Placental expression of miR-21-5p, miR-210-3p and miR-141-3p: relation to human fetoplacental growth

BACKGROUND/OBJECTIVES

Dysregulation of microRNAs (miRNAs) and their target genes in placental tissue is associated with foetal growth restriction. We aimed to evaluate associations of placental miR-21-5p, miR-141-3p and miR-210-3p expression with maternal, placental and newborn parameters and with placental expression of their potential target genes PTEN, VEGF, FLT and ENG in a set of well-characterized small- (SGA) and appropriate- (AGA) for gestational age full-term singleton pregnancies.

SUBJECTS/METHODS

Placental samples (n = 80) from 26 SGA and 54 AGA were collected from full-term singleton pregnancies. Placental transcript abundances of miR-21-5p, miR-141-3p and miR-210-3p were assessed after normalization to a reference miRNA, mir-16-5p by real-time quantitative PCR. Placental transcript abundances of PTEN, VEGF, FLT and ENG were assessed after normalizing to a panel of reference genes.

RESULTS

Placental miR-21-5p transcript abundance was negatively associated with placental weight (n = 80, r = -0.222, P = 0.047) and this association was specific to the AGA births (n = 54, r = -0.292, P = 0.032). Placental transcript abundances of miR-210-3p and miR-141-3p were not associated with placental weight or birth weight in all 80 births. However, placental miR-210-3p transcript abundance was positively associated with birth weight specifically in the SGA births (n = 26, r = 0.449, P = 0.021). Placental transcript abundance of miR-21-5p was negatively associated with PTEN transcript abundance (Spearman's ρ = -0.245, P = 0.028) while that of miR-141-3p was positively associated with FLT (Spearman's ρ = 0.261, P = 0.019) and ENG (Spearman's ρ = 0.259, P = 0.020) transcript abundances in all 80 births.

CONCLUSION

We conclude that placental miR-21-5p and miR-210-3p may be involved in fetoplacental growth. However, this regulation is unlikely to be mediated through placental expression of PTEN, VEGF, FLT or ENG.

Placental expression of RNU44, RNU48 and miR-16-5p: stability and relations with fetoplacental growth

BACKGROUND/OBJECTIVES

The current study aimed to identify suitable reference miRNA for placental miRNA expression analysis in a set of well-characterized and fetal-sex balanced small- (SGA) and appropriate- (AGA) for gestational age full-term singleton pregnancies.

SUBJECTS/METHODS

In this retrospective study, placental samples (n = 106) from 35 SGA (19 male and 16 female) and 71 AGA (30 male and 41 female) full-term singleton pregnancies were utilized. Placental transcript abundance of three widely used reference miRNAs [miR-16-5p and Small nucleolar RNAs (snoRNAs) RNU44 and RNU48] were assessed by real-time quantitative PCR. Raw cycle threshold (C_t) analysis and RefFinder tool analysis were conducted for evaluating stability of expression of these miRNAs.

RESULTS

Raw C_t values of miR-16-5p were similar between SGA and AGA births (P = 0.140) and between male and female births within SGA (P = 0.159) and AGA (P = 0.060) births while that of RNU44 and RNU48 were higher in SGA births (P = 0.008 and 0.006 respectively) and in male births within the SGA group (P = 0.005) for RNU44 and in female births within the AGA group (P = 0.048) for RNU48. Across all 106 samples tested using the RefFinder tool, miR-16-5p and RNU44 were equally stable reference miRNAs.

CONCLUSION

We recommend miR-16-5p and RNU44 as suitable reference miRNAs for placental samples from settings similar to our study.

Placental expression of leptin: fetal sex-independent relation with human placental growth

OBJECTIVES

Leptin (LEP) is a vital placental hormone that is known to affect different aspects of placental function and fetal development. The present study aimed to determine the association of placental LEP transcript abundance with maternal, placental, and newborn parameters.

SUBJECTS/METHODS

In this retrospective case-control study, placental samples (n = 105) were collected from small (SGA) and appropriate (AGA) for gestational age full-term singleton pregnancies (n = 44 SGA and n = 61 AGA). Placental transcript abundance of LEP was assessed by real-time quantitative PCR after normalization to a reference gene panel. LEP methylation was measured using a quantitative MethyLight assay in a subset of samples (n = 54).

RESULTS

Placental LEP transcript abundance was negatively and significantly associated with placental weight (β = -3.883, P = 0.015). This association continued to be significant in the SGA group (β = -10.332, P = 0.001), both in female (β = -15.423, P = 0.021) and male births (β = -10.029, P = 0.007). LEP transcript abundance was not associated with LEP methylation levels (Spearman's ρ = 0.148, P = 0.287).

CONCLUSION

We conclude that placental upregulation of LEP is an integral and fetal sex-independent component of placental growth restriction, which can be potentially targeted through maternal dietary modifications to improve fetoplacental growth.

