Associations between genetically predicted iron status and cardiovascular disease risk: A Mendelian randomization study

Background

Mendelian randomization (MR) studies suggest a causal effect of iron (Fe) status on cardiovascular disease (CVD) risk, but it is unknown if these associations are confounded by pleiotropic effects of the instrumental variables (IV) on CVD risk factors. We aimed to investigate the effect of Fe status on CVD risk controlling for CVD risk factors.

Methods

Fe biomarker IVs (total Fe binding capacity (TIBC, n=208,422), transferrin saturation (TSAT, n=198,516), serum Fe (SI, n=236,612), ferritin (n=257,953)) were selected from a European GWAS meta-analysis. We performed two-sample univariate (UV) MR of each Fe trait on CVD outcomes (all-cause ischemic stroke (IS), cardioembolic IS (CES), large artery IS (LAS), small vessel IS (SVS), and coronary heart disease (CHD)) from MEGASTROKE (n=440,328) and CARDIoGRAMplusC4D (n=183,305). We then implemented multivariate (MV) MR conditioning on six CVD risk factors from independent European samples to evaluate their potential confounding and/or mediating effects on the observed Fe-CVD associations.

Results

With UVMR analyses, we found higher genetically predicted Fe status to be associated with a greater risk of CES (TSAT: OR 1.17 [95%CI 1.03, 1.33], SI: OR 1.21 [ 95%CI 1.02, 1.44]; TIBC: OR 0.81 [95%CI 0.69, 0.94]). The detrimental effects of Fe status on CES risk remained unaffected when adjusting for CVD risk factors (all P<0.05). Additionally, we found diastolic blood pressure (DBP) to mediate between 7.1-8.8% of the total effect of Fe status on CES incidence. While UVMR initially suggested a protective effect of Fe status on LAS and CHD, MVMR analyses factoring CVD risk factors revealed a complete annulment of this perceived protective effect (all P>0.05).

Discussion

Higher Fe status was associated with a greater risk of CES independent of CVD risk factors, and this effect was partly mediated by DBP. These findings support a role of Fe status as a modifiable risk factor for CES.

Placental ferroportin protein abundance is associated with neonatal erythropoietic activity and iron status in newborns at high risk for iron deficiency and anemia

BACKGROUND

Murine data suggest that the placenta downregulates ferroportin (FPN) when iron is limited to prioritize iron for its own needs. Human data on the impact of maternal and neonatal iron status on placental FPN expression are conflicting.

OBJECTIVES

This study aimed to identify determinants of placental FPN protein abundance and to assess the utility of the placental iron deficiency index (PIDI) as a measure of maternal/fetal iron status in newborns at high risk for anemia.

METHODS

Placental FPN protein abundance was measured by western blots in placentae collected from 133 neonates born to adolescents (17.4 ± 1.1 y) carrying singletons (delivery gestational age [GA]: 39.9 ± 1.3 wk) and from 130 neonates born to 65 females (30.4 ± 5.2 y) carrying multiples (delivery GA: 35.0 ± 2.8 wk). Placental FPN and the PIDI (FPN:transferrin receptor 1) were evaluated in relation to neonatal and maternal iron-related markers (hemoglobin [Hb], serum ferritin [SF], soluble transferrin receptor [sTfR], total body iron [TBI], hepcidin, erythropoietin [EPO], erythroferrone).

RESULTS

FPN protein was detected in all placentae delivered between 25 and 42 wk GA. Placental FPN protein abundance was associated with neonatal iron and erythropoietic markers (EPO: β: 0.10; 95% confidence interval [CI]: 0.06, 0.35; sTfR: β: 0.20; 95% CI: 0.03, 0.18; hepcidin: β: -0.06; 95% CI: -0.13, -0.0003; all P < 0.05). Maternal sTfR was only indirectly associated with placental FPN, with neonatal sTfR as the mediator (β-indirect: 0.06; 95% CI; 0.03, 0.11; P = 0.003). The PIDI was associated with neonatal Hb (β: -0.02; 95% CI: -0.03, -0.003), EPO (β: 0.07; 95% CI: 0.01, 0.14), and sTfR (β: 0.13; 95% CI: 0.004, 0.3) and with maternal SF (β: 0.08, 95% CI: 0.02, 0.14), TBI (β: 0.02; 95% CI: 0.009, 0.04), EPO (β: -0.10; 95% CI: -0.19, -0.01), sTfR (β: -0.16: 95% CI: -0.27, -0.06), and hepcidin (β: 0.05; 95% CI: 0.002, 0.11) at delivery (all P < 0.05).

CONCLUSIONS

Placental FPN abundance was positively associated with neonatal indicators of increased erythropoietic activity and poor iron status. The PIDI was associated with maternal and neonatal iron-related markers but in opposite directions. More data are needed from a lower-risk normative group of females to assess the generalizability of findings. These trials were registered at clinicaltrials.gov as NCT01019902 and NCT01582802.

Placental Erythroferrone and Erythropoietin mRNA Expression is not Associated with Maternal or Neonatal Iron Status in Adolescents Carrying Singletons and Adult Women Carrying Multiples

BACKGROUND

The iron regulatory hormones erythroferrone (ERFE), erythropoietin (EPO), and hepcidin, and the cargo receptor nuclear receptor coactivator 4 (NCOA4) are expressed in the placenta. However, determinants of placental expression of these proteins and their associations with maternal or neonatal iron status are unknown.

OBJECTIVES

To characterize expression of placental ERFE, EPO, and NCOA4 mRNA in placentae from newborns at increased risk of iron deficiency and to evaluate these in relation to maternal and neonatal iron status and regulatory hormones.

METHODS

Placentae were collected from 114 neonates born to adolescents carrying singletons (14-18 y) and 110 neonates born to 54 adults (20-46 y) carrying multiples. Placental EPO, ERFE, and NCOA4 mRNA expression were measured by RT-qPCR and compared with maternal and neonatal iron status indicators (SF, sTfR, total body iron, serum iron) and hormones.

RESULTS

Placental ERFE, EPO, and NCOA4 mRNA were detected in all placentae delivered between 25 and 42 wk of gestation. Relationships between placental ERFE and EPO differed by cohort. In the multiples cohort, placental EPO and ERFE were positively correlated (P = 0.004), but only a positive trend (P = 0.08) was evident in the adolescents. Placental EPO and ERFE were not associated with maternal or neonatal iron status markers or hormones in either cohort. Placental NCOA4 was not associated with placental EPO or ERFE in either cohort but was negatively associated with maternal SF (P = 0.03) in the multiples cohort and positively associated with neonatal sTfR (P = 0.009) in the adolescents.

