Vitamin D and miscarriage: a systematic review and meta-analysis

Effects of MTHFR C677T polymorphism on homocysteine and vitamin D in women with polycystic ovary syndrome

OBJECTIVES

To evaluate the correlation between serum vitamin D, homocysteine and the methylene tetrahydrofolate reductase (MTHFR) C677T polymorphism in women with polycystic ovary syndrome (PCOS). Study design We retrospectively compared the serum homocysteine and vitamin D levels and the MTHFR C677T polymorphism in 104 PCOS patients and 104 controls. Parameters related to PCOS were statistically analysed.

RESULTS

Comparative analysis revealed that women with PCOS had significantly greater serum homocysteine levels (P = 0.002) and lower vitamin D concentrations (P = 0.040) than controls. The distribution frequency of the MTHFR C677T genotype did not significantly differ between the PCOS group and the control group. (P > 0.05). In the PCOS group, the serum level of homocysteine in the TT group was significantly greater than that in the CT (P = 0.003) and CC (P = 0.002) groups and the level of vitamin D in the TT group was significantly less than that in the CC (P < 0.001) and CT (P = 0.172) groups. The results were similar when the PCOS and control groups were divided according to whether they had insulin resistance. Vitamin D levels were significantly negatively correlated with homocysteine levels in all PCOS patients (r = -0.281, P = 0.004), similarly, vitamin D levels were negatively correlated with homocysteine levels in the CC, CT and TT of PCOS patients. According to multivariate analysis, vitamin D concentration was an independent risk factor for hyperhomocysteinaemia (adjusted OR 1.372, 95 % CI: 1.100-1.712).

CONCLUSIONS

No significant differences were found in the distributions of MTHFR C677T genotypes between the PCOS and control groups but these genotypes affected the patients' serum homocysteine and vitamin D concentrations. Women with the TT genotype have significantly lower vitamin D levels and higher homocysteine levels than women with the CC and CT genotypes. However, because of the limitations of this investigation, large-sample, high-quality prospective studies are needed to further verify these results in the future.

Evaluation of Recurrent Pregnancy Loss

Recurrent pregnancy loss (RPL) affects approximately 5% of couples. Although RPL definitions vary across professional societies, an evaluation after a second clinically recognized first-trimester pregnancy loss is recommended. Good quality evidence links parental chromosomal rearrangements, uterine anomalies, and antiphospholipid syndrome (APS) to RPL. In contrast, the relationship between RPL and other endocrine, hematologic, and immunologic disorders or environmental exposures is less clear. Anticoagulant therapy and low-dose aspirin are recommended for patients with RPL who have also been diagnosed with APS. Vaginal progesterone supplementation may be considered in patients experiencing vaginal bleeding during the first trimester. Surgical correction may be considered for patients with RPL in whom a uterine anomaly is identified. Evaluation and management of additional comorbidities should be guided by the patient's history rather than solely based on the diagnosis of RPL, with the goal of improving overall health to reduce complications in the event of pregnancy. Most people with RPL, including those without identifiable risk factors, are expected to achieve a live birth within 5 years from the initial evaluation. Nevertheless, clinicians should be sensitive to the psychological needs of individuals with this condition and provide compassionate and supportive care across all stages.

Effect of anti-thyroid antibodies on recurrent miscarriage: A meta-analysis

SETTING

Previous studies addressed the association between anti-thyroid antibodies and recurrent miscarriage (RM), however, the role of anti-thyroid antibodies in RM patients is debatable.

OBJECTIVES

Therefore, we conducted this meta-analysis and the aim of this current study was to assess whether anti-thyroid peroxidase (anti-TPO) and/or anti-thyroglobulin (anti-TG) antibody positivity was associated with RM.

DESIGN

A meta-analysis was conducted.

PARTICIPANTS

Recurrent miscarriage patients.

METHODS

STATA 12.0 software were applied to compute odds ratios (ORs)/relative risks (RRs) and 95% CIs regarding association between anti-TPO and anti-TG antibodies and the prevalence of RM.

