Maternal omega-3 fatty acid intake increases placental labyrinthine antioxidant capacity but does not protect against fetal growth restriction induced by placental ischaemia-reperfusion injury

Exploring the Role of Mediterranean and Westernized Diets and Their Main Nutrients in the Modulation of Oxidative Stress in the Placenta: A Narrative Review

Oxidative stress is a major cellular event that occurs in the placenta, fulfilling critical physiological roles in non-pathological pregnancies. However, exacerbated oxidative stress is a pivotal feature of different obstetric complications, like pre-eclampsia, fetal growth restriction, and other diseases. Compelling evidence supports the relevant role of diet during pregnancy, with pleiotropic consequences for maternal well-being. The present review aims to examine the complex background between oxidative stress and placental development and function in physiological conditions, also intending to understand the relationship between different dietary patterns and the human placenta, particularly how this could influence oxidative stress processes. The effects of Westernized diets (WDs) and high-fat diets (HFDs) rich in ultra-processed foods and different additives are compared with healthy patterns such as a Mediterranean diet (MedDiet) abundant in omega 3 polyunsaturated fatty acids, monounsaturated fatty acids, polyphenols, dietary fiber, and vitamins. Although multiple studies have focused on the role of specific nutrients, mostly in animal models and in vitro, further observational and intervention studies focusing on the placental structure and function in women with different dietary patterns should be conducted to understand the precise influence of diet on this organ.

Prenatal interventions for fetal growth restriction in animal models: A systematic review

Fetal growth restriction (FGR) in human pregnancy is associated with perinatal mortality, short- and long-term morbidities. No prenatal therapy is currently established despite decades of research. We aimed to review interventions in animal models for prenatal FGR treatment, and to seek the next steps for an effective clinical therapy. We registered our protocol and searched MEDLINE, Embase, and The Cochrane Library with no language restrictions, in accordance with the PRISMA guideline. We included all studies that reported the effects of any prenatal intervention in animal models of induced FGR. From 3257 screened studies, 202 describing 237 interventions were included for the final synthesis. Mice and rats were the most used animals (79%) followed by sheep (16%). Antioxidants (23%), followed by vasodilators (18%), nutrients (14%), and immunomodulators (12%) were the most tested therapy. Two-thirds of studies only reported delivery or immediate neonatal outcomes. Adverse effects were rarely reported (11%). Most studies (73%), independent of the intervention, showed a benefit in fetal survival or birthweight. The risk of bias was high, mostly due to the lack of randomization, allocation concealment, and blinding. Future research should aim to describe both short- and long-term outcomes across various organ systems in well-characterized models. Further efforts must be made to reduce selection, performance, and detection bias.

Maternal Blood Fatty Acid Levels in Small and Adequate for Gestational Age Pregnancies

Background

The aim is to assess the levels of fatty acids (FAs) in pregnancies with small for gestational age (SGA) and adequate for gestational age (AGA) fetuses, constituting an association between FAs and fetal growth; according to the role of FA, lower levels were expected in SGA.

Materials and Methods

This was an analytical cross-sectional study including pregnant women with gestational ages of 26-36 weeks with AGA and constitutionally SGA fetuses diagnosed by ultrasonography. The levels of saturated, trans, monounsaturated, and polyunsaturated fatty acids were measured using centrifugation and liquid chromatography. Student's t test and general linear model using gestational age as covariant were used to compare the levels of FAs and the groups (AGA and SGA). Chi-square was used to evaluate the association between groups and studied variables. Pearson correlation coefficient and linear regression were used to evaluate the correlation between the levels of FAs and gestational age.

Results

Peripheral blood was collected from 67 pregnant women, 3 of whom were excluded from the study. No significant statistical differences were observed between SGA (n = 40) and AGA (n = 24) in relation to saturated, trans, monounsaturated, and polyunsaturated fatty acids (p > 0.05). There was not significant correlation between saturated, trans, monounsaturated, and polyunsaturated FAs and gestational age (p > 0.05).

Conclusion

The levels of saturated, trans, monounsaturated, and polyunsaturated FAs were similar in constitutionally SGA and AGA fetuses.