Placental expression of ENG, VEGF, and FLT: Gender-specific associations with maternal vitamin B12 status

OBJECTIVES

Adequate vitamin B₁₂ is a requisite during pregnancy and its deficiency is linked with increased risk for adverse outcomes, likely mediated by impaired placental angiogenesis. Thus, we aimed to test associations of maternal vitamin B₁₂ status with the placental expression of angiogenesis-associated genes ENG, VEGF, and FLT.

SUBJECTS/METHODS

In this retrospective case-control study, placental and maternal trimester 1 blood samples (n = 104) were collected from small for gestational age (SGA) and appropriate for gestational age (AGA) full-term singleton pregnancies. Maternal trimester 1 vitamin B₁₂ status was measured. Placentae and neonates were weighed at birth. Realtime quantitative PCR was performed to assess placental transcript abundance of ENG, VEGF, and FLT normalized to a panel of reference genes. Associations of placental transcript abundance of the genes with maternal trimester 1 vitamin B₁₂ status were evaluated.

RESULTS

Placental ENG transcript abundance associated negatively with maternal trimester 1 vitamin B₁₂ status (β = -0.461, P = 0.017, n = 104). This association was specific to the female births (β = -0.590, P = 0.014, n = 60). Placental VEGF transcript levels were negatively associated with maternal trimester 1 vitamin B₁₂ status only in the female births (β = -1.995, P = 0.029). Placental FLT transcript levels were not associated with maternal trimester 1 vitamin B₁₂ status.

CONCLUSION

Maternal trimester 1 vitamin B₁₂ status was associated negatively with placental ENG and VEGF expression predominantly in the female births. Therefore, we hypothesize that the placenta adapts to low maternal vitamin B₁₂ status by up-regulating angiogenic pathways in a gender-specific manner.

Fetal sex modifies the effect of maternal macronutrient intake on the incidence of small-for-gestational-age births: a prospective observational cohort study

Background

Maternal macronutrient intake is likely to play a pivotal role in fetoplacental growth. Male fetuses grow faster and their growth is more responsive to maternal size.

Objective

We assessed the role of fetal sex in modifying the effect of maternal macronutrient intake on the risk of small-for-gestational-age (SGA) birth.

Design

This was a prospective, observational cohort study of 2035 births from an urban South Asian Indian population. Maternal intakes of total energy and macronutrients were recorded by validated food-frequency questionnaires. The interaction of trimester 1 macronutrient intake with fetal sex was tested on the outcome of SGA births.

Results

The prevalence of SGA was 28%. Trimester 1 macronutrient composition was high in carbohydrate and low in fat (means ± SDs-carbohydrate: 64.6% ± 5.1%; protein: 11.5% ± 1.1%; and fat: 23.9% ± 4.4% of energy). Higher carbohydrate and lower fat consumption were each associated with an increased risk of SGA [adjusted OR (AOR) per 5% of energy (95% CI): carbohydrate: 1.15 (1.01, 1.32); fat: 0.83 (0.71, 0.97)] specifically among male births (males: n = 1047; females: n = 988). Dietary intake of >70% of energy from carbohydrate was also associated with increased risk (AOR: 1.67; 95% CI: 1.00, 2.78), whereas >25% of energy from fat intake was associated with decreased risk (AOR: 0.61; 95% CI: 0.41, 0.90) of SGA in male births.

Conclusions

Higher carbohydrate and lower fat intakes early in pregnancy were associated with increased risk of male SGA births. Therefore, we speculate that fetal sex acts as a modifier of the role of maternal periconceptional nutrition in optimal fetoplacental growth.

Maternal intake of milk and milk proteins is positively associated with birth weight: A prospective observational cohort study

BACKGROUND

A striking number of low birth weight (LBW) Indian babies are born annually. Previous studies have confirmed the positive association between milk intake and birth weight. However, the relations between protein and vitamin B₁₂ from milk and birth weight have not been systematically explored.

AIMS

We examined the relations between birth weight and maternal intake of milk, protein from milk and vitamin B₁₂ from milk.

METHODS

This prospective, observational cohort study was conducted in an urban South Indian hospital. The dietary intakes of milk and milk products were assessed using validated food frequency questionnaire and at delivery birth outcomes were measured. The relations between milk products, milk protein, and vitamin B₁₂ from milk with birth weight and gestational weight gain were assessed in 2036 births with first trimester dietary and delivery data.

RESULTS

Median consumption of milk products in the first trimester was 310 g·day^-1 and average birth weight was 2876 g. Birth weight was positively associated with intake of milk products and of % protein from milk products (%milk protein) in the first trimester [β = 86.8, 95% confidence interval (CI): 29.1, 144.6; β = 63.1, 95% CI: 10.8, 115.5; P < 0.001 for both]. Intake of milk products and of %milk protein in the third trimester was positively associated with gestational weight gain (GWG) between the second and third trimester (One-way ANOVA, P < 0.001 and = 0.001, respectively). Neither birth weight nor GWG were associated with %vitamin B₁₂ from milk products.