RESULTS

N = 28 studies (8875 participants) explored effect of anti-thyroid antibodies on RM. Analysis of the 28 studies revealed significant association between anti-TPO, anti-TG antibodies and the prevalence of RM with a random effects model (OR/RR = 2.02; 95% CI: 1.63-2.51, p < 0.001; I2 = 44.3%, p value for Q test = 0.004). Analysis of the 20 studies revealed significant association between anti-TPO antibodies and the prevalence of RM with a random effects model (OR/RR = 1.59; 95% CI: 1.25-2.03, p < 0.001; I2 = 43.1%, p value for Q test = 0.022). Analysis of the 14 studies revealed significant association between anti-TG antibodies and the prevalence of RM with a random effects model (OR/RR = 2.25; 95% CI: 1.56-3.23, p < 0.001; I2 = 49.2%, p value for Q test = 0.019).

CONCLUSIONS

Based on the currently available analysis, our findings suggest that women with anti-TPO and/or anti-TG antibodies have a higher risk of RM than that in negative antibody women. Further investigation is needed to better clarify the exact role of the anti-thyroid antibodies in RM and whether treatment is of benefit.

LIMITATIONS

First, differences from various detection methods and reagents used in different studies may affect the diagnostic interpretation of anti-thyroid antibodies, which might influence the accuracy of this meta-analysis. Second, positive anti-thyroid antibodies seem likely to be part of a more general disorder of maternal immune system, due to restrictions of funding and condition, a complete autoantibody screening investigation is hardly to conduct in all participants, and this could be a possible limitation of all included studies. Third, there is no mention of thyroxine therapy on RM, making the meta-analysis even more limited.

Nutritional supplements and IVF: an evidence-based approach

Many women undergoing IVF take supplements during treatment. The purpose of this review was to systematically review these nutritional supplements. The therapies studied are dehydroepiandrosterone (DHEA), melatonin, co-enzyme Q10 (CoQ1O), carnitine, selenium, vitamin D, myo-inositol, omega-3, Chinese herbs and dietary interventions. A literature search up to May 2023 was undertaken. The data suggest that a simple nutritional approach would be to adopt a Mediterranean diet. With regards to supplements to treat a potential poor ovarian response to ovarian stimulation, starting DHEA and COQ-10 before cycle commencement is better than control therapies. Furthermore, medication with CoQ10 may have some merit, although it is unclear whether its place is for older women, for those with a poor response to ovarian stimulation or for poor embryonic development. There appears a benefit for some IVF outcomes for the use of melatonin, although it is unclear what group of patients would derive the benefit and the appropriate dosing regimen. For women with polycystic ovary syndrome, there may be a benefit to the use of myo-inositol, although again the dosing regimen is unclear. Furthermore, the place of vitamin D supplementation has yet to be clarified, and supplementation with omega-3 free fatty acids may lead to improvements in clinical and embryological IVF outcomes.

No evidence of a causal relationship between miscarriage and 25-hydroxyvitamin D: a Mendelian randomization study

STUDY QUESTION

Is there a causal relationship between 25-hydroxyvitamin D (25OHD) and miscarriage?

SUMMARY ANSWER

In this study, little evidence of a causal relationship was found between low serum 25OHD concentration or vitamin D deficiency and the risk of miscarriages.

WHAT IS KNOWN ALREADY

Associations between low vitamin D levels and increased risk of miscarriage have been reported, but causality is unclear.

STUDY DESIGN SIZE DURATION

The latest and largest genome-wide association studies (GWAS) for serum 25OHD concentration (n = 417 580), vitamin D deficiency (426 cases and 354 812 controls), miscarriage (16 906 cases and 149 622 controls), and the number of miscarriages (n = 78 700) were used to explore the causal association between serum vitamin D levels and miscarriage by two-sample Mendelian randomization analysis.

PARTICIPANTS/MATERIALS SETTING METHODS

This study was based on summary GWAS results from the FinnGen database and the UK Biobank. The random-effect inverse-variance weighted method was regarded as the primary analysis; MR-Egger, weighted median, weighted mode, simple mode, and MR-pleiotropy residual sum and outlier (MR-PRESSO) were further employed as complementary methods. MR-Egger intercept analysis and MR-PRESSO were employed to test pleiotropy, and Cochran's Q statistic and leave-one-out sensitivity analysis were used to determine the heterogeneity and robustness of the overall estimates, respectively.