CONCLUSIONS

The human placenta expresses ERFE, EPO, and NCOA4 mRNA as early as 25 wk of gestation. Placental expression of ERFE and EPO transcripts was not associated with maternal or neonatal iron status. Greater placental NCOA4 transcript expression was evident in women and newborns with poor iron status (lower SF and higher sTfR, respectively). Further research is needed to characterize the roles of these proteins in the human placenta.

TRIAL REGISTRATION NUMBER

These clinical trials were registered at clinicaltrials.gov as NCT01019902 (https://clinicaltrials.gov/ct2/show/NCT01019902) and NCT01582802 (https://clinicaltrials.gov/ct2/show/NCT01582802).

Mid-trimester uterine electromyography in patients with a short cervix

BACKGROUND

Preterm birth is the largest single cause of infant death in the United States. A cervical length of <2.5 cm, measured in the mid-trimester, has been shown to identify individuals at increased risk. Uterine electromyography is an emerging technology for noninvasively assessing uterine bioelectrical activity. With its ability to characterize nuanced differences in myometrial signals, uterine electromyography assessments during the mid-trimester may provide insight into the mechanisms of cervical shortening.

OBJECTIVE

This study aimed to characterize uterine bioelectrical activity in pregnant individuals with short cervices in the mid-trimester compared with that of pregnant individuals of the same gestational age with normal cervical lengths.

STUDY DESIGN

This is a prospective cohort study of subjects with singleton, nonanomalous pregnancies between 16 weeks and 0 days and 22 weeks and 6 days of gestational age. Subjects with normal cervical length (≥3.0 cm) were compared with subjects with short cervical length (<2.5 cm). The short-cervical-length cohort was further stratified by history of preterm birth. Multichannel uterine electromyography recordings were obtained for ∼60 minutes using proprietary, directional electromyography sensors on the abdomen. Uterine electromyography signals were observed and classified in groups as spikes, short bursts, and bursts. Primary outcomes were relative expression of spike, short-burst, and burst uterine electromyography signals. Subgroup analyses assessed each signal percentage by cervical length, history of preterm birth, and gestational age at delivery. Differences in percentage of uterine electromyography signals according to cervical length were analyzed using nonparametric tests of significance.

RESULTS

Of the 28 included subjects, 10 had normal and 18 had short cervical length. There were 9 subjects with short cervical length and a history of preterm birth. Spikes were the most commonly recorded signals and were higher in the normal-cervical-length cohort (96.3% [interquartile range, 93.1%-100.0%]) than the short-cervical-length cohort (75.2% [interquartile range, 66.7%-92.0%], P=.001). In contrast, median percentages of short-bursts and bursts were significantly higher in subjects with a short cervical length (17.3% [interquartile range, 13.6%-23.9%] vs 2.5% for normal cervical length [interquartile range, 0%-5.5%], P=.001 and 6.6% [interquartile range, 0%-13.4%] vs 0% for normal cervical length [interquartile range, 0%-2.8%], P=.014, respectively). Within subgroup analyses, cervical length was inversely proportional to percentage of observed short-bursts (P=.013) and bursts (P=.014). Subjects with short cervical length and history of preterm birth had higher burst percentages (12.8% [interquartile range, 9.0%-15.7%]) than those with short cervical length and no history of preterm birth (3.3% [interquartile range, 0%-5.0%], P=.003).

CONCLUSION

Short-burst and burst uterine electromyography signals are observed more frequently in mid-trimester patients with short cervical lengths. This relationship provides insight into abnormal myometrial activation in the mid-trimester and offers a plausible biophysiological link to cervical shortening.

Placental Iron Content Is Lower than Previously Estimated and Is Associated with Maternal Iron Status in Women at Greater Risk of Gestational Iron Deficiency and Anemia

BACKGROUND

Based on limited data, it is estimated that the placenta retains 90 mg of iron. Little is known about determinants of placental iron content. Animal data indicate that the placenta prioritizes iron for its own needs, but this hypothesis has not been evaluated in humans.

OBJECTIVES

To characterize placental iron content and placental iron concentration (p[Fe]) in pregnant women at risk of iron insufficiency and identify determinants of p[Fe].

METHODS

Placentas were collected from 132 neonates born to teens carrying singletons (≤18 y) and 101 neonates born to 48 women carrying multiples (20-46 y). Maternal and neonatal iron status indicators [hemoglobin, serum ferritin (SF), soluble transferrin receptor (sTfR), serum iron, total body iron (TBI)] and hormones (erythropoietin, hepcidin) were measured. p[Fe] was measured using inductively coupled plasma-mass spectrometry. Correlation analyses and mixed-effects models were constructed to identify determinants of p[Fe].

RESULTS

Mean placental iron content was 23 mg per placenta (95% CI: 15, 33 mg) in the multiples and 40 mg (95% CI: 31, 51 mg) in the teens (P = 0.03). Mean p[Fe] did not differ between the cohorts. p[Fe] was higher in anemic (175 μg/g; 95% CI: 120, 254 μg/g) compared with nonanemic (46 μg/g; 95% CI: 26, 82 μg/g) women carrying multiples (P = 0.009), but did not differ between anemic (62 μg/g; 95% CI: 40, 102 μg/g) and nonanemic (73 μg/g; 95% CI: 56, 97 μg/g) teens. In women carrying multiples, low maternal iron status [lower SF (P = 0.002) and lower TBI (P = 0.01)] was associated with higher p[Fe], whereas in teens, improved iron status [lower sTfR (P = 0.03) and higher TBI (P = 0.03)] was associated with higher p[Fe].

CONCLUSIONS

Placental iron content was ∼50% lower than previously estimated. p[Fe] is significantly associated with maternal iron status. In women carrying multiples, poor maternal iron status was associated with higher p[Fe], whereas in teens, improved iron status was associated with higher p[Fe]. More data are needed to understand determinants of p[Fe] and the variable iron partitioning in teens compared with mature women.

Vitamin D kinetics in nonpregnant and pregnant women after a single oral dose of trideuterated vitamin D3

The plasma pool of the hormone 1,25-dihydroxyvitamin D (1,25(OH)₂D) is increased throughout most of human pregnancy. Mechanisms behind this adaptation are unclear, in part due to limited data on vitamin D kinetics during pregnancy. Stable isotopes make it possible to study vitamin D kinetics in vulnerable study populations like pregnant women. We conducted a pilot study of vitamin D kinetics in nonpregnant and pregnant women. We evaluated a clinical protocol and developed analytical methods to assess the serum appearance and disappearance of trideuterated vitamin D₃ (d3-vitamin D₃) and trideuterated 25-hydroxyvitamin D₃ (d3-25(OH)D₃) after a single oral dose of 25 μg of [6,19,19-²H]-vitamin D₃ (d3-vitamin D₃). Blood was collected at baseline and 2, 4, 6, 24, 168, 264, and 456 hours post-dosing. We then described the serum kinetic profiles of d3-vitamin D₃ and d3-25(OH)D₃ in nonpregnant and pregnant women. Serum kinetic profiles of d3-vitamin D₃ and d3-25(OH)D₃ followed a time course in line with previous pharmacokinetic studies. There was marked variability between participants in the area under the concentration-time curve (AUC) of d3-25(OH)D₃ over the 20-day study period. This AUC of d3-25(OH)D₃ was positively correlated with the serum vitamin D binding protein (DBP) concentration, which was higher in pregnant compared with nonpregnant women. The mean serum half-life of 25(OH)D₃ was longer but not significantly different in pregnant women (18.8 days) compared with nonpregnant women (13.6 days). Our pilot study demonstrated that a single oral dose of 25 μg of d3-vitamin D₃ can be used to study vitamin D kinetics. Serum DBP concentration is an important predictor of vitamin D kinetics, and more research is needed to fully understand the significance of elevated DBP concentration during pregnancy.

