Heavy metals and diminished ovarian reserve: single-exposure and mixture analyses amongst women consulting in French fertility centres.

RESEARCH QUESTION: Do heavy metals affect the risk of diminished ovarian reserve (DOR) in women of reproductive age? DESIGN: A total of 139 cases and 153 controls were included between 2016 and 2020. The participants were aged between 18 and 40 years and attended consultations for couple infertility in one of four fertility centres in western France. Cases of DOR were defined as women with an antral follicle count less than 7, anti-Müllerian hormone levels 1.1 ng/ml or less, or both. Controls were frequency matched on age groups and centres, and were women with normal ovarian reserve evaluations, no malformations and menstrual cycles between 26 and 35 days. Heavy metals (lead, mercury, cadmium and chromium) were measured in whole blood at inclusion. Single-exposure associations were examined with multivariable logistic regressions adjusted on potential confounders. Mixture effects were investigated with quantile g-computation and Bayesian kernel machine regression (BKMR). RESULTS: Chromium as a continuous exposure was significantly associated with DOR in unadjusted models (OR 2.07, 95% CI 1.04 to 4.13) but the association was no longer significant when confounders were controlled for (adjusted OR 2.75, 95% CI 0.88 to 8.60). Similarly, a statistically significant association was observed for the unadjusted second tercile of cadmium exposure (OR 1.87, 95% CI 1.06 to 3.30); however, this association was no longer statistically significant after adjustment. None of the other associations tested were statistically significant. Quantile g-computation and BKMR both yielded no significant change of risk of DOR for the mixture of metals, with no evidence of interaction. CONCLUSIONS: Weak signals that some heavy metals could be associated with DOR were detected. These findings should be replicated in other studies.

Blood anti-Müllerian hormone is a possible determinant of recurrent early miscarriage, yet not conclusive in predicting a further miscarriage.

RESEARCH QUESTION: Is blood anti-Müllerian hormone (AMH) concentration a strong determinant of unexplained recurrent early miscarriage (REM)? DESIGN: In the first part of the study, AMH concentrations measured using an Immunotech ELISA Kit were compared between 188 unselected (mostly fertile) women consecutively referred for three or more miscarriages in the first trimester of pregnancy and 376 age-matched parous women without pregnancy loss. Cases and controls were previously enrolled in an incident case-control study on thrombophilic mutations. Blood samples were collected >2 months after any recognized obstetric event or hormonal treatment. In the second part of the study, a prospective 2-year follow-up of cases was performed. RESULTS: When considering all women irrespective of age, AMH concentration did not significantly differ between cases and controls. However, in the subgroup ≥25 years old (176 cases versus 358 controls of ∼33.5 years), the cases had significantly lower AMH concentrations than the controls (median [interquartile range]: 2.8 [1.4-4.7] versus 3.25 [1.7-5.5], P = 0.046) and the proportion of cases with an AMH concentration <1 ng/ml was significantly higher (17.6% versus 10.6%; odds ratio 1.80; 95% confidence interval 1.07-3.00, P = 0.028). With regard to the subsequent pregnancy, AMH concentration was not correlated with either the conception delay or the miscarriage occurrence. However, increased age and number of previous miscarriages were significantly predictive of a subsequent miscarriage (P = 0.046 and 0.03, respectively). CONCLUSION: An altered ovarian reserve is a possible determinant of unexplained REM. However, AMH blood concentration predicts neither the delay nor the outcome of a subsequent pregnancy.

Can Ratios Between Prognostic Factors Predict the Clinical Pregnancy Rate in an IVF/ICSI Program with a GnRH Agonist-FSH/hMG Protocol? An Assessment of 2421 Embryo Transfers, and a Review of the Literature.

None of the models developed in in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) is sufficiently good predictors of pregnancy. The aim of this study was to determine whether ratios between prognostic factors could predict the clinical pregnancy rate in IVF/ICSI. We analyzed IVF/ICSI cycles (based on long GnRH agonist-FSH protocols) at two ART centers (the second to validate externally the data). The ratios studied were (i) the total FSH dose divided by the serum estradiol level on the hCG trigger day, (ii) the total FSH dose divided by the number of mature oocytes, (iii) the serum estradiol level on the trigger day divided by the number of mature oocytes, (iv) the serum estradiol level on the trigger day divided by the endometrial thickness on the trigger day, (v) the serum estradiol level on the trigger day divided by the number of mature oocytes and then by the number of grade 1 or 2 embryos obtained, and (vi) the serum estradiol level on the trigger day divided by the endometrial thickness on the trigger day and then by the number of grade 1 or 2 embryos obtained. The analysis covered 2421 IVF/ICSI cycles with an embryo transfer, leading to 753 clinical pregnancies (31.1% per transfer). Four ratios were significantly predictive in both centers; their discriminant power remained moderate (area under the receiver operating characteristic curve between 0.574 and 0.610). In contrast, the models' calibration was excellent (coefficients: 0.943-0.978; p < 0.001). Our ratios were no better than existing models in IVF/ICSI programs. In fact, a strongly discriminant predictive model will be probably never be obtained, given the many factors that influence the occurrence of a pregnancy.

The first assessment of soluble CD146 in women with unexplained pregnancy loss. A new insight?

The mechanisms responsible for pregnancy loss have not all been elucidated. CD146 is a cell adhesion molecule involved in the control of both endothelium integrity and intermediate trophoblast invasiveness, two potential key features in the pathogenesis of pregnancy loss. As CD146 is detectable as a soluble form in the plasma (sCD146), we investigated sCD146 plasma levels in women with a history of pregnancy loss. We conducted a paired case-control study to compare sCD146 plasma levels in 100 women with unexplained pregnancy losses (2 or more consecutive losses at or before 21 weeks of gestation, or at least one later loss) and in 100 age-matched control women (no pregnancy loss and at least one living child). The sCD146 concentrations were determined at least 2 months after the last obstetrical event. Patients and controls were comparable regarding thrombophilia. Among the patients, 83 women experienced early pregnancy losses (average of 3 losses, mean gestation of 6.6 weeks) and 22 women suffered at least one late pregnancy loss. We found significantly higher sCD146 plasma levels in the 100 patients compared to age matched control women (p < 0.001). The sCD146 plasma levels did not correlate with the number of pregnancy losses nor with the mean gestation time. Alterations in sCD 146 plasma levels could be related to endothelial dysfunction associated to defective endovascular trophoblast invasiveness. Additional studies should explore whether sCD146 assessment could provide diagnostic and prognostic information with a view to screening and thus managing women with unexplained pregnancy loss.