The association between dietary fatty acid intake and the risk of developing preeclampsia: a matched case-control study

The association between dietary fat intake during pregnancy and the risk of developing preeclampsia has been examined in many epidemiological studies, but the results remain inconsistent. The aim of this study was to clarify this association in pregnant Chinese women. After conducting 1:1 matching, 440 pairs consisting of pregnant women with preeclampsia and hospital-based, healthy pregnant women matched by gestational week (± 1 week) and age (± 3 years) were recruited. A 79-item semi-quantitative food frequency questionnaire administered during face-to-face interviews was used to estimate the participants’ dietary intake of fatty acids. We found that the intakes of arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) were inversely associated with the risk of developing preeclampsia. Compared with the lowest quartile intake, the multivariate-adjusted odds ratios (95% confidence interval) of the highest quartile intake were 0.42 (0.26–0.68, p-trend < 0.001) for EPA, 0.52 (0.3–0.83, p-trend = 0.005) for DHA, and 0.41 (0.19–0.88, p-trend = 0.007) for AA. However, we did not observe any significant associations between the intake of total fatty acids, saturated fatty acids, and mono-unsaturated fatty acids and the risk of developing preeclampsia. Our results showed that the dietary intake of long-chain polyunsaturated fatty acids (i.e., EPA, DHA, and AA) may protect pregnant Chinese women against the development of preeclampsia.

Omega-3 fatty acid supplement use and oxidative stress levels in pregnancy

Oxidative stress is a biological imbalance in reactive oxygen species and antioxidants. Increased oxidative stress during pregnancy has been associated with adverse birth outcomes. Omega-3 fatty acid (n-3 FA) supplementation may decrease oxidative stress; however, this relationship is seldom examined during pregnancy. This study assessed the association between n-3 FA supplement use during pregnancy and urinary oxidative stress biomarker concentrations. Data came from The Infant Development and the Environment Study (TIDES), a prospective cohort study that recruited pregnant women in 4 US cities between 2010-2012. Third trimester n-3 FA intake was self-reported. Third trimester urinary 8-iso-prostaglandin F2α (8-iso-PGF2α) was measured as an oxidative stress biomarker. Additionally, we measured the major metabolite of 8-iso-PGF2α and Prostaglandin F2α (PGF2α) and utilized the 8-iso-PGF2α to PGF2α ratio to calculate the change in 8-iso-PGF2α reflecting oxidative stress versus inflammation. Adjusted linear models were used to determine associations with control for confounding. Of 725 women, 165 reported n-3 FA supplement use in the third trimester. In adjusted linear models, n-3 FA use was associated with 10.2% lower levels of 8-iso-PGF2α (95% Confidence Interval [CI]: -19.6, 0.25) and 10.3% lower levels of the metabolite (95% CI: -17.1, -2.91). No associations were observed with PGF2α. The lower levels of 8-iso-PGF2α appeared to reflect a decrease in oxidative stress (percent change with supplement use: -18.7, 95% CI: -30.1, -5.32) rather than inflammation. Overall, third trimester n-3 FA intake was associated with lower concentrations of 8-iso-PGF2α and its metabolite, suggesting a decrease in maternal oxidative stress during pregnancy.

Distribution of Fatty Acids and Lipids During Pregnancy

Maternal fatty acid and lipid metabolism undergoes changes during pregnancy to facilitate fetal growth and development. Different types of fatty acids have different roles in maintaining a successful pregnancy and they are incorporated into different forms of lipids for the purpose of storage and transport. This chapter aims to provide an understanding of the distribution and metabolism of fatty acids and lipids in the maternal, placental, and fetal compartments. We further describe how this distribution is altered in maternal obesity, preterm birth, and pregnancy complications such as gestational diabetes mellitus, preeclampsia, and intrauterine growth restriction.

Sexual dimorphism in the effect of maternal obesity on antioxidant defense mechanisms in the human placenta

INTRODUCTION

Maternal obesity creates an adverse intrauterine environment, negatively impacts placental respiration, is associated with a higher incidence of pregnancy complications and programs the offspring for disease in adult life in a sexually dimorphic manner. We defined the effect of maternal obesity and fetal sex on pro- and anti-oxidant status in placenta and placental mitochondria.