Fetal iron uptake from recent maternal diet and the maternal RBC iron pool

BACKGROUND

During pregnancy iron can be obtained from the diet, body iron stores, or iron released from RBC catabolism. Little is known about the relative use of these sources to support fetal iron acquisition.

OBJECTIVES

To describe longitudinal change in iron absorption and enrichment across gestation and partitioning of RBC iron to the fetus.

METHODS

Fifteen pregnant women ingested an oral stable iron isotope (57Fe) in the second trimester (T2) of pregnancy (weeks 14-16) to label the RBC pool, and a second oral stable isotope (58Fe) in the third trimester (T3) (weeks 32-35). Absorption was measured at T2 and T3. Change in RBC 57Fe enrichment was monitored (18.8-26.6 wk) to quantify net iron loss from this pool. Iron transfer to the fetus was determined based on RBC 57Fe and 58Fe enrichment in umbilical cord blood at delivery.

RESULTS

Iron absorption averaged 9% at T2 and increased significantly to 20% (P = 0.01) by T3. The net increase in iron absorption from T2 to T3 was strongly associated with net loss in maternal total body iron (TBI) from T2 to T3 (P = 0.01). Mean time for the labeled RBC 57Fe turnover based on change in RBC enrichment was 94.9 d (95% CI: 43.5, 207.1 d), and a greater decrease in RBC 57Fe enrichment was associated with higher iron absorption in T2 (P = 0.001). Women with a greater decrease in RBC 57Fe enrichment transferred more RBC-derived iron to their fetus (P < 0.05).

CONCLUSIONS

Iron absorption doubled from T2 to T3 as maternal TBI declined. Women with low TBI had a greater decrease in RBC iron enrichment and transferred more RBC-derived iron to their neonate. These findings suggest maternal RBC iron serves as a significant source of iron for the fetus, particularly in women with depleted body iron stores.

Complications of Pregnancy in Adolescents

Teenage pregnancy is a complex issue that can have negative socioeconomic and health outcomes. About 11% of births worldwide are by adolescents aged between 15 and 19 years and middle- and low-income countries account for more than 90% of these births. Despite the downward trend in international adolescent pregnancy rates, 10 million unplanned adolescent pregnancies occur annually. Adolescents are also at increase risks of poor obstetric outcomes including preterm delivery, low birth weight, eclampsia, postpartum hemorrhage, anemia, and infant, as well as maternal morbidity. Important additional considerations include increased risk of depression, poor social support, and the need for a multidisciplinary approach to their obstetric care. We look to highlight both the unique socioeconomic and medical factors to consider when caring for these patients and demonstrate that these factors are intertwined.

Umbilical Cord Erythroferrone Is Inversely Associated with Hepcidin, but Does Not Capture the Most Variability in Iron Status of Neonates Born to Teens Carrying Singletons and Women Carrying Multiples

BACKGROUND

The developing fetus requires adequate iron and produces its own hormones to regulate this process. Erythroferrone (ERFE) is a recently identified iron regulatory hormone, and normative data on ERFE concentrations and relations between iron status and other iron regulatory hormones at birth are needed.

OBJECTIVES

The objective of this study was to characterize cord ERFE concentrations at birth and assess interrelations between ERFE, iron regulatory hormones, and iron status biomarkers in 2 cohorts of newborns at higher risk of neonatal anemia.

METHODS

Umbilical cord ERFE concentrations were measured in extant serum samples collected from neonates born to women carrying multiples (age: 21-43 y; n = 127) or teens (age: 14-19 y; n = 164). Relations between cord blood ERFE and other markers of iron status or erythropoiesis in cord blood were assessed by linear regression and mediation analysis.

RESULTS

Cord ERFE was detectable in all newborns delivered between 30 and 42 weeks of gestation, and mean concentration at birth was 0.73 ng/mL (95% CI: 0.63, 0.85 ng/mL). Cord ERFE was on average 0.25 ng/mL lower in newborns of black as opposed to white ancestry (P = 0.04). Cord ERFE was significantly associated with transferrin receptor (β: 1.17, P < 0.001), ferritin (β: -0.27, P < 0.01), and hemoglobin (Hb) (β: 0.04, P < 0.05). However, cord hepcidin and the hepcidin:erythropoietin (EPO) ratio captured the most variance in newborn iron and hematologic status (>25% of variance explained).

CONCLUSIONS

Neonates born to teens and women carrying multiples were able to produce ERFE in response to neonatal cord iron status and erythropoietic demand. ERFE, however, did not capture significant variance in newborn iron or Hb concentrations. In these newborns, cord hepcidin and the hepcidin:EPO ratio explained the most variance in iron status indicators at birth.

Serum Erythroferrone During Pregnancy Is Related to Erythropoietin but Does Not Predict the Risk of Anemia

BACKGROUND

Maintaining adequate iron status during pregnancy is important for the mother and her developing fetus. Iron homeostasis is influenced by 3 regulatory hormones: erythropoietin (EPO), hepcidin, and erythroferrone (ERFE). To date, normative data on ERFE across pregnancy and its relations to other hormones and iron status indicators are limited.

OBJECTIVES

The objective of this study was to characterize maternal ERFE across pregnancy and at delivery and evaluate the utility of hepcidin, ERFE, and EPO in identifying women with increased iron needs.

METHODS

ERFE was measured in extant serum samples collected from 2 longitudinal cohorts composed of women carrying multiple fetuses (n = 79) and pregnant adolescents (n = 218) at midgestation (∼26 wk) and delivery (∼39 wk). Receiver operating characteristic curves were generated to characterize the predictive ability of serum ERFE, hepcidin, and EPO and their ratios to identify women at increased risk of iron deficiency and anemia.