MAIN RESULTS AND THE ROLE OF CHANCE

There was insufficient evidence of causal associations between serum 25OHD concentration and miscarriage (odds ratio (OR) = 0.995, 95% CI: 0.888 to 1.114, P = 0.927), or the number of miscarriages (β = -0.004, 95% CI: -0.040 to 0.032, P = 0.829). Furthermore, little evidence of causality between genetically determined vitamin D deficiency to miscarriage (OR = 0.993, 95% CI: 0.966 to 1.021, P = 0.624), or the number of miscarriages (β = 0.001, 95% CI: -0.009 to 0.011, P = 0.828), was observed. The results of the sensitivity analysis were robust, and no significant heterogeneity or horizontal pleiotropy was found.

LIMITATIONS REASONS FOR CAUTION

This study is limited by the absence of female-specific GWAS data and the limited amount of GWAS data available for this study, as well as the need for caution in generalizing the findings to non-European ethnic groups.

WIDER IMPLICATIONS OF THE FINDINGS

These findings enhance the current understanding of the intricate association between vitamin D and pregnancy outcomes, challenging prevailing beliefs regarding the strong association with miscarriage. The results provide a special perspective that may prompt further exploration and potentially offer insights for guiding future research and informing clinical guidelines pertaining to the management of miscarriage.

STUDY FUNDING/COMPETING INTERESTS

This project was supported by the Hubei Provincial Natural Science Foundation Program General Surface Project (2022CFB200), the Key Research & Developmental Program of of Hubei Province (2022BCA042), the Fundamental Research Funds for the Central Universities (2042022gf0007, 2042022kf1210), and the Interdisciplinary Innovative Talents Foundation from Renmin Hospital of Wuhan University (JCRCWL-2022-001, JCRCYG-2022-009). All authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

CPY27B1-related vitamin D deficiency contributes to the impaired function of CD4+T cells in Recurrent spontaneous miscarriage

The study aimed to explore the relationship between the expression of cytochrome P450 family 27 subfamily B member 1 (CYP27B1), vitamin D, and impaired T cell subsets in recurrent spontaneous miscarriage (RSM). A Total of 779 healthy women of childbearing age and 1031 women with a history of RSM were involved in this study. The results of flow cytometry showed that the proportion of Tregs was higher in healthy women than in the women with RSM. For cytokines, the levels of interleukin-17 (IL-17) and interferon-gamma (IFN-γ) were significantly higher in RSM patients than in healthy women, while IL-10 was notably lower in RSM patients. Furthermore, compared to healthy individuals, RSM patients had lower levels of serum 25(OH)D detected by chemiluminescence. The frequency of Tregs was negatively correlated with 25(OH)D. Specifically, for every 10 ng/ml increase in 25(OH)D, the percentage of Tregs increased by 0.58 as calculated. IL-17 and IFN-γ were inversely correlated with 25(OH)D, while the serum interleukin-10 (IL-10) level was positively correlated with 25(OH)D. CYP27B1 was found to be expressed in both cytotrophoblast and extracellular villi trophoblast cells. However, reduced expression of CYP27B1 was observed in the placenta with RSM. Notably, the level of 25(OH)D increased in the supernatant of CYP27B1 knockdown BeWo compared to normal cells, while human chorionic gonadotropin (hCG) was significantly reduced. The hCG secretion of CYP27B1 KO BeWo cells was partially restored after 1,25(OH)2D3 supplementation. In addition, 1,25(OH)2D3 treatment could induce more CD4+ T cells to convert to Foxp3+iTreg, which in turn inhibited the secretion of IL-17, IFN-γ. In summary, this research unveiled a connection between reduced CYP27B1 and vitamin D deficiency in RSM. Our study underscores the potential benefits of vitamin D treatment supplementation in the context of RSM. However, it is important to note that further research is imperative to validate these observations.

Improving access, understanding, and dignity during miscarriage recovery in British Columbia, Canada: A patient-oriented research study

BACKGROUND

Approximately 15%-25% of clinical pregnancies end in miscarriage, with more than 15,000 miscarriages occurring annually in British Columbia, Canada. Despite the significant rates of loss, research and health care services for pregnancy loss remain scarce in British Columbia.

OBJECTIVES

This study aimed to (1) aid miscarriage recovery through the identification and sharing of equitable pregnancy loss care practices and supports and (2) present policy recommendations to improve prenatal care guidelines and employment standards for pregnancy loss.

DESIGN

This research took a patient-oriented methodological approach alongside people with lived/living experience(s) of miscarriage recovery in British Columbia to evaluate access to health care during pregnancy loss, societal understanding of miscarriage, and treatment options that foreground dignity.

