The Role of Early Pregnancy Maternal Selenium Levels on the Risk for Small-for-Gestational Age Newborns

Associations between maternal and infant selenium status and child growth in a birth cohort from Dhaka, Bangladesh

Deficiency of essential trace element, Se, has been implicated in adverse birth outcomes and in child linear growth because of its important role in redox biology and associated antioxidant effects. We used data from a randomised controlled trial conducted among a cohort of pregnant and lactating women in Dhaka, Bangladesh to examine associations between Se biomarkers in whole blood (WBSe), serum and selenoprotein P (SEPP1) in maternal delivery and venous cord (VC) blood. Associations between Se biomarkers, birth weight and infant growth outcomes (age-adjusted length, weight, head circumference and weight-for-length z-scores) at birth, 1 and 2 years of age were examined using regression analyses. WB and serum Se were negatively associated with birth weight (adjusted β, 95 % CI, WBSe delivery: −26·6 (–44·3, −8·9); WBSe VC: −19·6 (–33·0, −6·1)); however, delivery SEPP1 levels (adjusted β: −37·5 (–73·0, −2·0)) and VC blood (adjusted β: 82·3 (30·0, 134·7)) showed inconsistent and opposite associations with birth weight. Positive associations for SEPP1 VC suggest preferential transfer from mother to fetus. We found small associations between infant growth and WBSe VC (length-for-age z-score β, 95 % CI, at birth: −0·05 (–0·1, −0·01)); 12 months (β: −0·05 (–0·08, −0·007)). Weight-for-age z-score also showed weak negative associations with delivery WBSe (at birth: −0·07 (–0·1, −0·02); 12 -months: −0·05 (–0·1, −0·005)) and in WBSe VC (at birth: −0·05 (–0·08, −0·02); 12 months: −0·05 (–0·09, −0·004)). Given the fine balance between essential nutritional and toxic properties of Se, it is possible that WB and serum Se may negatively impact growth outcomes, both in utero and postpartum.

Content of selected heavy metals in the umbilical cord blood and anthropometric data of mothers and newborns in Poland: preliminary data

The ability to accumulate metals in organs and tissues leads to disturbances in the physiological functioning of the body, causing oxidative stress. This negatively affects the functioning of the placenta and may result in miscarriages, premature birth and fetal growth disorders. The aim of the study was to examine the relationship between the levels of selected heavy metals in umbilical cord blood and anthropometric parameters of mothers and the newborns. Content of elements in umbilical cord blood has been assessed by high-resolution inductively coupled plasma optical emission spectroscopy (ICP-OES). The study results were collected and statistically analyzed using IBM SPSS Statistics software (PS IMAGO). The Pearson correlation coefficient was used to test for associations between selected variables. Regression analysis was conducted to identify predictors of anthropometric parameters of studied women and newborns. The study group consisted of women aged 19-41, whose pregnancy was uncomplicated and were not exposed to heavy metals due to their work or smoking. The following metals were identified in all collected cord blood samples: lead (26.25 ± 9.32 µg/L), zinc (2025.24 ± 717.83 µg/L), copper (749.85 ± 203.86 µg/L), manganese (32.55 ± 13.58 µg/L), chromium (8.34 ± 2.16 µg/L) and selenium (158.46 ± 41.58 µg/L). The conducted statistical analysis indicated the relationship between the copper content in the umbilical cord blood and the weight gain of pregnant women. A significant relationship was observed between newborn head circumference and chromium content. In addition, significant positive correlations were found between the content of zinc and copper, manganese and lead, manganese and selenium, lead and selenium, and lead and chromium in umbilical cord blood. The ratio of zinc to copper concentrations was related to neonatal head circumference. Weight gain in pregnant women is positively correlated with the copper level in umbilical cord blood. There is an association between head circumference at birth and the chromium concentration in umbilical cord blood. Copper and zinc levels in umbilical cord blood are positively correlated with head circumference at birth.

Placental levels of essential and non-essential trace element in relation to neonatal weight in Northwestern Spain: application of generalized additive models

Adequate gestational progression depends to a great extent on placental development, which can modify maternal and neonatal outcomes. Any environmental toxicant, including metals, with the capacity to affect the placenta can alter the development of the pregnancy and its outcome. The objective of this study was to correlate the placenta levels of 14 essential and non-essential elements with neonatal weight. We examined relationships between placental concentrations of arsenic, cadmium, cobalt, copper, mercury, lithium, manganese, molybdenum, nickel, lead, rubidium, selenium, strontium, and zinc from 79 low obstetric risk pregnant women in Ourense (Northwestern Spain, 42°20'12.1″N 7°51.844'O) with neonatal weight. We tested associations between placental metal concentrations and neonatal weight by conducting multivariable linear regressions using generalized linear models (GLM) and generalized additive models (GAM). While placental Co (p = 0.03) and Sr (p = 0.048) concentrations were associated with higher neonatal weight, concentrations of Li (p = 0.027), Mo (p = 0.049), and Se (p = 0.02) in the placenta were associated with lower newborn weight. Our findings suggest that the concentration of some metals in the placenta may affect fetal growth.

