) but not the third, and most pivotal, oocyte-specific parameter, quality. Severe depletion of the follicular reserve manifests as premature ovarian insufficiency and is an obvious cause of anovulation with overt symptoms and clear diagnostic criteria. In contrast, there are no biomarkers of poor oocyte quality other than through in vitro fertilization when readouts of oocyte quality such as preimplantation embryo development can be assessed. The most common cause of poor oocyte quality is natural aging, which is strongly tied to reduced oocyte mitochondrial efficiency and increased oxidative stress. In younger women, quality may also be impaired due to accelerated aging or sporadic genetic mutations which cause severe defects during oocyte and embryo development. Thus, poor oocyte quality often provides an explanation for infertility, but because it cannot be measured using conventional tests, many cases of infertility are often incorrectly labeled "unexplained." Since female age remains the best predictor of oocyte quality, age over 37 years should be considered an independent diagnostic criterion.

Does Laparoscopy and Hysteroscopy Have a Place in the Diagnosis of Unexplained Infertility?

The standard fertility workup includes assessment of ovulation, semen analysis, and evaluation of tubal patency. If the fertility workup is found to be normal, a diagnosis of unexplained infertility is made. The role of laparoscopy in fertility workup has been a matter of debate. The current review presents the evidence for and against laparoscopy and hysteroscopy during fertility workup and subsequently prior to fertility treatment. After appraising the literature, we found the role of diagnostic laparoscopy in fertility workup is limited and is dependent on factors like prevalence of pelvic infection, setting, and availability of expertise. Moreover, whenever a laparoscopy is planned as a part of the fertility workup, the preparation should include ability to carry out simultaneous therapeutic intervention to maximize the benefit. Similarly, the routine use of hysteroscopy in women with unexplained infertility cannot be recommended. There is a need to investigate the impact of choice of tubal test on chances of spontaneous conception and treatment outcomes in women with unexplained infertility. Our future research agenda should also include high-quality multicenter randomized trials assessing the cost-effectiveness of screening and operative hysteroscopy prior to intrauterine insemination or in vitro fertilization.

How and Why to Define Unexplained Infertility?

Unexplained infertility represents up to 30% of all cases of infertility. It is a diagnosis of exclusion, where no cause for infertility may be identified in the investigation of the couple, be it anovulation, fallopian tube blockage, or severe male factor. Unexplained infertility therefore cannot be considered a diagnosis to which a specific treatment is directed, rather that it indicates a failure to reach a diagnosis of the true cause of infertility. In this review, we explore the evidence base and potential limitations of the current routine infertility assessment. We also aim to highlight the importance of considering the prognosis of each individual couple through the process of assessment and propose a reconsidered approach to treatment, targeted to the prognosis rather than the diagnosis. Ultimately, a better understanding of the mechanisms of infertility will reduce the number of couples diagnosed with "unexplained" infertility.

Special characteristics, reproductive, and clinical profile of women with unexplained infertility versus other causes of infertility: a comparative study

PURPOSE

To investigate whether women with unexplained infertility (UI) demonstrate different demographic and IVF characteristics compared to those with other causes of infertility.

METHODS

Data on 245 couples that underwent a total of 413 IVF/ICSI cycles were analyzed (UI 114 cycles, 73 women; anovulation (PCO/PCOS) 83 cycles, 51 women; tubal factor 85 cycles, 47 women; male factor 131 cycles, 74 women). Features of UI were compared versus other infertility groups, after adjustment for multiple comparisons. Generalized least squares (GLS) and random-effects logistic regression analysis were also performed.

RESULTS

Live birth rates, consisting of the primary outcome, were similar in all compared infertility groups. Compared to male infertility, UI was associated with woman's older age at cycle, lower body mass index (BMI), and higher follicle-stimulating hormone (FSH). Compared to tubal infertility, UI was linked to lower endometrial thickness at oocyte retrieval and lower BMI; compared to anovulatory infertility related to PCO/PCOS, UI was linked to woman's older age, more frequent smoking, and poorer ovarian reserve tests (FSH and antral follicle count). After adjustment for other types of infertility, woman's age, age at menarche, and FSH levels, anovulatory infertility presented with higher odds of clinical pregnancy compared to UI (adjusted OR = 2.13, 95% C: 1.01-4.52).

CONCLUSIONS

Infertile women with UI undergoing assisted reproduction demonstrate different demographic and clinical characteristics compared to those of other causes of infertility, albeit live birth rates are similar.