METHODS

The mixed-methods design of this research included policy research on prenatal care guidelines, policy research on provincial and territorial employment legislation for bereavement leave, semi-structured interviews (n = 27), and a discovery action dialogue (n = 4).

RESULTS

The findings of this research demonstrate the need for improved prenatal care guidelines for early pregnancy loss, follow-up care after a miscarriage, mental health screening and supports, and bereavement leave legislation.

CONCLUSION

This article includes recommendations to improve equitable access to pregnancy loss care, bereavement leave legislation, and future research in this area.

Management strategies following implantation failure of euploid embryos

Background

Euploid blastocyst implantation failure may result from embryonic factors undetectable by preimplantation genetic testing for aneuploidy (PGT-A); however, various nonembryonic factors can also intricately interfere with implantation. This review seeks to clarify evidence-based testing and treatments for implantation failure after euploid embryo transfer.

Methods

We conducted a review of the literature on implantation failure after euploid embryo transfer or multiple embryo transfer cycles, which mainly included systematic reviews and meta-analyses.

Results

The recommended tests for implantation failure include (1) hysteroscopy, (2) endometrial CD138 immunohistochemistry and bacterial culture, (3) serum 25-hydroxyvitamin D3, and (4) thrombophilia screening. Based on diagnostic findings, the following treatments have been recommended: (1) antibiotics for chronic endometritis, (2) vitamin D replacement, (3) lifestyle modification, and (4) low-dose aspirin starting from the postimplantation period for thrombophilia. Moreover, frozen-thawed single euploid blastocyst transfer using assisted hatching and hyaluronan-enriched transfer medium may support embryo implantation.

Conclusion

To ensure a successful pregnancy in subsequent embryo transfers, simple, inexpensive, and evidence-based tests and treatments should be selected.

A review of the optimization of thyroid function, thrombophilia, immunity and uterine milieu treatment strategy for recurrent implantation failure and recurrent pregnancy loss

Background

Aside from embryonic factors, various factors can intricately interfere with embryo implantation and maintenance of pregnancy, causing recurrent implantation failure (RIF) or recurrent pregnancy loss (RPL). This review focuses the optimization of thyroid function, thrombophilia, immunity, and uterine milieu (OPTIMUM) treatment strategy on RIF and RPL.

Methods

Three studies employing the OPTIMUM treatment strategy for patients with RIF and/or RPL were reviewed.

Results

The OPTIMUM improved pregnancy rates in women with RIF aged <40 years. Among advanced age women, however, no significant differences in pregnancy rates were observed between the control, OPTIMUM, and preimplantation genetic testing for aneuploidy (PGT-A) groups, although pregnancy rates were highest after OPTIMUM + PGT-A. The OPTIMUM reduced miscarriage rates in women with RPL aged <40 years. Among advanced age women, PGT-A, but not the OPTIMUM, contributed to miscarriage prevention. Factors predicting pregnancy success in women with RIF who received the OPTIMUM included thrombophilia and young age. Risk factors for an unsuccessful live birth among women with RPL who received the OPTIMUM included advanced age, infertility, diminished ovarian reserve, and non-ART treatment.

Conclusions

The OPTIMUM can improve pregnancy outcomes in women with RIF/RPL, except for advanced age women with embryonic factor-induced reproductive failure.

Evaluation of serum anti-Müllerian hormone concentrations following treatment with vitamin D in Holstein Friesian heifers

Anti-Müllerian hormone (AMH) levels in the blood of dairy cattle are associated with the count of antral follicles (AFC), ovarian function. Numerous studies, particularly in human medicine, have shown that vitamin D3 (Vit D3) has a positive effect on AMH levels. To our knowledge, the effects of Vit D3 on serum AMH levels in heifers have not been investigated. The goal of the current study was to evaluate the concentrations of serum AMH in dairy heifers following Vit D3 treatment. The study included 20 healthy non-pregnant Holstein Friesian heifers. These animals came to estrus at least once. All heifers received a single intramuscular dosage of 5 million IU Vit D3 (Cholecalciferol). Blood samples were collected from the coccygeal veins of all animals before and after Vit D3 injection (days 7, 14, and 28) for the measurement of AMH and 25(OH)D concentrations. In our analysis, we observed that after exogenous Vit D3 administration, circular 25(OH)D increased constantly (up to day 28 after Vit D3 injection) in all animals. On day 28, AMH concentrations saw a 10% increase in comparison with those measured the day before the Vit D3 injection. However, a comparison of AMH concentrations measured across days did not reveal statistically significant differences between Day 0, 7, 14, and 28 levels (p = .10). Furthermore, no statistical correlation was observed between the pairs (age-AMH) and (weight-AMH). Considering all times, no correlation was found between 25(OH)D and blood AMH levels. These findings demonstrated that exogenous Vit D3 did not affect serum AMH in Holstein Friesian heifers.