The Effects of BSA-Stabilized Selenium Nanoparticles and Sodium Selenite Supplementation on the Structure, Oxidative Stress Parameters and Selenium Redox Biology in Rat Placenta

The chemical element selenium (Se) is a nonmetal that is in trace amounts indispensable for normal cellular functioning. During pregnancy, a low Se status can increase the risk of oxidative stress. However, elevated concentrations of Se in the body can also cause oxidative stress. This study aimed to compare the effects of BSA-stabilized Se nanoparticles (SeNPs, Se0) (BSA-bovine serum albumin) and inorganic sodium selenite (NaSe, Se+4) supplementation on the histological structure of the placenta, oxidative stress parameters and the total placental Se concentration of Wistar rats during pregnancy. Pregnant females were randomized into four groups: (i) intact controls; (ii) controls that were dosed by daily oral gavage with 8.6% bovine serum albumin (BSA) and 0.125 M vit C; (iii) the SeNP group that was administered 0.5 mg of SeNPs stabilized with 8.6% BSA and 0.125 M vit C/kg bw/day by oral gavage dosing; (iv) the NaSe group, gavage dosed with 0.5 mg Na2SeO3/kg bw/day. The treatment of pregnant females started on gestational day one, lasted until day 20, and on day 21 of gestation, the fetuses with the placenta were removed from the uterus. Our findings show that the mode of action of equivalent concentrations of Se in SeNPs and NaSe depended on its redox state and chemical structure. Administration of SeNPs (Se0) increased fetal lethality and induced changes in the antioxidative defense parameters in the placenta. The accumulation of Se in the placenta was highest in SeNP-treated animals. All obtained data indicate an increased bioavailability of Se in its organic nano form and Se0 redox state in comparison to its inorganic sodium selenite form and Se+4 redox state.

Transcriptomic analysis reveals the effects of maternal selenium deficiency on placental transport, hormone synthesis, and immune response in mice

Selenium deficiency has been considered to increase the risk of gestational complications. Our previous work showed that maternal selenium deficiency suppressed proliferation, induced autophagy dysfunction and apoptosis in the placenta of mice. However, other effects of maternal selenium deficiency on the placenta and the underlying mechanisms remain unclear. In the present study, dietary selenium deficiency in dams significantly suppressed glutathione peroxidase (GSH-Px) activity, total antioxidant capacity (T-AOC), and increased malondialdehyde (MDA) content in the placentae, confirming the oxidative stress in the placenta. By transcriptome sequencing analysis, the DEGs were involved in many biological processes, including ion transport, lipid metabolic process, immune response, transmembrane transport, and others. According to the KEGG analysis, the DEGs were primarily enriched in metabolic pathways, PI3K-Akt signaling pathway, and others. Among these, the steroid hormone biosynthesis pathway enriched the most DEGs. Hsd3b1, an ER enzyme involved in progesterone synthesis, was validated downregulated. Consistently, the progesterone content in the serum of the selenium-deficient group was decreased. Ion transporters and transmembrane transporters, such as Heph, Trf, Slc39a8, Slc23a1, Atp7b, and Kcnc1, were reduced in the selenium-deficient placentae. Immune response-related genes, including Ccl3, Ccl8, Cxcl10, and Cxcl14, were increased in the selenium-deficient placentae, along with an increase in macrophage number. These results suggested that maternal selenium deficiency may impair progesterone biosynthesis, reduce nutrient transporters expression, and promote immune response by increasing the oxidative stress of the placentae. This present study provides a novel insight into the possible cause of placenta disorder during pregnancy.

Individual and mixed metal maternal blood concentrations in relation to birth size: An analysis of the Japan Environment and Children's Study (JECS)

BACKGROUND

Growth restriction in the prenatal period is a significant public health concern. Metals can negatively affect birth size, and pregnant women may be exposed to metal mixtures. Comprehensive studies analyzing the effects of combined metal exposure with accurate individual blood metal concentrations are limited. The current study investigated the associations between maternal metal exposure and birth size in a large, nationwide Japanese cohort using individual and mixed model approaches.

METHODS

Lead, cadmium, mercury, selenium, and manganese blood concentrations were measured in pregnant women in the Japan Environment and Children's Study (JECS). Measurements of infant birth size-including body weight, body length, and head and chest circumference-were collected. Linear and logistic regressions were used for birth size measurements and the odds of an infant being small in size for gestational age, respectively. Associations between combined metal mixtures and measurements at birth were evaluated using quantile g-computation and Bayesian kernel machine regression (BKMR).

