Key takeaways:
- Researchers identified 3 NAD-related metabolites—1MNA, 2PY, and 4PY—that are consistently elevated in women with recurrent pregnancy loss.
- The findings build on earlier work linking low NAD levels to miscarriage, highlighting vitamin B3 metabolism as a key factor in reproductive outcomes.
- Significant metabolite differences were observed across whole blood, plasma, and urine, with NAM-driven elevations affecting multiple biological matrices.
- Plasma 1MNA showed a measurable association with recurrent miscarriage risk, and a model combining 1MNA, 2PY, and 4PY achieved strong predictive accuracy.
- Investigators concluded that these metabolites may serve as biomarkers for recurrent miscarriage, supporting the need for further research into NAD pathways in pregnancy.
There are 3 NAD-related metabolites common in patients with recurrent pregnancy loss, as discovered by researchers from the Victor Chang Cardiac Research Institute, University of Sydney, and the Royal Hospital for Women.1
According to investigators, this data may help identify the risk of pregnancy loss in women, alongside potentially expanding treatment. It also builds upon 2017 research linking low NAD levels to miscarriage, but in the case of recurrent pregnancy loss, it goes beyond low levels to highlight the role of vitamin B3 metabolism in reproductive outcomes.
“Every miscarriage is heartbreaking,” said Hartmut Cuny, PhD, senior postdoctoral student at the Victor Chang Cardiac Research Institute. “Our goal is to understand the biology behind them, so that in time, fewer families have to go through such loss.”
Defining recurrent miscarriage
The study was conducted to compare levels of NAD and other metabolites in women with vs without a history of miscarriage.2 Participants included women aged 20 to 40 years recruited from the Royal Hospital for Women. Those without pregnancy in the 12 months before recruitment and no more than 1 prior miscarriage were included as controls.
Patients with at least 2 spontaneous miscarriages under 20 weeks’ gestation were included in the recurrent miscarriage group. Exclusion criteria included known chromosomal source of miscarriage, termination of pregnancy, and ectopic pregnancy.
Data was obtained through a questionnaire completed by participants online and included sociodemographic characteristics, height, weight, diet, lifestyle, health, medication, and supplement use. Physical activity and medical condition data was also collected. Patients who self-reported as vegans or having diets with certain exclusions were classified as having dietary restrictions.
Morning blood and urine spot samples were obtained from each participant following overnight fasting. Another 24-hour urine sample was provided as soon as possible by nonpregnant patients. Ultra-high performance liquid chromatography–tandem mass spectrometry was used to extract and quantify metabolites.
Significant differences in metabolite levels identified
There were 37 women with recurrent miscarriages and 51 non-pregnant controls included in the final analysis, the former of whom provided samples between 6 and 104 weeks following the last pregnancy and miscarriage. Of these patients, 78% were taking vitamin supplements, and 41% were born in Australia, vs 35% and 73%, respectively, among controls.
Significant between-group differences were identified for the following:
- 9 metabolites in whole blood
- 6 metabolites in plasma
- 5 metabolites in urine
The most significant elevations in the recurrent miscarriage group were reported for 1-methylnicotinamide (1MNA), N-methyl-2-pyridone-5-carboxamide (2PY), and N-methyl-4-pyridone-3-carboxamide (4PY) levels in matrices, anthranilic acid (AA) in whole blood, and nicotinamide (NAM) in urine.
However, the proportion of 1MNA, 2PY, and 4PY to each other did not differ between groups. This indicated that elevated NAM levels led to an increase in NAD-related metabolites, making all 3 biological matrices eligible to identify changes in metabolites.
NAD salvage pathway activity
Significant increases in NAD Salvage Pathway metabolites were also observed among patients with recurrent miscarriage vs controls, highlighting an elevated NAD precursor availability in these patients. However, not all metabolic trends were consistent between matrices, with AA levels only differing in whole blood.
In the univariate analysis, only 1MNA in plasma remained associated with recurrent miscarriage, with a 2% increase in risk for every 1-unit increase in 1MNA. However, the greatest predictive accuracy was reported when including 1MNA, 2PY, and 4PY in the model, with an area under the curve of 0.81.
Overall, these results indicated 1MNA, 2PY, and 4PY as potential biomarkers of recurrent miscarriage risk. Investigators concluded further research is needed to establish these links.
“Given the numerous essential roles of NAD for embryonic development, further research into the role of NAD and related metabolites in miscarriage causation will improve our understanding towards preventative intervention strategies,” wrote investigators.
References
- New clues to why some women experience recurrent miscarriage. Victor Chang Cardiac Research Institute. November 19, 2025. Accessed December 2, 2025. https://www.eurekalert.org/news-releases/1106594.
- Cuny H, Shand AW, Goth J, et al. Identification of potential NAD-related biomarkers of recurrent miscarriage risk. Human Reproduction. 2025. doi:10.1093/humrep/deaf195