Does a history of childbirth impact injury prevalence and mental health in female military members?

The effect of parity status on the prevalence and impact of musculoskeletal injury (MSKi) among female Canadian Armed Forces (CAF) members is unknown. This study aims to identify whether a history of childbirth and pregnancy-related complications are associated with MSKi occurrence among female members of the CAF. From September 2020 to February 2021, data were collected via an online questionnaire that assessed MSKi, reproductive health, and barriers to recruitment and retention in the CAF. Actively serving, female members were included in this analysis stratified by parous (n = 313) or nulliparous (n = 435) status. Descriptive analysis and binary logistic regressions were used to identify prevalence and adjusted odds ratios (aOR) of repetitive strain injuries (RSI), acute injuries, and body regions affected. Covariates included in aOR: age, body mass index, and rank. A p value of <0.05 was considered significant and 95% confidence intervals (CI) were reported. Female members with a history of childbirth were more likely to report an RSI (80.9% vs. 69.9%, OR = 1.57, CI: 1.03 to 2.40), and when stratified by body region, were more likely to have an RSI of the wrist (30.0% vs. 20.5%, aOR = 1.62, CI: 1.09 to 2.40), and foot (39.3% vs. 24.1%, aOR = 1.79, CI: 1.24 to 2.59). When compared to the nulliparous group, parity did not influence prevalence of acute injuries. MSKi and mental health perceptions were different for females who experienced postpartum depression, miscarriage, or preterm birth. Childbirth and pregnancy-related complications impact prevalence of some RSI among female CAF members. Thus, specific health and fitness support may be needed for parous female CAF members.

Interventions to prevent miscarriage

The physical and psychological impact of miscarriage can be devastating. There are many lifestyle and therapeutic interventions that may prevent a miscarriage. In this review, we have outlined the key areas for health optimization to prevent pregnancy loss, drawing on the most up-to-date evidence available. The 3 key areas identified are lifestyle optimization in women, lifestyle optimization in men, and therapeutic interventions. The evidence demonstrates that the treatments to consider are first-trimester progesterone administration, levothyroxine in women with subclinical hypothyroidism, and the combination of aspirin and heparin in women with antiphospholipid antibodies.

Effect of Oral High Molecular Weight Hyaluronic Acid (HMWHA), Alpha Lipoic Acid (ALA), Magnesium, Vitamin B6 and Vitamin D Supplementation in Pregnant Women: A Retrospective Observational Pilot Study

Background-Pregnancy represents a nutritional challenge, since macro- and micronutrients intake can affect mother' health and influence negative outcomes. The aim of this retrospective pilot study is to evidence whether the oral supplementation with high molecular weight hyaluronic acid (HMWHA), in association with alpha lipoic acid (ALA), magnesium, vitamin B6 and vitamin D, in pregnant women, could reduce adverse effects, such as PTB, pelvic pain, contraction and hospitalization. Methods-Data were collected from n = 200 women treated daily with oral supplements of 200 mg HMWHA, 100 mg ALA, 450 mg magnesium, 2.6 mg vitamin B6 and 50 mcg vitamin D (treatment group) and from n = 50 women taking with oral supplements of 400 mg magnesium (control group). In both groups, supplementation started from the 7th gestational week until delivery. Results-Oral treatment with HMWHA, in association with ALA, magnesium, vitamin B6 and vitamin D in pregnant women, significantly reduced adverse events, such as PTB (p < 0.01), pelvic pain and contractions (p < 0.0001), miscarriages (p < 0.05) and admission to ER/hospitalization (p < 0.0001) compared with the control group. Conclusions-Despite HMWHA having been poorly used as a food supplement in pregnant women, our results open a reassuring scenario regarding its oral administration during pregnancy.