RESULTS

Of the 103,060 JECS pregnancies, 93,739 mother-infant pairs were analyzed. The linear regression models showed that lead, selenium, cadmium, and manganese-but not mercury-were associated with body weight. Cadmium was associated with length and chest circumference and mercury was associated with head circumference. Quantile g-computation revealed that manganese increased infant birth weight, length, head circumference, and chest circumference. Lead was the strongest negative factor for infant birth weight, length, head circumference, and chest circumference. The BKMR analysis revealed that the metals had an additive, rather than a synergistic effect.

CONCLUSION

Metal exposure is associated with infant birth size, with lead and manganese playing a more significant role in Japan. The effects of prenatal combined metal exposure at low levels warrant public health attention.

Melatonin Alleviates Oxidative Stress Induced by H2O2 in Porcine Trophectodern Cells

Placental oxidative stress has been implicated as a main risk factor for placental dysfunction. Alleviation of oxidative stress and enhancement of antioxidant capacity of porcine trophectoderm (PTr2) cells are effective means to maintaining normal placental function. The present study was conducted to evaluate the protective effect of melatonin (MT) on H₂O₂-induced oxidative damage in PTr2 cells. Our data revealed that pretreatment with MT could significantly improve the decrease in cell viability induced by H₂O₂, and reduce intracellular reactive oxygen species (ROS) levels and the ratio of apoptotic cells. Here, we compared the transcriptomes of untreated versus melatonin-treated PTr2 cells by RNA-seq analysis and found that differentially expressed genes (DEGs) were highly enriched in the Wnt signaling, TGF-beta signaling and mTOR signaling pathways. Moreover, pretreatment with MT upregulated the antioxidant-related genes such as early growth response3 (EGR3), WAP four-disulfide core domain1 (WFDC1), heme oxygenase1 (HMOX1) and vimentin (VIM). These findings reveal that melatonin protects PTr2 cells from H₂O₂-induced oxidative stress damage.

Selenoproteins in the Human Placenta: How Essential Is Selenium to a Healthy Start to Life?

Selenium is an essential trace element required for human health, and selenium deficiency has been associated with many diseases. The daily recommended intake of selenium is 60 µg/day for adults, which increases to 65 µg/day for women when pregnant. Selenium is incorporated into the 21st amino acid, selenocysteine (sec), a critical component of selenoproteins that plays an important role in a variety of biological responses such as antioxidant defence, reactive oxygen species (ROS) signalling, formation of thyroid hormones, DNA synthesis and the unfolded protein response in the endoplasmic reticulum (ER). Although 25 selenoproteins have been identified, the role of many of these is yet to be fully characterised. This review summarises the current evidence demonstrating that selenium is essential for a healthy pregnancy and that poor selenium status leads to gestational disorders. In particular, we focus on the importance of the placental selenoproteome, and the role these proteins may play in a healthy start to life.

Association of selenium, zinc and copper concentrations during pregnancy with birth weight: A systematic review and meta-analysis

BACKGROUND

Normal fetal growth is associated with maternal nutrition. Trace elements play important roles in fetus growth. This review aims to provide a summary of the literature evaluating the relation between selenium, zinc and copper levels during pregnancy with birth weight.

METHOD

A systematic literature search was conducted in Medline database (PubMed), Scopus, Web of science and Google scholar up to September 2020. Fifty observational studies were included in the final analyses. The desired pooled effect size was considered as standardized mean differences with 95 % CI or correlation. Cochran's Q statistic was used to test the heterogeneity between the included studies (I²).

RESULT

A significant differences were found between pooled standardized mean differences (SMD) of umbilical cord blood copper levels in small-for-gestational age birth weight (SGA) and appropriate-for-gestational age birth weight (AGA) (SMD: 0.34 μg/L, 95 % CI: 0.13 to 0.56). There was a significant pooled correlation between umbilical cord blood selenium concentrations and birth weight (r: 0.08, 95 % CI: 0.01 to 0.16). A significant pooled correlation was found between umbilical cord blood zinc concentrations and birth weight (r: 0.09, 95 % CI: 0.04 to 0.15), with significant heterogeneity (I² % = 0.63). There was significant positive association between maternal blood zinc concentrations and birth weight.

CONCLUSION

Findings showed the association of trace elements including selenium, zinc and copper during pregnancy with birth weight. There was significant correlation between umbilical cord and maternal blood selenium and zinc levels with birth weight. The umbilical cord blood copper levels in SGA birth weight was higher than copper levels in AGA birth weight.

Moderate Freshwater Fish Intake, but Not n-3 Polyunsaturated Fatty Acids, Is Associated with a Reduced Risk of Small for Gestational Age in a Prospective Cohort of Chinese Pregnant Women

BACKGROUND

Although previous studies have found that maternal fish intake is associated with fetal growth, the role of freshwater fish intake remains unknown.

OBJECTIVE

Our aim was to examine the relationships of freshwater fish and n-3 polyunsaturated fatty acids (PUFAs) intake with the risk of small for gestational age (SGA) in Chinese pregnant women.