CONCLUSIONS

These findings indicate that intake of milk products in the first trimester and especially, protein from milk products is positively associated with birth weight in this South Asian Indian population.

Glucose kinetics and pregnancy outcome in Indian women with low and normal body mass indices

BACKGROUND/OBJECTIVES

Fetal energy demands are met from the oxidation of maternally supplied glucose and amino acids. During the fasted state, the glucose supply is thought to be met by gluconeogenesis. Underweight women with low body mass index (BMI) might be unable to adequately supply amino acids to satisfy the demands of gluconeogenesis.

SUBJECTS/METHODS

Glucose kinetics were measured during the first and second trimesters of pregnancy in 10 low-BMI and 10 normal-BMI pregnant women at the 12th hour of an overnight fast using a primed 6 h U-(13)C glucose infusion and was correlated to maternal dietary and anthropometric variables and birth weight.

RESULTS

Low-BMI mothers consumed more energy, carbohydrates and protein, had faster glucose production (R (a)) and oxidation rates in the first trimester. In the same trimester, dietary energy and carbohydrate correlated with glucose production, glycogenolysis and glucose oxidation in all women. Both groups had similar rates of gluconeogenesis in the first and second trimesters. Glucose R (a) in the second trimester was weakly correlated with the birth weight (r=0.4, P=0.07).

CONCLUSIONS

Maternal energy and carbohydrate intakes, not BMI, appear to influence glucose R (a) and oxidation in early and mid pregnancy.

In vivo arginine production and nitric oxide synthesis in pregnant Indian women with normal and low body mass indices

BACKGROUND/OBJECTIVES

Nitric oxide (NO) has been proposed as a mediator of vascular expansion during pregnancy. Inability to increase NO synthesis and/or production of its precursor, arginine, may be a contributor to pregnancy-induced hypertension or preeclampsia. Because maternal weight is associated with blood pressure and risk of preeclampsia during pregnancy, it may also influence arginine and/or NO production. The purpose of this study was to determine the in vivo arginine production and NO synthesis rate in pregnant women with normal (n=10) and low (n=10) body mass indices (BMIs).

SUBJECTS/METHODS

Arginine flux and NO synthesis rate were measured in the postabsorptive state with constant infusions of 15N2-arginine and 13C,2H4-citrulline. Plasma concentrations of arginine and NO metabolites were also measured. Kinetic parameters were correlated to maternal variables, gestational age, birth weight and blood pressure.

RESULTS

Endogenous arginine flux was significantly faster in the low-BMI compared with normal-BMI women in the first trimester (63.1+/-3.4 vs 50.2+/-2.0 micromol/kg per h, P<0.01), but not in the second. Plasma NO concentration was higher (44.7+/-5.3 vs 30.4+/-1.9 micromol/l, P=0.03) and its rate of synthesis trended faster in the low-BMI compared with normal-BMI group in the second trimester. Maternal weight and BMI were negatively correlated with arginine flux in both trimesters and NO synthesis in the second trimester.

CONCLUSIONS

These findings suggest, but do not prove, that maternal BMI may be a factor in the ability to produce NO during pregnancy and may be one way by which BMI influences blood pressure during pregnancy.

The effect of fish and omega-3 LCPUFA intake on low birth weight in Indian pregnant women

BACKGROUND

Inadequate consumption of fish could be a risk factor for low birth weight (LBW). This study assessed fish intake and omega-3 LCPUFA intake and status for their association with LBW in a cohort of urban, south Indian pregnant women.

SUBJECTS/METHODS

In a prospective cohort study, data on maternal fish intake and omega-3 LCPUFA intake and status of 676 women were obtained at baseline (first trimester), the second and third trimesters of pregnancy. Infant birth weight was measured immediately following hospital delivery. The dropout rate was 7.6%.

RESULTS

Fifty-six percent of the study women consumed fish with low daily median intakes (3.4, 4.1 and 3.8 g day(-1) at the three trimesters, respectively). Consequently, the median intakes of EPA and DHA during pregnancy were also low at 2.1 and 10.1 mg day(-1), respectively. EPA and DHA intakes were associated with their status in erythrocyte membrane phospholipids during pregnancy (r=0.40 and 0.36, r=0.34 and 0.32 and r=0.37 and 0.41, at the three trimesters, respectively, all P<0.001). Women who did not eat fish during the third trimester had a significantly higher risk of LBW (OR: 2.49, P=0.019). Similarly, low EPA intake during the third trimester had an association with a higher risk of LBW (OR: 2.75, P=0.011).