Calcifediol in the management of vitamin D deficiency-related skeletal and extraskeletal diseases: overview and clinical cases

As well as being essential for musculoskeletal health, vitamin D is involved in numerous other physiological processes. Poor vitamin D status is linked to a wide range of diseases, including cardiovascular disease, autoimmune conditions, pulmonary disorders and upper respiratory tract infections. While optimal target concentrations of serum 25-hydroxyvitamin D (25(OH)D) for health maintenance or therapeutic purposes are still the subject of debate, there is reasonable agreement that serum 25(OH)D levels <50 nmol/L (20 ng/mL) constitute vitamin D deficiency and that severe deficiency states (serum 25(OH)D levels <25-30 nmol/L ≈ 10-12 ng/mL) should be avoided. Main strategies to maintain or improve vitamin D status are food supplementation and therapeutic use of medicinal forms of vitamin D. In this review, we examine evidence that implicates vitamin D deficiency in diverse conditions in the clinical settings of endocrinology, rheumatology, pneumology and reproductive health. Cholecalciferol (vitamin D3) is the most frequently used vitamin D supplement worldwide, though calcifediol (25-hydroxyvitamin D3) has recently become more widely available. Calcifediol is one step closer than cholecalciferol in the metabolic pathway to biologically active vitamin D. Pharmacokinetic differences between these vitamin D metabolites confer putative advantages for calcifediol in certain clinical situations. The clinical use of calcifediol is explored more closely through case studies, which illustrate its adjunctive role in the treatment of several vitamin D deficiency-related skeletal and extraskeletal diseases.

Association between female circulating heavy metal concentration and abortion: a systematic review and meta-analysis

Objective

This study aimed to evaluate the association between blood heavy metal (zinc (Zn), copper (Cu), lead (Pb), and cadmium (Cd)) concentrations and spontaneous abortion (SA) and recurrent pregnancy loss (RPL) and explore the possible endocrine dysfunction associated with it.

Methods

A literature search was performed in the PubMed, Embase, Cochrane Library, and Web of Science databases up to April 2023. The overall effects were expressed as the standard mean difference (SMD). Subgroup analysis was performed according to the type of abortion (SA or RPL). Stata 16.0 was utilized for data analysis.

Results

Based on the integrated findings, abortion women showed significantly lower Zn (SMD = -1.05, 95% CI: -1.74 to -0.36, p = 0.003) and Cu concentrations (SMD = -1.42, 95% CI: -1.97 to -0.87, p <0.001) and higher Pb (SMD = 1.47, 95% CI: 0.89-2.05, p <0.001) and Cd concentrations (SMD = 1.15, 95% CI: 0.45-1.85, p = 0.001) than normal pregnant women. Subgroup analysis showed that Zn and Cu deficiency and Cd and Pb exposure were significantly (p <0.05) associated with RPL, whereas Cu deficiency and Cd and Pb exposure were significantly (p <0.05) associated with SA.

Conclusion

Zn and Cu deficiencies and Pb and Cd exposure were associated with abortion. Endocrine dysfunction, such as insulin resistance, vitamin D insufficiency, and abnormal thyroid and sex hormone concentrations, is thought to be involved in heavy metal-related abortion.

Recurrent Pregnancy Loss Etiology, Risk Factors, Diagnosis, and Management. Fresh Look into a Full Box

Recurrent pregnancy loss is a complex health challenge with no universally accepted definition. Inconsistency in definitions involves not only the number of spontaneous abortions (two or three) that are accepted for recurrent pregnancy loss but the types of pregnancy and gestational age at miscarriage. Due to the heterogeneity of definitions and criteria applied by international guidelines for recurrent pregnancy loss, the true incidence of recurrent miscarriage, which is reported to range from 1% to 5%, is difficult to estimate. Moreover, the exact etiology of recurrent pregnancy loss remains questionable; thus, it is considered a polyetiological and multifactorial condition with many modifiable and non-modifiable factors involved. Even after thoroughly evaluating recurrent pregnancy loss etiology and risk factors, up to 75% of cases remain unexplained. This review aimed to summarize and critically analyze accumulated knowledge on the etiology, risk factors, relevant diagnostic options, and management approach to recurrent pregnancy loss. The relevance of various factors and their proposed roles in recurrent pregnancy loss pathogenesis remains a matter of discussion. The diagnostic approach and the management largely depend on the etiology and risk factors taken into consideration by a healthcare professional as a cause of recurrent miscarriage for a particular woman or couple. Underestimation of social and health consequences of recurrent pregnancy loss leads to compromised reproductive health and psychological well-being of women after miscarriage. Studies on etiology and risk factors for recurrent pregnancy loss, especially idiopathic, should be continued. The existing international guidelines require updates to assist clinical practice.