DESIGN

This was a prospective analysis of data from the Tongji Birth cohort in Wuhan, China, from 2018 to 2021.

PARTICIPANTS/SETTINGS

This study included 1,701 pregnant women who had completed a food frequency questionnaire dietary assessment during mid-pregnancy.

MAIN OUTCOME MEASURES

Intake of fish was assessed by a semi-quantitative food frequency questionnaire. Total intake of n-3 PUFAs was the sum of data collected from both dietary and supplemental sources of n-3 PUFAs. Birth information was extracted from medical records.

STATISTICAL ANALYSES

Multivariate logistic regression models were applied to estimate odds ratios and 95% CIs.

RESULTS

The median (interquartile range) intake of freshwater fish and total n-3 PUFAs was 12.1 (4.3 to 26.4) g/d and 68.2 (24.5 to 370.0) mg/d, respectively. Moderate intake of freshwater fish was associated with reduced risk of SGA. Compared with the lowest quintile (0-3.2 g/d), the multivariable-adjusted odds ratio for women in the fourth quintile of freshwater fish intake (17.9 to 30.0 g/d) was 0.50 (95% CI 0.25 to 0.96). We found a nonlinear association between freshwater fish intake and SGA risk (P_nonlinearity = .027). However, maternal n-3 PUFAs intake was not significantly associated with SGA risk, either from total intake or from dietary sources alone.

CONCLUSIONS

Moderate freshwater fish intake during pregnancy is associated with lower risk of SGA in a Chinese population. This finding provides supportive evidence for freshwater fish intake during pregnancy, particularly for the inland areas of developing countries.

The Role of Maternal Weight in the Hierarchy of Macrosomia Predictors; Overall Effect of Analysis of Three Prediction Indicators

So far it has not been established which maternal features play the most important role in newborn macrosomia. The aim of this study is to provide assessment of a hierarchy of twenty six (26) maternal characteristics in macrosomia prediction. A Polish prospective cohort of women with singleton pregnancy (N = 912) which was recruited in the years 2015–2016 has been studied. Two analyses were performed: for probability of macrosomia > 4000 g (n = 97) (vs. 755 newborns 2500–4000 g); and for birthweight > 90th percentile (n = 99) (vs. 741 newborns 10–90th percentile). A multiple logistic regression was used (with 95% confidence intervals (CI)). A hierarchy of significance of potential predictors was established after summing up of three prediction indicators (NRI, IDI and AUC) calculated for the basic prediction model (maternal age + parity) extended with one (test) predictor. ‘Net reclassification improvement’ (NRI) focuses on the reclassification table describing the number of women in whom an upward or downward shift in the disease probability value occurred after a new factor had been added, including the results for healthy and ill women. ‘Integrated discrimination improvement’ (IDI) shows the difference between the value of mean change in predicted probability between the group of ill and healthy women when a new factor is added to the model. The area under curve (AUC) is a commonly used indicator. Results. The macrosomia risk was the highest for prior macrosomia (AOR = 7.53, 95%CI: 3.15–18.00, p < 0.001). A few maternal characteristics were associated with more than three times higher macrosomia odds ratios, e.g., maternal obesity and gestational age ≥ 38 weeks. A different hierarchy was shown by the prediction study. Compared to the basic prediction model (AUC = 0.564 (0.501–0.627), p = 0.04), AUC increased most when pre-pregnancy weight (kg) was added to the base model (AUC = 0.706 (0.649–0.764), p < 0.001). The values of IDI and NRI were also the highest for the model with maternal weight (IDI = 0.061 (0.039–0.083), p < 0.001), and (NRI = 0.538 (0.33–0.746), p < 0.001). Adding another factor to the base model was connected with significantly weaker prediction, e.g., for gestational age ≥ 38 weeks (AUC = 0.602 (0.543–0.662), p = 0.001), (IDI = 0.009 (0.004; 0.013), p < 0.001), and (NRI = 0.155 (0.073; 0.237), p < 0.001). After summing up the effects of NRI, IDI and AUC, the probability of macrosomia was most strongly improved (in order) by: pre-pregnancy weight, body mass index (BMI), excessive gestational weight gain (GWG) and BMI ≥ 25 kg/m². Maternal height, prior macrosomia, fetal sex-son, and gestational diabetes mellitus (GDM) occupied an intermediate place in the hierarchy. The main conclusions: newer prediction indicators showed that (among 26 features) excessive pre-pregnancy weight/BMI and excessive GWG played a much more important role in macrosomia prediction than other maternal characteristics. These indicators more strongly highlighted the differences between predictors than the results of commonly used odds ratios.

Maternal selenium deficiency during gestation is positively associated with the risks for LBW and SGA newborns in a Chinese population

BACKGROUND

Maternal selenium (Se) deficiency is associated with some adverse pregnant outcomes. However, it remains controversial whether maternal Se deficiency during gestation enhances the risks for low-birth-weight (LBW) and small-for-gestational-age (SGA) newborns.