Biochemistry of infertility

Infertility affects approximately 186 million people worldwide and 8-12% of couples of reproductive age. Therefore, a comprehensive diagnostic evaluation of infertility is crucial to achieving improvements in targeted prevention and treatment outcomes. The aim of this review is to explore the biochemistry of infertility in order to properly diagnose and treat infertile couples. Recent studies indicate that routine measurement of biochemical parameters reflecting thyroid dysfunction, immunological disorders, autoimmune mechanisms, insulin resistance and malabsorption of selected micro- and macronutrients are required to assess infertility. Due to the complexity of this approach, algorithmic protocols that integrate these biochemical parameters in a dynamic test environment are necessary to provide a more comprehensive diagnostic assessment and more effective treatment strategy for infertile couples.

Predictive serum markers for unexplained infertility in child-bearing aged women

PROBLEM

Unexplained infertility (UI) represents about 25%-40% of all infertility and is a formidable obstacle for successful pregnancy for child-bearing aged women. However, up to now, there is no reliable method to predict this condition with high accuracy, thereby hindering early management of this condition.

METHOD OF STUDY

Our prospective study consists of 84 child-bearing aged women that were clinically diagnosed UI. Forty-four matched healthy fertility (HF) women were served as controls. We examined the profiles of 25 hormones and cytokines that were likely related to pathogeneses and molecular pathways involved in UI with the technique of protein array. The samples were randomly stratified 7:3 into a training set and a testing set. We used the SMOTEboost model with 10 serum proteins in a clinical verification study to identify UI cases.

RESULTS

The predictor had an area under the receiver operating characteristic curve (AUC) of 0.788 with 24 serum protein features. The predictive performance in terms of AUC of the model with the top 10 important serum proteins in the clinical verification study to classify UI cases was 0.809. Three most significantly differentially expressed proteins (DEPs) were prolactin, monocyte chemotactic protein-1 (MCP-1), and leptin.

CONCLUSION

Examination of serum-based protein profile changes could help to identify child-bearing aged women at risk of UI. This would enable early detection and facilitate development of clinical strategies to treat UI and guide their planned parenthood. It may also give clues to pathogeneses of the condition of test subjects.

Aberrant Expression of lncRNA ( HOXA11-AS1) and Homeobox A ( HOXA9, HOXA10, HOXA11, and HOXA13) Genes in Infertile Women With Endometriosis

This study aimed to study the expression of homeobox (HOX)A11-AS1 ( HOXA11 antisense RNA) long noncoding RNA (lncRNA) and the expression of homeobox A ( HOXA9, HOXA10, HOXA11, and HOXA13) genes in the eutopic (EU) and ectopic (EC) endometria of women with peritoneal endometriosis. A total of 30 women undergoing laparoscopic surgery for peritoneal endometriosis and 15 infertile women without endometriosis were enrolled in this study. Peritoneal EC tissue samples were obtained through surgery. The EU tissues were obtained by curettage. The EC and EU lncRNA and messenger RNA (mRNA) expression levels were measured using real-time reverse transcriptase-polymerase chain reaction. The HOXA11-AS1 lncRNA and HOXA9, HOXA10, HOXA11, and HOXA13 mRNA were expressed at significantly lower levels in the EU than in the EC, that is, in women with peritoneal endometriosis ( P < .05). The expression levels of HOXA10 and HOXA11 in the EU were significantly lower in women with peritoneal endometriosis compared to the control group participants ( P < .05), whereas the levels of lncRNA ( HOXA11-AS1), HOXA9, and HOXA13 did not differ significantly between the 2 patient groups ( P > .05). In conclusion, the study findings suggest that HOXA11-AS1 lncRNA may play a role in the development of peritoneal endometriosis, but HOXA11-AS1 may not influence endometrial receptivity in endometriosis-associated infertility.

Cardiovascular risk may be increased in women with unexplained infertility

Objective

Growing evidence suggests that increased cardiovascular disease (CVD) risk is associated with female infertility caused by conditions such as polycystic ovarian disease, obesity, thyroid dysfunction, and endometriosis. The aim of this study was to evaluate whether any relationship exists between CVD and unexplained infertility.

Methods

Sixty-five women with unexplained infertility and 65 fertile controls were enrolled in the study. CVD risk markers such as low-density lipoprotein (LDL), high-density lipoprotein (HDL), total cholesterol (TC), triglycerides (TG), insulin resistance (defined by the homeostasis model assessment ratio), and high-sensitivity C-reactive protein (hs-CRP) were assessed.

Results

TG, TC, LDL, and hs-CRP levels were higher and HDL levels were lower in patients with unexplained infertility than in fertile controls (p<0.05 for all). Positive associations were found between unexplained infertility and TG, TC, LDL, and hs-CRP levels, and a negative correlation was found for HDL (p<0.05 for all). Multivariate logistic regression analysis showed that TG, HDL, and hs-CRP were independent variables associated with unexplained infertility.

Conclusion

Our study showed that women with unexplained infertility had an atherogenic lipid profile and elevated hs-CRP levels, suggesting a higher risk of developing CVD in the future. Further studies with larger groups are needed to investigate the nature of this link.