RESULTS

In these pregnant women, mean ERFE was 0.48 ng/mL at both ∼25 wk of gestation and at delivery. ERFE was positively associated with EPO at midgestation (β = 0.14, P = 0.002, n = 202) and delivery (β = 0.12, P < 0.001, n = 225) but was not significantly associated with maternal hepcidin at any time point surveyed. Of all hormones measured at midgestation and delivery, EPO was best able to identify women with anemia (AUC: 0.86 and 0.75, respectively) and depleted iron stores (AUC: 0.77 and 0.84), whereas the hepcidin-to-EPO ratio was best able to identify women with iron deficiency anemia (AUC: 0.85 and 0.84).

CONCLUSIONS

Maternal ERFE was significantly associated with EPO but was not able to identify women with gestational iron deficiency. At term, the hepcidin-to-EPO ratio, an index that accounts for both iron status and erythropoietic demand, and EPO were the strongest indicators of maternal iron deficiency and anemia. This trial was registered at clinicaltrials.gov as NCT04517734 (https://clinicaltrials.gov/ct2/show/NCT04517734).

Iron absorption during pregnancy is underestimated when iron utilization by the placenta and fetus is ignored

BACKGROUND

Maternal iron absorption during pregnancy can be evaluated using RBC incorporation of orally administered stable iron isotope. This approach underestimates true maternal absorption of iron as it does not account for absorbed iron that is transferred to the fetus or retained within the placenta.

OBJECTIVE

Our objective was to re-evaluate maternal iron absorption after factoring in these losses and identify factors associated with iron partitioning between the maternal, neonatal, and placental compartments.

METHODS

This study utilized data from stable iron isotope studies carried out in 68 women during the third trimester of pregnancy. Iron status indicators and stable iron isotopic enrichment were measured in maternal blood, umbilical cord blood, and placental tissue when available. Factors associated with iron isotope partitioning between the maternal, neonatal, and placental compartments were identified.

RESULTS

On average, true maternal absorption of iron increased by 10% (from 19% to 21%) after accounting for absorbed iron present in the newborn (P < 0.001), and further increased by 7%, (from 39% to 42%, P < 0.001) after accounting for iron retained within the placenta. On average, 2% of recovered tracer was present in the placenta and 6% was found in the newborn. Net transfer of iron to the neonate was higher in women with lower total body iron (standardized β = -0.48, P < 0.01) and lower maternal hepcidin (standardized β = -0.66, P < 0.01). In women carrying multiple fetuses, neonatal hepcidin explained a significant amount of observed variance in net placental transfer of absorbed iron (R = 0.95, P = 0.03).

CONCLUSIONS

Maternal RBC iron incorporation of an orally ingested tracer underestimated true maternal iron absorption. The degree of underestimation was greatest in women with low body iron. Maternal hepcidin was inversely associated with maternal RBC iron utilization, whereas neonatal hepcidin explained variance in net transfer of iron to the neonatal compartment.These trials were registered at clinicaltrials.gov as NCT01019096 and NCT01582802.

A social media intervention to improve nutrition knowledge and behaviors of low income, pregnant adolescents and adult women

Pregnant adolescents are at increased risk of adverse pregnancy outcomes compared to adult women, necessitating a need for early and comprehensive health care. This study aimed to evaluate the effectiveness of a social media intervention (i.e. weekly prenatal health messages) on improving diet quality, and health beliefs and knowledge. Participants (10 adolescents and 12 adults) completed pre-post intervention interviews, nutrition knowledge and health belief questionnaires, and 24-hour diet recalls. Participants entering pregnancy as overweight or obese were more likely to experience excessive GWG during the intervention. The adults had greater participation during the study despite high levels of social media access among both groups. Participants were able to identify sugar-sweetened foods and acknowledged the benefits of whole grains; however, overall knowledge of MyPlate Guidelines was limited. Social media-based education was well received by participants but did not result in large changes in dietary intake and knowledge. Although larger studies are needed, social media appears to have the potential to reach high-risk women.

Preterm Prelabor Rupture of Membranes: Outcomes with Expectant Management until 34 versus 35 Weeks

OBJECTIVE

To evaluate outcomes with expectant management of preterm prelabor rupture of membranes (PROM) until 35 weeks versus immediate delivery at ≥34 weeks.

STUDY DESIGN

This was a multicenter retrospective cohort study of singletons with preterm PROM at >20 weeks from 2011 through 2017. Groups were defined as expectant management until 35 weeks versus immediate delivery at ≥34 weeks. Primary outcome was composite neonatal morbidity: need for respiratory support, culture positive neonatal sepsis, or antibiotic administration for >72 hours. Univariate and general estimating equation models were used with p < 0.05 considered significant.

RESULTS

A total of 280 mother-infant dyads were included. There was no difference in composite neonatal outcome in pregnancies managed with expectant management compared with immediate delivery (43.4 vs. 37.5%; p = 0.32). Those with expectant management had shorter length of neonatal intensive care unit (NICU) admission but higher rates of neonatal antibiotics for > 72 hours, endometritis, and histological chorioamnionitis. There were no cases of fetal demise, neonatal death, or maternal sepsis, and only three cases of neonatal sepsis.

CONCLUSION

There is no difference in composite neonatal morbidity in pregnancies with preterm PROM managed with expectant management until 35 weeks as compared with immediate delivery at 34 weeks. Expectant management is associated with a decreased length of NICU admission but increased short-term infectious morbidity.

Does transvaginal ultrasound at 13-15 weeks improve anatomic survey completion rates in obese gravidas?

Objective: Obesity increases the difficulty of completing the fetal anatomic survey. This is of added concern in obese gravidas who are at higher risk of congenital fetal anomalies. We hypothesized that incorporation of an early transvaginal assessment could improve the completion rate of the fetal anatomic survey in obese women.Methods: We performed a prospective, longitudinal, blinded study of obese gravidas (BMI ≥ 35 kg/m²) comparing the use of a single early second trimester transvaginal ultrasound in addition to midtrimester transabdominal ultrasound versus traditional serial midtrimester ultrasound alone for completion of the anatomic survey. Transvaginal ultrasound for anatomy was performed between 13 0/7 and 15 6/7 week followed by midtrimester anatomic ultrasound, with each patient serving as her own control. Structures were marked as optimally or suboptimally viewed after each ultrasound. Sonographers and reviewers were blinded to images from the transvaginal ultrasound. Completion rates and gestational age at completion were compared between groups.Results: Fifty subjects were included. Fetal anatomic survey was completed in 62% using standard midtrimester assessment versus 78% with the addition of early transvaginal assessment (p = .04). The survey was completed at an earlier gestational age utilizing the transvaginal approach (22 0/7 ± 6 3/7) compared to traditional midtrimester transabdominal ultrasound approach (25 2/7 ± 5 3/7) p < .0005.Conclusions: Incorporation of an early transvaginal assessment of anatomy in obese women improved the rate of completion and led to earlier gestational age at completion of the fetal anatomic survey. Consideration should be given to including an early transvaginal sonogram as part of routine assessment of women with a BMI ≥ 35.