METHODS

For our cohort study, total 3133 mother-and-infant pairs were selected. Maternal serum Se concentration was detected by graphite furnace atomic absorption spectrometry. According to international references for maternal serum Se concentration, subjects were divided into Se deficiency (<45.0 μg/L), Se insufficiency (45.0-94.9 μg/L) and Se sufficiency (≥95.0 μg/L).

RESULTS

There was a positive relation of maternal serum Se concentration in gestation and neonatal birth weight. Further analysis showed that the risks for LBW and SGA in SD group were significantly higher than that in SI and SS group, the adjusted ORs for LBW and SGA newborns were 1.87 (95%CI: 1.02, 3.45; P = 0.04) and 1.47 (95%CI: 1.07, 2.02; P = 0.02) in SI group, and 3.92 (95%CI: 2.03, 7.57; P < 0.001) and 2.77 (95%CI: 1.92, 4.02; P < 0.001) in SD group compared to SS group. In different gender subgroup, positive relations were observed between maternal Se deficiency and the risk for LBW girls, as well as the risks for both SGA girls and boys.

CONCLUSION

Maternal Se deficiency in gestation was positively associated with the risk for LBW girls, as well as the risks for both SGA girls and boys.

Low selenium intake is associated with postpartum weight retention in Chinese women and impaired physical development of their offspring

The aim of this study was to investigate the association between daily Se intake and postpartum weight retention (PPWR) among Chinese lactating women, and the impact of their Se nutritional status on infants' physical development. Se contents in breast milk and plasma collected from 264 lactating Chinese women at the 42nd day postpartum were analysed with inductively coupled plasma MS. Daily Se intake was calculated based on plasma Se concentration. The dietary data of 24-h records on three consecutive days were collected. Infant growth status was evaluated with WHO standards by Z-scores. Linear regression analyses and multinomial logistic regression were conducted to examine the impact of Se disequilibrium (including other factors) on PPWR and growth of infants, respectively. The results indicated that: (1) the daily Se intake of the subjects was negatively associated with their PPWR (B = -0·002, 95 % CI - 0·003, 0·000, P = 0·039); (2) both insufficient Se daily intake (B = -0·001, OR 0·999, 95 % CI 0·998, 1·000, P = 0·014) and low level of Se in milk (B = -0·025, OR 0·975, 95 % CI 0·951, 0·999, P = 0·021) had potential associations with their infants' wasting, and low level of Se in milk (B = -0·159, OR 0·853, 95 % CI 0·743, 0·980, P = 0·024) had a significant association with their infants' overweight. In conclusion, the insufficient Se nutritional status of lactating Chinese women was first found as one possible influencing factor of their PPWR as well as low physical development of their offspring.

Smoking and Smoking Cessation in the Risk for Fetal Growth Restriction and Low Birth Weight and Additive Effect of Maternal Obesity

Many studies have shown that neonates of smoking mothers have a lower birth weight, but several issues remain poorly studied, e.g., the effects of giving up smoking or the combined effects of smoking and maternal obesity. Therefore, we evaluated a prospective cohort of 912 mothers in a single pregnancy, recruited in Poland, in 2015−2016. In the cohort, we recorded 72 (7.9%) newborns with birth weight <10th percentile, 21 (2.3%) fetal growth restriction (FGR) cases, and 60 (6.6%) low birth weight (LBW, <2500 g) newborns. In the cohort, 168 (18.4%) women smoked before pregnancy; the mean number of cigarettes/day was 10.8 (1–30), and the mean number of years of cigarette smoking was 8.5 (1–25). Among smokers, 57 (6.3%) women smoked in the first trimester. Adjusted odds ratio (AOR) of newborn outcomes (with 95% confidence intervals, CI) was calculated in multi-dimensional logistic regressions. Compared to participants who had never smoked, smoking before pregnancy was associated with a higher odds ratio of birth weight <10th percentile (AOR = 1.93, CI: 1.08–3.44, p = 0.027), but the result for LBW (AOR = 2.76, CI: 1.05–7.26, p = 0.039) and FGR (AOR = 1.13, CI: 0.38–3.36, p = 0.822) had the wider confidence interval or was insignificant. Effects of smoking cessation before pregnancy were statistically insignificant for the studied outcomes. Smoking in the first trimester was associated with a higher risk of birth weight <10th percentile (AOR = 4.68, CI: 2.28–9.62, p < 0.001), LBW (AOR = 6.42, CI: 1.84–22.36, p = 0.004), and FGR (AOR = 3.60, CI: 0.96–13.49, p = 0.057). Smoking cessation in the second/third trimester was associated with a higher odds ratio of birth weight <10th percentile (AOR = 4.54, CI: 1.58–13.02, p = 0.005), FGR (AOR = 3.36, CI: 0.6–18.74, p = 0.167), and LBW (AOR = 2.14, CI: 0.62–7.36), p = 0.229), to a similar degree to smoking in the first trimester. The odds ratios were higher in the subgroup of pre-pregnancy body mass index ≥25 kg/m² for the risk of birth weight <10th percentile (AOR = 6.39, CI: 2.01–20.34, p = 0.002) and FGR (AOR = 6.25, CI: 0.86–45.59, p = 0.071). The length of cigarette smoking time was also the risk factor for studied outcomes. Conclusions: Smoking in the first trimester increased the studied risks, and the coexistence of excessive maternal weight increased the effects. Smoking cessation during the second/third trimester did not have a protective effect.