METHODS

Placental villous tissue was collected at term via c-section prior to labor from four groups of patients based on fetal sex and prepregnancy/1st trimester body mass index: lean - BMI 22.1 ± 0.3 (6 male, 6 female) and obese - BMI 36.3 ± 0.4 (6 male, 6 female). Antioxidant enzyme activity, mitochondrial protein carbonyls, nitrotyrosine residues, total and nitrated superoxide dismutase (SOD) and nitric oxide synthesis were measured.

RESULTS

Maternal obesity was associated with decreased SOD and catalase activity, and total antioxidant capacity (TAC), but increased oxidative (protein carbonyls) and nitrative (nitrotyrosine) stress in a sexually dimorphic manner. Placentas of lean women with a male fetus had higher SOD activity and TAC (p < 0.05) than other groups whereas obese women with a male fetus had highest carbonyls and nitrotyrosine (p < 0.05). Glutathione peroxidase and thioredoxin reductase activity increased with obesity, significantly with a male fetus, perhaps as a compensatory response.

CONCLUSION

Maternal obesity affects oxidative stress and antioxidant activity in the placenta in a sexually dimorphic manner. The male fetus of a lean women has the highest antioxidant activity, a protection which is lost with obesity perhaps contributing to the increased incidence of adverse outcomes with a male fetus.

Neuroinflammation in Autism: Plausible Role of Maternal Inflammation, Dietary Omega 3, and Microbiota

Several genetic causes of autism spectrum disorder (ASD) have been identified. However, more recent work has highlighted that certain environmental exposures early in life may also account for some cases of autism. Environmental insults during pregnancy, such as infection or malnutrition, seem to dramatically impact brain development. Maternal viral or bacterial infections have been characterized as disruptors of brain shaping, even if their underlying mechanisms are not yet fully understood. Poor nutritional diversity, as well as nutrient deficiency, is strongly associated with neurodevelopmental disorders in children. For instance, imbalanced levels of essential fatty acids, and especially polyunsaturated fatty acids (PUFAs), are observed in patients with ASD and other neurodevelopmental disorders (e.g., attention deficit hyperactivity disorder (ADHD) and schizophrenia). Interestingly, PUFAs, and specifically n-3 PUFAs, are powerful immunomodulators that exert anti-inflammatory properties. These prenatal dietary and immunologic factors not only impact the fetal brain, but also affect the microbiota. Recent work suggests that the microbiota could be the missing link between environmental insults in prenatal life and future neurodevelopmental disorders. As both nutrition and inflammation can massively affect the microbiota, we discuss here how understanding the crosstalk between these three actors could provide a promising framework to better elucidate ASD etiology.

The effect of n-3 LCPUFA supplementation on oxidative stress and inflammation in the placenta and maternal plasma during pregnancy

Pregnancy represents a state of heightened oxidative stress and inflammation, and these processes are further increased in pregnancy complications. The quality of the maternal diet is directly associated with maternal health and wellbeing, pregnancy and fetal outcomes, as well as the risk of pregnancy complications. Long chain polyunsaturated fatty acids (LCPUFAs) have significant potential to modify placental and fetal lipid environments and thereby modulate health outcomes. The omega-3 (n-3) LCPUFA in particular have been shown to exhibit both antioxidant and anti-inflammatory properties, and have potential therapeutic applications in reducing oxidative damage and inflammation during pregnancy. The purpose of this review is to provide an overview of our current understanding of the impact of maternal n-3 LCPUFA supplementation on oxidative stress and inflammation during pregnancy, with a particular focus on effects on the mother and the placenta.

Omega-3 supplementation during pregnancy to prevent recurrent intrauterine growth restriction: systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

To evaluate the efficacy of omega-3 supplementation during pregnancy in preventing intrauterine growth restriction (IUGR) in women with apparently uncomplicated singleton pregnancy and previous IUGR pregnancy.