Time-to-conception and clinical pregnancy rate with a myo-inositol, probiotics, and micronutrient supplement: secondary outcomes of the NiPPeR randomized trial

OBJECTIVE

To determine whether a combined myo-inositol, probiotics and micronutrient nutritional supplement impacts time-to-natural-conception and clinical pregnancy rates.

DESIGN

Secondary outcomes of a double-blind randomized controlled trial.

SETTING

Community recruitment.

PATIENTS

Women aged 18 to 38 years planning to conceive in the United Kingdom, Singapore, and New Zealand, excluding those with diabetes mellitus or receiving fertility treatment.

INTERVENTION

A standard (control) supplement (folic acid, iron, calcium, iodine, β-carotene), compared with an intervention additionally containing myo-inositol, probiotics, and other micronutrients (vitamins B2, B6, B12, D, zinc).

MAIN OUTCOME MEASURES

Number of days between randomization and estimated date of natural conception of a clinical pregnancy, as well as cumulative pregnancy rates at 3, 6, and 12 months.

RESULTS

Of 1729 women randomized, 1437 (83%; intervention, n=736; control, n=701) provided data. Kaplan-Meier curves of conception were similar between intervention and control groups; the time at which 20% achieved natural conception was 90.5 days (95% confidence interval: 80.7, 103.5) in the intervention group compared with 92.0 days (76.0, 105.1) in the control group. Cox's proportional hazard ratios (HRs) comparing intervention against control for cumulative achievement of pregnancy (adjusted for site, ethnicity, age, body mass index, and gravidity) were similar at 3, 6, and 12 months. Among both study groups combined, overall time-to-conception lengthened with higher preconception body mass index, and was longer in non-White than in White women. Among women who were overweight the intervention shortened time-to-conception compared with control regardless of ethnicity (12-month HR=1.47 [1.07, 2.02], P=.016; 20% conceived by 84.5 vs. 117.0 days) and improved it to that comparable to nonoverweight/nonobese women (20% conceived by 82.1 days). In contrast, among women with obesity, time-to-conception was lengthened with intervention compared with control (12-month HR=0.69 [0.47, 1.00]; P=.053; 20% conceived by 132.7 vs. 108.5 days); an effect predominantly observed in non-White women with obesity.

CONCLUSIONS

Time-to-natural-conception and clinical pregnancy rates within a year were overall similar in women receiving the intervention supplement compared with control. Overweight women had a longer time-to-conception but there was suggestion that the supplement may shorten their time-to-conception to that comparable to the nonoverweight/nonobese women. Further studies are required to confirm this.

CLINICAL TRIAL REGISTRATION NUMBER

clinicaltrials.gov (NCT02509988).

Association of maternal vitamin D status with the risk of preeclampsia

The aim of this study was to examine serum vitamin D concentrations from early pregnancy until delivery in women who did and did not develop preeclampsia. This longitudinal study was carried out in Pune, India. A total of 1154 women with singleton pregnancies were recruited in early pregnancy from two hospitals. Blood samples were collected and stored at four time points across gestation: V1 = 11-14 weeks, V2 = 18-22 weeks, V3 = 26-28 weeks and V4 = at delivery. 108 women who developed preeclampsia (PE) and 216 who did not develop PE (Non-PE) were randomly selected from the remainder. Serum 25-hydroxy vitamin D concentrations (25(OH)D) were estimated in their samples using commercially available ELISA kits. Independent t-tests were used to compare 25(OH)D between PE and non-PE groups. Logistic and linear regressions were used to examine associations of 25(OH)D with the risk of preeclampsia and birth outcomes, respectively, after adjusting for confounders. The mean (SD) 25(OH)D at V1 was 21.95 (19.64) in the Non-PE group and 17.76 (13.21) in the PE group. A decrease in the concentrations of vitamin D (ng ml^-1) in mid-pregnancy (V2) and at delivery was associated with an increased risk of preeclampsia (0.31 [95% CI 0.11, 0.86], p = 0.024 and 0.24 [95% CI 0.08, 0.77], p = 0.016), respectively. Our finding of lower vitamin D concentrations in mid-pregnancy, before women developed clinical preeclampsia, suggests that vitamin D may have a role in its pathophysiology.