Low Selenium Levels in Amniotic Fluid Correlate with Small-For-Gestational Age Newborns

Background: Identifying women at risk for small-for-gestational-age newborns (SGA) is an important challenge in obstetrics. Several different risk factors have been suggested to contribute to the development of SGA. Previous research is inconclusive on the role selenium (Se) plays in the development of SGA. The aim of the study was therefore to explore the role of Se concentrations in amniotic fluid in order to understand its possible role in the development of SGA. Study Design: This prospective, single center study investigated the relationships between Se concentrations in amniotic fluid and pregnancy outcomes. Amniotic fluid was collected from pregnant women during amniocentesis at 16/17 weeks of pregnancy. Se values were determined using the electrothermal atomic absorption spectrometry and expressed in µg/L. Characteristics of mothers and newborns were obtained from women and delivery records. Results: 327 samples of amniotic fluid were evaluated. Patients with SGA newborns had significantly lower mean values of amniotic fluid concentrations of Se compared to appropriate-for-gestational-age (AGA) newborns (4.8 ± 1.9 µg/L versus 5.6 ± 2.5 µg/L (p = 0.017)). Adjusting for different risk factors, Se remained the only significant factor impacting the outcome of a newborn (b = −0.152, s.e. = 0.077; p < 0.048). Se levels in amniotic fluid did not correlate with pre-eclampsia or preterm delivery. Conclusion: Amniotic fluid Se levels represent a viable root of further investigation and assessment in order to identify women with low birth weight newborns early. Women with decreased Se levels had a statistically significant chance of developing SGA. Further research is needed to elucidate the link between Se, other trace elements, and other risk factors and their impact on the development of SGA newborns.

Selenium and at-risk pregnancy: challenges and controversies

Selenium (Se), an essential trace element, is inserted as selenocysteine into an array of functional proteins and forms the core of various enzymes that play a cardinal role in antioxidant defense mechanisms, in redox regulation, and in thyroid hormone metabolism. Variations in plasma Se are due to nutritional habits, geographic and ethnic differences, and probably to genetic polymorphisms, the latter still to be conclusively established. Se concentrations were reported to be low in women of reproductive age in the UK, decreasing further during pregnancy, this resulting in low plasma and placental antioxidant enzyme activities. Since low serum Se levels have been found in women with preeclampsia, it has been hypothesized that low maternal Se status during early gestation may be an indicator of preterm birth. Moreover, it is documented that Se administration during pregnancy tendentially reduced the markers of thyroid autoimmunity and the incidence of maternal hypothyroidism in the postpartum period. Importantly, low Se levels in pregnant women affect fetal growth and augment the risk of delivering a small-for-gestational age infant by reducing placental antioxidant defense, while low Se in the third trimester is thought to indicate increased demands by the placenta, an issue which requires further confirmation. There is evidently a need for double-blind, placebo-controlled studies to better determine the efficacy and safety of Se supplementation in pregnancy at high risk for complications, and for measurement of Se levels or of selenoprotein P, the most reliable parameter of Se status, particularly in selenopenic regions.

The Influence of Maternal BMI on Adverse Pregnancy Outcomes in Older Women

As mothers age, the risk of adverse pregnancy outcomes may increase, but the results so far are controversial and several issues remain unknown, such as the impact of maternal weight on the effects associated with older age. In a prospective cohort of 912 Polish women with singleton pregnancies (recruited in 2015–2016), we assessed the pregnancy outcomes depending on the mother’s age (18–24, 25–29, 30–34, 35–39, and ≥40 years). Women aged ≥35 years (vs. <35 years) were assessed in terms of body mass index (BMI). Multidimensional logistic regression was used to calculate the odds ratios (with 95% confidence intervals) of the pregnancy results. The risk profiles (using the Lowess method) were applied to determine the threshold risk. We found that both the youngest and the oldest group members displayed higher adjusted odds ratios of preeclampsia (PE), intrauterine growth restriction (IUGR), and preterm birth <37th week (U-shaped risk). In the remaining cases, the age ≥40 years, compared to the youngest age 18–24 years, was associated with a higher adjusted risk of gestational hypertension (GH) (AOR = 5.76, p = 0.034), gestational diabetes mellitus GDM-1 (AOR = 7.06, p = 0.016), cesarean section (AOR = 6.97, p <0.001), and low birth weight LBW (AOR = 15.73, p = 0.033) as well as macrosomia >4000 g (AOR = 8.95, p = 0.048). We found that older age ≥35 years (vs. <35 years) was associated with higher adjusted odds ratios of all the pregnancy outcomes investigated. In obese women, these adverse older age related results were found to be more intense in GH study, as well as (though weaker) in birth <37th week study, small-for-gestational age birth weight (SGA), LBW, large-for-gestational age birth weight (LGA), and macrosomia. In overweight women, these adverse older age related results were found to be more intense in preterm birth study, as well as (though weaker) in SGA and LBW. In underweight women, adverse pregnancy outcomes related to older age were more intense in a study of cesarean section. At the same time, underweight was associated with reversal of some negative effects of older age (we found lower odds ratios of GDM-1 diabetes). The maternal threshold age above which the risk of GH, PE, GDM, caesarean section, and preterm birth increased was 33–34 years (lower than the threshold of 35 years assumed in the literature), and the threshold risk of IUGR, LBW, SGA, LGA, and macrosomia was 36–37 years. Main conclusions: Older maternal age was associated with a higher chance of all kinds of obstetric complications. Older women should particularly avoid obesity and overweight.