METHODS

For this systematic review, the research protocol was designed a priori. Searches were performed in electronic databases for studies published from inception of each database to December 2014. A combination of search terms was used including 'fish oil', 'long chain polyunsaturated fatty acids', 'intrauterine growth restriction', 'small for gestational age' and 'omega-3'. We included all randomized controlled trials (RCTs) of women with an uncomplicated singleton pregnancy and a prior IUGR pregnancy who were randomized to receive prophylactic treatment with omega-3 supplementation or either placebo or no treatment (control). Trials that included women with multiple gestations and those with only biochemical outcomes available were excluded. Pooled estimates were based on relative risk (RR) with 95% CI. Primary outcome was incidence of IUGR as defined in the RCTs.

RESULTS

Three RCTs including 575 women with uncomplicated singleton pregnancy with prior IUGR were analyzed. Women who received omega-3 supplementation during pregnancy had the same incidence of IUGR, defined as estimated fetal weight < 5(th) or < 3(rd) centiles, as had controls (22.8% vs 20.2%, respectively; RR, 1.13 (95% CI, 0.83-1.54)). Compared to controls, women who received omega-3 supplementation delivered later (mean difference, 1.4 (95% CI, 1.28-1.63) weeks), had a longer latency (mean difference, 2 (95% CI, 1.73-2.08) weeks), had a similar incidence of perinatal death (2.1% vs 3.3%, respectively; RR, 0.60 (95% CI, 0.15-2.42)) and similar birth weight (mean difference, 50 g (95% CI, -26 to 246 g)).

CONCLUSIONS

Omega-3 supplementation during pregnancy does not prevent recurrence of IUGR in women with uncomplicated singleton pregnancy and a previous IUGR pregnancy.

Maternal micronutrients, omega-3 fatty acids, and placental PPARγ expression

An altered one-carbon cycle is known to influence placental and fetal development. We hypothesize that deficiency of maternal micronutrients such as folic acid and vitamin B12 will lead to increased oxidative stress, reduced long-chain polyunsaturated fatty acids, and altered expression of peroxisome proliferator activated receptor (PPARγ) in the placenta, and omega-3 fatty acid supplementation to these diets will increase the expression of PPARγ. Female rats were divided into 5 groups: control, folic acid deficient, vitamin B12 deficient, folic acid deficient + omega-3 fatty acid supplemented, and vitamin B12 deficient + omega-3 fatty acid supplemented. Dams were dissected on gestational day 20. Maternal micronutrient deficiency leads to lower (p < 0.05) levels of placental docosahexaenoic acid, arachidonic acid, PPARγ expression and higher (p < 0.05) levels of plasma malonidialdehyde, placental IL-6, and TNF-α. Omega-3 fatty acid supplementation to a vitamin B12 deficient diet normalized the expression of PPARγ and lowered the levels of placental TNF-α. In the case of supplementation to a folic acid deficient diet it lowered the levels of malonidialdehyde and placental IL-6 and TNF-α. This study has implications for fetal growth as oxidative stress, inflammation, and PPARγ are known to play a key role in the placental development.

Maternal dietary omega-3 fatty acids and placental function

The developing fetus requires substantial amounts of fatty acids to support rapid cellular growth and activity. Although the fatty acid composition delivered to the fetus is largely determined by maternal circulating levels, the placenta preferentially transfers physiologically important long-chain polyunsaturated fatty acids (LC-PUFAs), particularly omega-3 (n-3) PUFAs. Maternal dietary supplementation with n-3 PUFAs during pregnancy has been shown to increase gestation length, enhance fetal growth, and reduce the risk of pregnancy complications, although the precise mechanisms governing these effects remain uncertain. Omega-3 PUFAs are involved in several physiological pathways which could account for these effects, including anti-inflammatory, pro-resolving, and anti-oxidative pathways. Recent studies have shown that maternal dietary n-3 PUFA supplementation during rat pregnancy can reduce placental oxidative damage and increase placental levels of pro-resolving mediators, effects associated with enhanced fetal and placental growth. Because several placental disorders, such as intrauterine growth restriction, preeclampsia, and gestational diabetes mellitus, are associated with heightened placental inflammation and oxidative stress, there is considerable interest in the potential for dietary n-3 PUFAs as a therapeutic intervention for these disorders. In this study, we review the impact of dietary n-3 PUFAs on placental function, with particular focus on placental inflammation, inflammatory resolution, and oxidative stress.