Umbilical Cord Serum Ferritin Concentration is Inversely Associated with Umbilical Cord Hemoglobin in Neonates Born to Adolescents Carrying Singletons and Women Carrying Multiples

BACKGROUND

It has been proposed that the fetus prioritizes iron for hemoglobin production over delivery to tissues. However, few studies have evaluated the interrelations between hemoglobin and multiple iron status biomarkers in umbilical cord blood. A full understanding is needed of how these parameters influence each other within cord blood to fully interpret iron and hematologic status at birth.

OBJECTIVES

We evaluated the determinants of neonatal hemoglobin and assessed the interrelations between hemoglobin, serum iron status indicators, and serum iron regulatory hormones in healthy neonates.

METHODS

This was an observational study that assessed umbilical cord hemoglobin (Hb), serum ferritin (SF), erythropoietin (EPO), soluble transferrin receptor (sTfR), serum iron, hepcidin, vitamin B-12, folate, IL-6, and CRP measured in 234 neonates born to adolescents or to women carrying multiples. Correlations between these indicators were evaluated and mediation models consistent with the observed significant determinants of cord Hb concentrations were developed.

RESULTS

A highly significant inverse association was found between cord SF and Hb concentrations that was not attributable to neonatal or maternal inflammation (as measured by IL-6 and CRP). The inverse association was present in the combined cohort, as well as in the adolescent and multiples cohorts independently. Mediation analyses found that EPO and hepcidin had significant indirect effects on cord Hb, associations that are explicable by mediation through SF and sTfR.

CONCLUSION

In contrast to observations made in older infants, a highly significant inverse association between Hb and SF, as well positive associations between Hb and both sTfR and EPO, were observed in umbilical cord blood from neonates born to adolescents or women carrying multiples. These findings, combined with review of the published literature, indicate a need for analysis of the relations between multiple parameters to assess iron and hematologic status at birth. These clinical trials were registered at clinicaltrials.gov as NCT01582802 (https://clinicaltrials.gov/ct2/show/NCT01582802) and NCT01019902 (https://clinicaltrials.gov/ct2/show/NCT01019902).

Vitamin B12 Status in Pregnant Adolescents and Their Infants

Vitamin B₁₂ deficiency has been associated with increased risk of adverse pregnancy outcomes. Few prospective studies have investigated the burden or determinants of vitamin B₁₂ deficiency early in life, particularly among pregnant adolescents and their children. The objectives of this study were to determine the prevalence of vitamin B₁₂ deficiency and to examine associations between maternal and neonatal vitamin B₁₂ status in a cohort study of healthy pregnant adolescents. Serum vitamin B₁₂ and folate concentrations were measured in adolescents at mid-gestation (n = 124; 26.4 ± 3.5 weeks) and delivery (n = 131; 40.0 ± 1.3 weeks), and in neonates at birth using cord blood. Linear regression was used to examine associations between maternal and neonatal vitamin B₁₂ status. Although the prevalence of vitamin B₁₂ deficiency (<148.0 pmol/L; 1.6%) in adolescents was low during pregnancy, 22.6% of adolescents were vitamin B₁₂ insufficient (<221.0 pmol/L; 22.6%) at mid-gestation. Maternal vitamin B₁₂ concentrations significantly decreased from mid-gestation to delivery (p < 0.0001), and 53.4% had insufficient vitamin B₁₂ status at delivery. Maternal vitamin B₁₂ concentrations (p < 0.001) and vitamin B₁₂ deficiency (p = 0.002) at delivery were significantly associated with infant vitamin B₁₂ concentrations in multivariate analyses, adjusting for gestational age, maternal age, parity, smoking status, relationship status, prenatal supplement use, pre-pregnancy body mass index, race, and intake of vitamin B₁₂ and folate. Maternal vitamin B₁₂ concentrations significantly decreased during pregnancy and predicted neonatal vitamin B₁₂ status in a cohort of healthy pregnant adolescents.

Longitudinal changes in serum vitamin D binding protein and free 25-hydroxyvitamin D in a multiracial cohort of pregnant adolescents

Serum free 25-hydroxyvitamin D (25(OH)D) rather than total 25(OH)D may better indicate vitamin D status during pregnancy given the pregnancy-associated increase in serum vitamin D binding protein (DBP) concentration. Our aims were to assess changes in DBP and free 25(OH)D across gestation and to determine whether free compared with total 25(OH)D more strongly correlates with markers of vitamin D and calcium metabolism during pregnancy. This ancillary study included 58 pregnant adolescents (53% African American, 47% White) who completed a vitamin D3 supplementation study in Rochester, NY. Blood was collected at entry, mid-study, and delivery (median 17, 29, and 40 weeks' gestation). Mixed-effects regression was used to test for differences in DBP, directly measured free 25(OH)D, and other serum markers by study visit and race. Free and total 25(OH)D were evaluated in relation to serum PTH, 1,25(OH)2D, 24,25(OH)2D, and calcium. The mean DBP concentration was above nonpregnant reference values at entry and increased across gestation (P < 0.0001). Total 25(OH)D explained most of the variance in free 25(OH)D (r ≥ 0.67; P < 0.0001). Holding total 25(OH)D constant, each 100 mg/L increase in DBP was associated with a 0.4 pg/mL decrease in free 25(OH)D (P < 0.01). The percent free 25(OH)D was inversely related to both DBP and total 25(OH)D at each visit. Regardless of race or visit, total 25(OH)D was a stronger correlate of PTH, 1,25(OH)2D, and 24,25(OH)2D, and neither total nor free 25(OH)D was related to serum calcium. African Americans had lower total 25(OH)D (P <  0.0001), but free 25(OH)D did not significantly differ by race (P =  0.2). In pregnant adolescents, DBP concentration was elevated and inversely associated with percent free 25(OH)D, but measured free 25(OH)D provided no advantage over total 25(OH)D as a predictor of PTH, 1,25(OH)2D, 24,25(OH)2D, or calcium. The clinical relevance of the small racial difference in percent free 25(OH)D requires further investigation.

Patterns and Correlates of Self-Reported Physical Activity in a Cohort of Racially Diverse Pregnant Adolescents

STUDY OBJECTIVE

Regular physical activity (PA) during pregnancy decreases the risk of gestational hypertension and preeclampsia. Currently, little is known about the PA of pregnant adolescents. Our intent was to characterize the PA behaviors of a group of racially diverse, low-income pregnant teens and to identify potential determinants of PA.

DESIGN, SETTING, PARTICIPANTS, AND INTERVENTIONS

A cohort of 157 racially diverse pregnant adolescents (13-18 years of age) completed up to 3 previous day PA recalls as part of a larger prospective longitudinal study on determinants of maternal and fetal bone health. Subjects self-reported activities from 7 AM to 11:30 PM, choosing from a list of 37 activities including a category for "other." Subjects recorded activities in 30-minute intervals.