Nutrients, Mitochondrial Function, and Perinatal Health

Mitochondria are active independent organelles that not only meet the cellular energy requirement but also regulate central cellular activities. Mitochondria can play a critical role in physiological adaptations during pregnancy. Differences in mitochondrial function have been found between healthy and complicated pregnancies. Pregnancy signifies increased nutritional requirements to support fetal growth and the metabolism of maternal and fetal tissues. Nutrient availability regulates mitochondrial metabolism, where excessive macronutrient supply could lead to oxidative stress and contribute to mitochondrial dysfunction, while micronutrients are essential elements for optimal mitochondrial processes, as cofactors in energy metabolism and/or as antioxidants. Inadequate macronutrient and micronutrient consumption can result in adverse pregnancy outcomes, possibly through mitochondrial dysfunction, by impairing energy supply, one-carbon metabolism, biosynthetic pathways, and the availability of metabolic co-factors which modulate the epigenetic processes capable of establishing significant short- and long-term effects on infant health. Here, we review the importance of macronutrients and micronutrients on mitochondrial function and its influence on maternal and infant health.

First Trimester Microelements and their Relationships with Pregnancy Outcomes and Complications

Microelements involved in the oxidative balance have a significant impact on human health, but their role in pregnancy are poorly studied. We examined the relationships between first trimester levels of selenium (Se), iron (Fe), zinc (Zn), and copper (Cu), as well as maternal characteristics and pregnancy results. The data came from a Polish prospective cohort of women in a single pregnancy without chronic diseases. A group of 563 women who had a complete set of data, including serum microelements in the 10–14th week was examined, and the following were found: 47 deliveries <37th week; 48 cases of birth weight <10th and 64 newborns >90th percentile; 13 intrauterine growth restriction (IUGR) cases; 105 gestational hypertension (GH) and 15 preeclampsia (PE) cases; and 110 gestational diabetes mellitus (GDM) cases. The microelements were quantified using mass spectrometry. The average concentrations (and ranges) of the elements were as follows: Se: 60.75 µg/L (40.91–125.54); Zn: 618.50 µg/L (394.04–3238.90); Cu: 1735.91 µg/L (883.61–3956.76); and Fe: 1018.33 µg/L (217.55–2806.24). In the multivariate logistic regression, we found that an increase in Se of 1 µg/L reduces the risk of GH by 6% (AOR = 0.94; p = 0.004), the risk of IUGR by 11% (AOR = 0.89; p = 0.013), and the risk of birth <34th week by 7% (but close to the significance) (AOR = 0.93; p = 0.061). An increase in Fe of 100 µg/L reduces the risk of PE by 27% (AOR = 0.73; p = 0.009). In the multivariable linear regression, we found negative strong associations between prepregnancy BMI, Se (β = −0.130; p = 0.002), and Fe (β = −0.164; p < 0.0001), but positive associations with Cu (β = 0.320; p < 0.000001). The relationships between Se and maternal age (β = 0.167; p < 0.0001), Se and smoking (β = −0.106; p = 0.011) and Cu, and gestational age from the 10–14th week (β = 0.142; p < 0.001) were also found. Secondary education was associated with Zn (β = 0.132; p = 0.004) and higher education was associated with Cu (β = −0.102; p = 0.023). A higher financial status was associated with Fe (β = 0.195; p = 0.005). Other relationships were statistically insignificant. Further research is needed to clarify relationships between first trimester microelements and pregnancy complications. In addition, attention should be paid to lifestyle-related and socioeconomic factors that affect microelement levels.