CONCLUSIONS

Among low fish-eating pregnant women, fish intake in the third trimester was closely associated with birth weight. Supplementation with omega-3 LCPUFA during pregnancy may have important implications for fetal development in India.

Anthropometry and body composition of south Indian babies at birth

OBJECTIVES

To assess the consequences on body composition of increasing birth weight in Indian babies in relation to reported values in Western babies, and to assess the relationship between maternal and neonatal anthropometry and body composition.

DESIGN

Prospective observational study.

SETTING

Bangalore City, India.

SUBJECTS

A total of 712 women were recruited at 12.5+/-3.1 weeks of gestation (mean+/-standard deviation, SD) and followed up until delivery; 14.5% were lost to follow-up. Maternal body weight, height, mid upper-arm circumference and skinfold thicknesses were measured at recruitment. Weight and body composition of the baby (skinfold thicknesses, mid upper-arm circumference, derived arm fat index and arm muscle index; AFI and AMI, respectively) were measured at birth in hospital.

RESULTS

The mean+/-SD birth weight of all newborns was 2.80+/-0.44 kg. Birth weight was significantly related to the triceps and subscapular skinfold thickness of the baby. In a small number of babies with large birth weight for gestational age, there was a relatively higher normalised AFI relative to AMI than for babies with lower or appropriate birth weight for gestational age. Maternal height and fat-free mass were significantly associated with the baby's length at birth.

CONCLUSIONS

Skinfold thicknesses in Indian babies were similar to those reported in a Western population with comparable birth weights, and the relationship of AFI to birth weight appeared to be steeper in Indian babies. Thus, measures to increase birth weight in Indian babies should take into account possible adverse consequences on body composition. There were no significant relationships between maternal anthropometry and body composition at birth on multivariate analysis, except for sum of the baby's skinfold thicknesses and maternal fat-free mass (P<0.02).

Low maternal vitamin B12 status is associated with intrauterine growth retardation in urban South Indians

OBJECTIVE

To assess the maternal sociodemographic, anthropometric, dietary and micronutrient status in apparently healthy pregnant women in order to determine their associations with intrauterine growth retardation (IUGR).

DESIGN

Prospective observational study.

SETTING

Bangalore City, India.

SUBJECTS

A total of 478 women were recruited at 12.9+/-3.3 weeks of gestation and followed up at the first, second and third trimesters of pregnancy and at delivery. The dropout rate was 8.5%.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Birth weight was measured at hospital delivery.

RESULTS

The mean birth weight was 2.85+/-0.45 kg. In all, 28.6% of newborns were IUGR. There was a strong inverse relationship between maternal educational level and risk of IUGR. A low body weight at baseline was also associated with a high risk of IUGR. Compared with women in the highest quartile for second trimester weight gain, those in the lowest quartile had a significantly higher adjusted odds ratio (AOR: 3.98; 95% CI: 1.83, 8.65) for IUGR. Women in the lowest tertile for serum vitamin B(12) concentration during each of the three trimesters of pregnancy had significantly higher risk of IUGR (AOR: 5.98, 9.28 and 2.81 for trimesters 1-3, respectively).

CONCLUSIONS

The present study demonstrates associations between educational status, maternal weight and gestational weight gain with IUGR. Importantly, in a subsample, there were strong associations of vitamin B(12) status with IUGR, suggesting that better socioeconomic conditions, improved nutritional status and early detection of vitamin B(12) deficiency in pregnancy combined with appropriate interventions are likely to play an important role in reducing IUGR.

The relationship of neonatal serum vitamin B12 status with birth weight

Earlier studies have shown a relationship between maternal vitamin B12 status and birth weight. This study extends those findings directly in terms of neonatal vitamin B12 status and birth weight. One hundred and twelve women were followed from the first trimester of pregnancy and maternal blood was obtained in all three trimesters along with cord blood at birth of their neonates. The maternal and cord serum vitamin B12 concentrations were examined in relation to birth weight. There was a significant correlation between vitamin B12 concentration in maternal antenatal serum during each of the trimesters of pregnancy and cord serum (all P< 0.01). Neonates that were born with lower birth weights (categories of <2500 g and 2500-2999g) had significantly lower mean cord serum vitamin B12 concentrations when compared to those who were > or = 3000g (P = 0.02 and P = 0.05 respectively). A similar, however, non significant trend was observed for antenatal vitamin B12 concentrations at first and third trimesters. Cord serum vitamin B12 concentrations were significantly correlated with birth weight, up to 40 weeks of pregnancy (r=0.28, P=0.01) but not beyond that (> or =40 weeks gestation). Vitamin B12 status in the mother was related to neonatal vitamin B12 status as measured by cord serum vitamin B12 concentration. In addition, low neonatal vitamin B12 concentrations were adversely associated with low birth weights.