MAIN OUTCOME MEASURES

Estimated metabolic equivalent task (MET) values were assigned to each activity and summed for a measure of total daily PA in MET min/d. Determinants of PA were evaluated using a stepwise linear mixed effect model.

RESULTS

The average calculated MET min/d was 1478 ± 130. Significant determinants of MET min/d included race (P = .007), maternal age at conception (P = .042), gestational age (P = .002), and attending school (P < .001). Black teens were less physically active than white teens, and older teens were more active than younger teens; activity decreased throughout gestation, and teens currently attending school were more active.

CONCLUSION

PA is low across gestation and pregnant teens spent more than half of their monitored time in sedentary activities. Targeted interventions are needed to achieve current PA goals in this pediatric obstetric population.

Umbilical Cord Hepcidin Concentrations Are Positively Associated with the Variance in Iron Status among Multiple Birth Neonates

Background

Hepcidin is a systemic regulator of iron homeostasis. Little is known about the relative role of maternal compared with cord hepcidin on neonatal iron homeostasis.

Objective

This study was undertaken to evaluate inter- and intrauterine variance in neonatal iron status, vitamin B-12, folate, and inflammatory markers in a cohort of twins (n = 50), triplets (n = 14), and quadruplets (n = 1) born to 65 women.

Methods

Umbilical cord blood was obtained from 144 neonates born at 34.8 ± 2.7 wk of gestation with a mean birth weight of 2236 ± 551 g (means ± SDs). Cord hemoglobin and cord serum measures of ferritin (SF), soluble transferrin receptor (sTfR), hepcidin, erythropoietin (EPO), iron, vitamin B-12, folate, interleukin 6, and C-reactive protein were evaluated.

Results

Intraclass correlation coefficient (ICC) analyses were used to examine inter- and intrauterine variance in neonatal iron indicators. A greater variability in cord hepcidin (ICC = 0.39) was found between siblings. Cord hepcidin had the greatest association with cord iron indicators because cord hepcidin alone captured 63.8%, 48.4%, 44.4%, and 31.3% of the intrauterine variance in cord hemoglobin, SF, sTfR, and EPO, respectively, whereas maternal hepcidin had no effect on cord iron indicators. Significantly greater differences in cord SF (P = 0.03), sTfR (P = 0.03), hepcidin (P = 0.0003), and EPO (P = 0.03) were found between di- and trichorionic siblings than between monochorionic siblings. In contrast, cord folate (ICC = 0.79) and vitamin B-12 (ICC = 0.74) exhibited a greater variability between unrelated neonates.

Conclusions

In summary, fetally derived hepcidin might have more control on intrauterine variance in iron indicators than maternal hepcidin and appears to be capable of regulating fetal iron status independently of maternal hepcidin. The use of a multiple-birth model provides a unique way to identify factors that may contribute to placental nutrient transport and iron stores at birth.

Gestational Age and Maternal Serum 25-hydroxyvitamin D Concentration Interact to Affect the 24,25-dihydroxyvitamin D Concentration in Pregnant Adolescents

Background

Interpretation of serum vitamin D biomarkers across pregnancy is complex due to limited understanding of pregnancy adaptations in vitamin D metabolism. During pregnancy, both gestational age and serum 25-hydroxyvitamin D [25(OH)D] concentrations may influence the concentrations of 1,25-dihydroxyvitamin D [1,25(OH)2D], 24,25-dihydroxyvitamin D [24,25(OH)2D], and parathyroid hormone (PTH).

Objective

We aimed to identify predictors of change in serum 25(OH)D across gestation in pregnant adolescents and to assess the contribution made by cholecalciferol (vitamin D3) supplementation. We sought to determine whether gestational age and 25(OH)D concentration interacted to affect serum 1,25(OH)2D, 24,25(OH)2D, or PTH.

Methods

Pregnant adolescents (n = 78, 59% African American, mean ± SD age: 17 ± 1 y) living in Rochester, NY (latitude 43°N) were supplemented with 200 IU or 2000 IU vitamin D3/d and allowed to continue their daily prenatal supplement that contained 400 IU vitamin D3. Serum was collected at study entry (18 ± 5 wk of gestation), halfway through study participation, and at delivery (40 ± 2 wk). Serum concentrations of the biochemical markers were modeled with linear mixed-effects regression models.

Results

Vitamin D3 supplement intake and season of delivery determined change in 25(OH)D across pregnancy. Fall-winter delivery was associated with a decline in 25(OH)D unless vitamin D3 supplement intake was >872 IU/d. The interaction of gestational age and 25(OH)D affected 24,25(OH)2D concentrations. For a given 25(OH)D concentration, model-predicted serum 24,25(OH)2D increased across gestation except when 25(OH)D was <13 ng/mL. Below this threshold, 24,25(OH)2D was predicted to decline over time. Mean serum 1,25(OH)2D was elevated (>100 pg/mL) throughout the study.

Conclusion

Our results suggest that when maternal serum 25(OH)D was low, its catabolism into 24,25(OH)2D decreased or remained stable as pregnancy progressed in order to maintain persistently elevated serum 1,25(OH)2D. Furthermore, in adolescents living at latitude 43°N, standard prenatal supplementation did not prevent a seasonal decline in 25(OH)D during pregnancy. This study was registered at clinicaltrials.gov as NCT01815047.

Elemental content of the placenta: A comparison between two high-risk obstetrical populations, adult women carrying multiples and adolescents carrying singletons

BACKGROUND

The placenta is responsible for the exchange of nutrients and for preventing harmful compounds from entering the fetal circulation. With increasing industrialization, exposures to commercial and toxic metals become a concern for both pregnant women and those planning a pregnancy. The understanding of transport mechanisms and pharmacokinetics for most inorganic elements is incomplete and limited to normal term deliveries.

OBJECTIVES

To obtain novel data on 46 inorganic elements in placentae from two high-risk obstetric populations, women carrying multiples and adolescents carrying singletons, evaluating differences, if present, and identifying predictors of placental content.

METHODS

Placental tissue was collected from adolescents carrying singletons and adults carrying multiples. Elemental content was analyzed using inductively coupled plasma-mass spectrometry (ICP-MS). Multivariate regression and factor analyses were used.

RESULTS

With the exception of Au and Pt, almost all placentae contained quantifiable concentrations of each element analyzed. All placentae contained the essential elements Ca, Fe, Mg, Se and Zn, which clustered together onto the same factor. Most elements were higher in placentae from women carrying multiples. Differences in placental content disappeared after adjusting for maternal age. Rare earth elements (REEs) clustered together and remained higher in the multiples even after adjusting for maternal age.