Serum Microelements in Early Pregnancy and their Risk of Large-for-Gestational Age Birth Weight

Excessive birth weight has serious perinatal consequences, and it “programs” long-term health. Mother’s nutritional status can be an important element in fetal “programming”; microelements such as selenium (Se), zinc (Zn), copper (Cu), and iron (Fe) are involved in many metabolic processes. However, there are no studies assessing the relationship of the microelements in the peri-conceptual period with the risk of excessive birth weight. We performed a nested case control study of serum microelements’ levels in the 10–14th week of pregnancy and assessed the risk of large-for-gestational age (LGA) newborns using the data from a prospective cohort of pregnant women recruited in 2015–2016 in Poznań, Poland. Mothers delivering LGA newborns (n = 66) were examined with matched mothers delivering appropriate-for-gestational age (AGA) newborns (n = 264). Microelements’ levels were quantified using mass spectrometry. The odds ratios of LGA (and 95% confidence intervals) were calculated by multivariate logistic regression. In the whole group, women with the lowest quartile of Se had a 3 times higher LGA risk compared with women in the highest Se quartile (AOR = 3.00; p = 0.013). Importantly, the result was sustained in the subgroup of women with the normal pre-pregnancy BMI (AOR = 4.79; p = 0.033) and in women with a male fetus (AOR = 6.28; p = 0.004), but it was not sustained in women with a female fetus. There were no statistical associations between Zn, Cu, and Fe levels and LGA. Our study provides some preliminary evidence for the relationships between lower serum Se levels in early pregnancy and a higher risk of large-for-gestational age birth weight. Appropriate Se intake in the periconceptual period may be important for optimal fetal growth.

Maternal Selenium Deficiency in Mice Alters Offspring Glucose Metabolism and Thyroid Status in a Sexually Dimorphic Manner

Selenium is an essential micronutrient commonly deficient in human populations. Selenium deficiency increases the risks of pregnancy complications; however, the long-term impact of selenium deficiency on offspring disease remains unclear. This study investigates the effects of selenium deficiency during pregnancy on offspring metabolic function. Female C57BL/6 mice were allocated to control (>190 μg selenium/kg, n = 8) or low selenium (<50 μg selenium/kg, n = 8) diets prior to mating and throughout gestation. At postnatal day (PN) 170, mice underwent an intraperitoneal glucose tolerance test and were culled at PN180 for biochemical analysis. Mice exposed to selenium deficiency in utero had reduced fasting blood glucose but increased postprandial blood glucose concentrations. Male offspring from selenium-deficient litters had increased plasma insulin levels in conjunction with reduced plasma thyroxine (tetraiodothyronine or T4) concentrations. Conversely, females exposed to selenium deficiency in utero exhibited increased plasma thyroxine levels with no change in plasma insulin. This study demonstrates the importance of adequate selenium intake around pregnancy for offspring metabolic health. Given the increasing prevalence of metabolic disease, this study highlights the need for appropriate micronutrient intake during pregnancy to ensure a healthy start to life.

Dietary Selenium Supplementation Ameliorates Female Reproductive Efficiency in Aging Mice

Female reproductive (ovarian) aging is distinctively characterized by a markedly reduced reproductive function due to a remarkable decline in quality and quantity of follicles and oocytes. Selenium (Se) has been implicated in playing many important biological roles in male fertility and reproduction; however, its potential roles in female reproduction, particularly in aging subjects, remain poorly elucidated. Therefore, in the current study we used a murine model of female reproductive aging and elucidated how different Se-levels might affect the reproductive efficiency in aging females. Our results showed that at the end of an 8-week dietary trial, whole-blood Se concentration and blood total antioxidant capacity (TAOC) were significantly reduced in Se-deficient (0.08 mg Se/kg; Se-D) mice, whereas both of these biomarkers were significantly higher in inorganic (0.33 mg/kg; ISe-S) and organic (0.33 mg/kg; OSe-S) Se-supplemented groups. Similarly, compared to the Se-D group, Se supplementation significantly ameliorated the maintenance of follicles and reduced the rate of apoptosis in ovaries. Meanwhile, the rate of in vitro-produced embryos resulting from germinal vesicle (GV) oocytes was also significantly improved in Se-supplemented (ISe-S and OSe-S) groups compared to the Se-D mice, in which none of the embryos developed to the hatched blastocyst stage. RT-qPCR results revealed that mRNA expression of Gpx1, Gpx3, Gpx4, Selenof, p21, and Bcl-2 genes in ovaries of aging mice was differentially modulated by dietary Se levels. A considerably higher mRNA expression of Gpx1, Gpx3, Gpx4, and Selenof was observed in Se-supplemented groups compared to the Se-D group. Similarly, mRNA expression of Bcl-2 and p21 was significantly lower in Se-supplemented groups. Immunohistochemical assay also revealed a significantly higher expression of GPX4 in Se-supplemented mice. Our results reasonably indicate that Se deficiency (or marginal levels) can negatively impact the fertility and reproduction in females, particularly those of an advancing age, and that the Se supplementation (inorganic and organic) can substantiate ovarian function and overall reproductive efficiency in aging females.