Immune Aspects of Female Infertility

Immune infertility, in terms of reproductive failure, has become a serious health issue involving approximately 1 out of 5 couples at reproductive age. Semen that is defined as a complex fluid containing sperm, cellular vesicles and other cells and components, could sensitize the female genital tract. The immune rejection of male semen in the female reproductive tract is explained as the failure of natural tolerance leading to local and/or systemic immune response. Present active immune mechanism may induce high levels of anti-seminal/sperm antibodies. It has already been proven that iso-immunization is associated with infertility. Comprehensive studies with regards to the identification of antibody-targets and the determination of specific antibody class contribute to the development of effective immuno-therapy and, on the other hand, potential immuno-contraception, and then of course to complex patient diagnosis. This review summarizes the aspects of female immune infertility.

The low expression of leukemia inhibitory factor in endometrium: possible relevant to unexplained infertility with multiple implantation failures

Unexplained infertility affects 25% of infertile couples. Cytokines and growth factors have been suggested to play an important role in the initial process of successful implantation in humans and failures in their production may be a cause of unexplained infertility. Leukemia inhibitory factor (LIF) and Interleukin-6 (IL-6) have demonstrated their importance in implantation in both animal and human studies. Lower expression of LIF is found in proliferative phase and maximal expression is found in secretory phase of the menstrual cycle. Lower expression of LIF is also found in secretory phase endometrium in patients with infertility. However, studies investigating whether the levels of LIF in proliferative phase are associated with multiple implantation failures (MIFs) are limited. 30 Endometrial biopsies in proliferative phase from unexplained infertile women with MIF with normal hormone levels were collected. The expression of LIF, IL-6 and its receptor gp130 were measured by immunohistochemistry and western blotting. Moderate expression of LIF in the proliferative phase and high expression of LIF in the secretory phase were found in fertile women. However, lower expression of LIF was found in unexplained infertile women with MIF compared to fertile women. There was no difference in endometrial IL-6 and gp130 expression between unexplained infertile women with MIF and fertile women. LIF expression is independent of the process of embryo and dependent partially on the maternal sex hormone levels. Our data suggest that the initial lower expression of LIF in proliferative phase may be one of the causes for multiple failure of implantation.

The psychological profile and affective response of women diagnosed with unexplained infertility undergoing in vitro fertilization

It has been hypothesized that unexplained infertility may be related to specific personality and coping styles. We studied two groups of women with explained infertility (EIF, n = 63) and unexplained infertility (UIF, n = 42) undergoing an in vitro fertilization (IVF) cycle. Women completed personality and coping style questionnaires prior to the onset of the cycle, and state depression and anxiety scales before and at two additional time points during the cycle. Almost no in-between group differences were found at any of the measured time points in regards to the Minnesota Multiphasic Personality Inventory-2 validity and clinical scales, Illness Cognitions and Life Orientation Test, or for the situational measures. The few differences found suggest a more adaptive, better coping, and functioning defensive system in women with EIF. In conclusion, we did not find any clinically significant personality differences or differences in depression or anxiety levels between women with EIF and UIF during an IVF cycle. Minor differences found are probably a reaction to the ambiguous medical situation with its uncertain prognosis, amplifying certain traits which are not specific to one psychological structure but rather to the common experience shared by the group. The results of this study do not support the possibility that personality traits are involved in the pathophysiology of unexplained infertility.

Unexplained infertility: association with inherited thrombophilia

INTRODUCTION

Unexplained infertility represents one of the most common diagnoses in fertility care. Attention is being paid to the association between inherited thrombophilia and infertility causes. In this study we investigated the prevalence of inherited thrombophilia according to infertility causes.

MATERIALS AND METHODS

We studied Prothrombin gene G20210A mutation, Factor V Leiden, deficiencies in protein S and C and antithrombin in 930 Caucasian infertile women referred to Fertility Center of the Department of Sciences for Woman and Child's Health, University of Florence, of whom 230 with unexplained, 195 female and 283 male infertility, and in 240 women who have conceived naturally without hormonal stimulation therapy.

RESULTS

A significant relationship between inherited thrombophilia [OR 95%CI 1.97 (1.05-3.68), p = 0.03] and unexplained infertility was observed, whereas no association between thrombophilia and female and male infertility was found. Significantly higher prevalence of prothrombin gene mutation in unexplained infertile women in comparison to that observed in fertile women was observed (5.7% vs 2.1% p = 0.04); the prevalence of the other thrombophilia determinants was higher, even if not significantly, in the unexplained infertile group.

CONCLUSIONS

This study demonstrates the relationship between inherited thrombophilia and unexplained infertility, thus suggesting the contribution of genetic components in modulating unexplained infertility, behind anovulation, male and tubal factor.