Difference in Levels of Vitamin D between Indoor and Outdoor Athletes: A Systematic Review and Meta-Analysis

Vitamin D, its importance in different processes taking place in the human body, the effects of abnormal levels of this hormone, either too low or too high, and the need for supplementation have been extensively researched thus far. Variances in exposure to sunlight can cause vitamin D levels to fluctuate. Indoor activity can be a factor for these fluctuations and can lead to a decrease in vitamin D levels. We conducted a systematic review and meta-analysis aiming to identify whether indoor compared to outdoor training has a significant influence on vitamin D levels; we also performed subgroup analyses and multivariate meta-regression. The type of training has an impact on vitamin D levels that is influenced by multiple cofounders. In a subgroup analysis not considering cofounders, the mean serum vitamin D was 3.73 ng/mL higher in outdoor athletes, a difference which barely fails to achieve significance (p = 0.052, a total sample size of 5150). The indoor-outdoor difference is only significant (clinically and statistically) when considering studies performed exclusively on Asian athletes (a mean difference of 9.85 ng/mL, p < 0.01, and a total sample size of 303). When performing the analyses within each season, no significant differences are observed between indoor and outdoor athletes. To control for multiple cofounders (the season, latitude, and Asian/Caucasian race) simultaneously, we constructed a multivariate meta-regression model, which estimated a serum vitamin D concentration lower by 4.446 ng/mL in indoor athletes. While a multivariate model suggests that outdoor training is associated with slightly higher vitamin D concentrations when controlling for the season, latitude, and Asian/Caucasian race, the type of training has a numerically and clinically small impact. This suggests that vitamin D levels and the need for supplementation should not be decided based on training type alone.

Clinical and laboratory parameters associated with pregnancy outcomes in patients undergoing frozen euploid blastocyst transfer

RESEARCH QUESTION

Which factors impact on clinical pregnancy rate (CPR) and live birth rates (LBR) in euploid frozen embryo transfer (eFET) cycles?

DESIGN

Retrospective observational study including 1660 eFET cycles with 2439 euploid blastocysts, from November 2016 to December 2020. The impact of clinical and laboratory parameters on CPR, biochemical miscarriage rate (BMR), clinical miscarriage rate (CMR) and LBR was evaluated.

RESULTS

CPR per transfer was 63.4%, LBR per transfer 51.6%. CPR and LBR were significantly higher when double embryo transfer (DET) was performed (71.6% versus 57.7%, P < 0.001; 55.2% versus 49.1%, P = 0.016, respectively). However, pregnancy loss was significantly higher in the DET group (28.8% versus 22.8%, P = 0.02). When patients were classified by body mass index (BMI), no differences were observed for CPR, but CMR was lower (P < 0.001) and LBR higher (p = 0.031) for the normal BMI group. The natural cycle protocol revealed lower CMR (P < 0.001) and lower pregnancy loss (P < 0.001); subsequently, higher LBR (57.6%, 48.8%, 45.0%, P = 0.001) compared with hormonal replacement protocol and stimulated cycle. Day of trophectoderm biopsy affected CPR (P < 0.001) and LBR (P < 0.001), yet no differences were observed for BMR, CMR or pregnancy loss. The multivariate analysis showed that day 6/7 embryos had lower probabilities for pregnancy; overweight and obesity had a negative impact on LBR, and natural cycle improved LBR (adjusted odds ratio 1.445, 95% confidence interval 0.519-0.806).

CONCLUSIONS

Day of biopsy affected CPR, while BMI and endometrial preparation protocol were associated with LBR in eFET. DET should be discouraged as it will increase the risk of pregnancy loss. Women with higher BMI should be aware of the higher risk of pregnancy loss and lower LBR even though a euploid blastocyst is transferred.

Single cell RNA sequencing research in maternal fetal interface

The maternal-fetal interface is an essential environment for embryonic growth and development, and a successful pregnancy depends on the dynamic balance of the microenvironment at the maternal-fetal interface. Single-cell sequencing, which unlike bulk sequencing that provides averaged data, is a robust method for interpreting the cellular and molecular landscape at single-cell resolution. With the support of single-cell sequencing, the issue of maternal-fetal interface heterogeneity during pregnancy has been more deeply elaborated and understood, which is important for a deeper understanding of physiological and pathological pregnancy. In this paper, we analyze the recent studies of single-cell transcriptomics in the maternal-fetal interface, and provide new directions for understanding and treating various pathological pregnancies.