CONCLUSION

Human placentae contain a wide range of elements, including REEs. Ranges differed considerably between cohorts. Elements with similar chemical properties, like REEs or nutritionally essential elements, clustered together. Maternal age, and therefore longer environmental exposure, was significantly associated with elevated element concentrations in the placenta. Placental concentrations of several metals that are known to be nutritionally essential (e.g., Fe, Ca, Mg, and Zn) did not differ significantly between cohorts, suggesting tight regulation, whereas concentrations of environmental contaminants differed significantly between groups, even after adjusting for maternal age.

Low Vitamin D is Associated With Infections and Proinflammatory Cytokines During Pregnancy

Vitamin D is known to regulate innate and adaptive immune processes at the cellular level, but the role of vitamin D status on associated inflammatory processes across pregnancy is unclear. Our primary objective was to evaluate the relationships between serum biomarkers of inflammation (interleukin [IL]-6, IL-10, tumor necrosis factor [TNF]-α), acute-phase proteins (C-reactive protein and hepcidin) and vitamin D status, 25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D (1,25(OH)₂D), measured across pregnancy and in the neonate at birth. A second objective was to identify associations between vitamin D status and clinically diagnosed infections. In this study, 158 racially and ethnically diverse pregnant adolescents were recruited from the Rochester Adolescent Maternity Program (RAMP) in Rochester, NY. Serum 1,25(OH)₂D was significantly lower in adolescents and neonates with IL-6 concentrations above the 75th percentile at delivery ( P = .04) and at birth ( P = .004), respectively. After adjusting for other potential covariates of inflammation, maternal serum 1,25(OH)₂D was significantly positively associated with TNF-α during pregnancy ( P = .02), but at delivery 1,25(OH)₂D and TNF-α were inversely associated with one another ( P = .02). Teens with 25(OH)D concentrations <30 ng/mL were more likely to test positive for candida ( P = .002) and bacterial vaginosis ( P = .02) during pregnancy. African Americans exhibited significantly lower TNF-α concentrations at both mid-gestation ( P = .009) and delivery ( P = .001) compared to the Caucasian adolescents. These results suggest that lower maternal vitamin D status may increase risk of infection across gestation.

Vitamin D mediates the relationship between placental cathelicidin and group B streptococcus colonization during pregnancy

Vitamin D is thought to modulate innate immune responses, and recent studies have highlighted the autocrine and paracrine functions of vitamin D in the placenta. Our objective was to determine the relationship between maternal vitamin D status and placental antimicrobial peptide (AMP) expression in a group of racially and ethnically diverse pregnant adolescents. In this study, 158 pregnant adolescents were recruited from the Rochester Adolescent Maternity Program (RAMP) in Rochester, NY. Maternal serum concentrations of the vitamin D biomarkers, 25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D (1,25(OH)₂D), were measured at mid-gestation (∼26 weeks) and at delivery. At the placental level, vitamin D regulatory proteins (cubilin, megalin, 1α-hydroxylase (CYP27B1), 24-hydroxylase (CYP24A1), vitamin D receptor (VDR)) and AMPs (cathelicidin and hepcidin) were analyzed using quantitative PCR and western blot techniques. Placental CYP27B1 mRNA expression was significantly positively associated with both placental cathelicidin mRNA expression (P<0.0001) and placental hepcidin mRNA expression (P=0.002). In teens with positive recto-vaginal group B streptococcus (GBS) colonization, placental mRNA expression of cathelicidin (P=0.007), cubilin (P=0.03), and CYP27B1 (P=0.04) were significantly lower compared to those who tested negative for this infection. A mediation analysis showed that the indirect relationship between GBS colonization and placental cathelicidin mRNA expression was mediated by the placental mRNA expression of the vitamin D proteins cubilin and CYP27B1 (P=0.02). Additional research is needed to identify the role and relative contributions of placental and systemic vitamin D metabolites in relation to potentially pathogenic microorganisms which may be present during pregnancy.

Iron deficiency and anemia are prevalent in women with multiple gestations

BACKGROUND

Little attention has been placed on the unique iron demands that may exist in women with multiple gestations. This merits attention because iron deficiency (ID) during pregnancy is associated with adverse pregnancy outcomes that are known to be more prevalent in multiple births.

OBJECTIVE

We characterized longitudinal changes in iron status across pregnancy in a cohort of healthy women with multiple gestations and identified determinants of maternal ID and anemia.

DESIGN

A group of 83 women carrying twins, triplets, or quadruplets (aged 20-46 y) was recruited from 2011 to 2014. Blood samples obtained during pregnancy (∼24 wk; n = 73) and at delivery (∼35 wk; n = 61) were used to assess hemoglobin, serum ferritin (SF), soluble transferrin receptor (sTfR), hepcidin, serum iron, erythropoietin, serum folate, vitamin B-12, C-reactive protein, and interleukin-6.

RESULTS

The prevalence of tissue ID (sTfR >8.5 mg/L) increased significantly from pregnancy to delivery (9.6% compared with 23%, P = 0.03). Women with depleted iron stores (SF <12 μg/L, n = 20) during pregnancy had a 2-fold greater risk of anemia at delivery, and 25% (n = 5) developed iron deficiency anemia (IDA). Overall, 44.6% of women studied (n = 37/83) were anemic at delivery, and 18% of women (n = 11/61) had IDA. Erythropoietin during pregnancy was significantly negatively associated with hemoglobin at delivery. Women with erythropoietin >75th percentile during pregnancy exhibited a 3-fold greater risk of anemia, suggesting that erythropoietin is a sensitive predictor of anemia at delivery. Inflammation was present at delivery, which limited the utility of ferritin or hepcidin as iron-status indicators at delivery.

CONCLUSIONS

ID and anemia are highly prevalent in women with multiple gestations. Additional screening and iron supplementation may be warranted in this high-risk population given the known associations between ID anemia and adverse maternal and neonatal outcomes. This trial was registered at clinicaltrials.gov as NCT01582802.

Maternal iron status during pregnancy compared with neonatal iron status better predicts placental iron transporter expression in humans

The placenta richly expresses nonheme and heme Fe transport proteins. To address the impact of maternal and neonatal Fe status and hepcidin on the regulation of these proteins, mRNA expression and protein abundance of nonheme and heme Fe transport proteins were evaluated in placental tissue from 154 adolescents. Regression analyses found maternal Fe status was significantly associated with multiple placental nonheme and heme transporters, whereas neonatal Fe status was related to only 3 heme transporters. Across statistical analyses, maternal Fe status was consistently associated with the placental nonheme Fe importer transferrin receptor 1 (TfR1). Protein abundance of TfR1 was related to midgestation maternal serum ferritin (SF) (β = -0.32; P = 0.005) and serum TfR (β = 0.25; P = 0.024). Protein abundance of the heme importer, proton-coupled folate transporter, was related to neonatal SF (β = 0.30; P = 0.016) and serum TfR (β = -0.46; P < 0.0001). Neonatal SF was also related to mRNA expression of the heme exporter feline leukemia virus subgroup C receptor 1 (β = -0.30; P = 0.004). In summary, maternal Fe insufficiency during pregnancy predicts increased expression of the placental nonheme Fe transporter TfR1. Associations between placental heme Fe transporters and neonatal Fe status require further study.-Best, C. M., Pressman, E. K., Cao, C., Cooper, E., Guillet, R., Yost, O. L., Galati, J., Kent, T. R., O'Brien, K. O. Maternal iron status during pregnancy compared with neonatal iron status better predicts placental iron transporter expression in humans.

Shear Wave Elastography in the Living, Perfused, Post-Delivery Placenta

The placenta is the critical interface between the mother and the developing fetus and is essential for survival and growth. Despite the widespread use of ultrasound imaging and Doppler in obstetrics and gynecology and the recent growth of elastographic technologies, little is known about the biomechanical (elastic shear wave) properties of the placenta and the range of normal and pathologic parameters that are present. This study uses a well-developed protocol for perfusing whole placentas, post-delivery, to maintain tissue integrity and function for hours. In this model, the placenta is living, whole and maintained within normal physiologic parameters such as flow, arterial pressure and oxygen, throughout examination by ultrasound, Doppler and shear wave elastography. The preliminary results indicate that normal placental tissue on the fetal side has shear wave speeds on the order of 2 m/s, in a range similar to those of animal livers. Some abnormalities are found outside this range, and thus, elastographic measures of the placenta may provide useful assessments related to the state of the tissue.

The Effects of Trauma History and Prenatal Affective Symptoms on Obstetric Outcomes

Prenatal maternal mood may inform the adverse obstetric outcomes seen in disadvantaged populations. The contribution of having a trauma history is not well studied. We examined the impact of trauma exposure and mood symptoms on obstetric outcomes in 358 women. Women with antecedent trauma were more likely to have a history of depression, odds ratio = 2.83, 95% confidence interval [1.81, 4.42], were younger at their first pregnancy, 18.86 years versus 20.10 years, and had a higher number of previous pregnancies, 2.01 versus 1.54, compared to those with no trauma exposure. Women with prenatal anxiety had significantly smaller babies than nonanxious women, 3,313.17 g, (SD = 441.58) versus 3,429.27 g, (SD = 437.82) Trauma history magnified the effects of maternal prenatal mood on birthweight; the moderating effect was limited to those who first experienced a trauma under 18 years of age. Childhood trauma exposure increased vulnerability for low birthweight delivery associated with prenatal mood disturbance. Screening pregnant women for trauma history and current mood symptoms is indicated.

Vitamin D status is inversely associated with anemia and serum erythropoietin during pregnancy

BACKGROUND

Vitamin D and iron deficiencies frequently co-exist. It is now appreciated that mechanistic interactions between iron and vitamin D metabolism may underlie these associations.

OBJECTIVE

We examined interrelations between iron and vitamin D status and their regulatory hormones in pregnant adolescents, who are a group at risk of both suboptimal vitamin D and suboptimal iron status.

DESIGN

The trial was a prospective longitudinal study of 158 pregnant adolescents (aged ≤18 y). Maternal circulating biomarkers of vitamin D and iron were determined at midgestation (∼25 wk) and delivery (∼40 wk). Linear regression was used to assess associations between vitamin D and iron status indicators. Bivariate and multivariate logistic regressions were used to generate the OR of anemia as a function of vitamin D status. A mediation analysis was performed to examine direct and indirect relations between vitamin D status, hemoglobin, and erythropoietin in maternal serum.

RESULTS

Maternal 25-hydroxyvitamin D [25(OH)D] was positively associated with maternal hemoglobin at both midgestation and at delivery (P < 0.01 for both). After adjustment for age at enrollment and race, the odds of anemia at delivery was 8 times greater in adolescents with delivery 25(OH)D concentrations <50 nmol/L than in those with 25(OH)D concentrations ≥50 nmol/L (P <0.001). Maternal 25(OH)D was inversely associated with erythropoietin at both midgestation (P <0.05) and delivery (P <0.001). The significant relation observed between 25(OH)D and hemoglobin could be explained by a direct relation between 25(OH)D and hemoglobin and an indirect relation that was mediated by erythropoietin.

CONCLUSIONS

In this group of pregnant adolescents, suboptimal vitamin D status was associated with increased risk of iron insufficiency and vice versa. These findings emphasize the need for screening for multiple nutrient deficiencies during pregnancy and greater attention to overlapping metabolic pathways when selecting prenatal supplementation regimens.

Prepregnancy Body Mass Index and Gestational Weight Gain Have No Negative Impact on Maternal or Neonatal Iron Status

OBJECTIVE

To assess the impact of maternal obesity and excessive gestational weight gain (GWG) on maternal and neonatal iron status and to explore the possible mediating role of inflammation on hepcidin.

METHODS

This analysis included 230 pregnant adolescents (13-18 years) enrolled in either a longitudinal or a cross-sectional study. Prepregnancy body mass index (ppBMI) and GWG were obtained from medical records. Maternal iron status (hemoglobin, serum iron, ferritin, transferrin receptor, total body iron, and hepcidin) and inflammation (interleukin-6 [IL-6] and leptin) were assessed at midgestation (26.2 ± 3.3 weeks) in the longitudinal cohort and at delivery (39.8 ± 1.3 weeks) in both study cohorts. Cord blood was collected in both studies and analyzed for iron indicators.

RESULTS

Approximately 40% of the adolescents entered pregnancy overweight or obese. Multivariate analysis identified ppBMI as a negative predictor of serum iron at midgestation (P = .009) and a positive predictor of serum hepcidin at delivery (P = .02). None of the other maternal iron status indicators were significantly associated with ppBMI or GWG. Serum IL-6 was significantly positively associated with hepcidin at delivery (P = .0001) but not at midgestation. There was a positive relationship between ppBMI and cord hemoglobin (P = .03).

CONCLUSION

These results suggest that adiposity-related inflammation does not override the iron-mediated signals that regulate hepcidin production during pregnancy, and in this adolescent cohort, there is no strong evidence for a detrimental effect of maternal obesity and excessive weight gain on iron status in the offspring at birth.

Whole mount immunofluorescence analysis of placentas from normotensive versus preeclamptic pregnancies

INTRODUCTION

Defects in placental angiogenesis and spiral artery remodeling have been proposed to play essential roles in the development of preeclampsia. However, the specific molecular mechanism(s) responsible for aberrant placental angiogenesis in preeclampsia are incompletely understood. The vascular endothelial growth factor receptors (VEGFR1, R2, R3) and STAT3 have critical functions in normal blood vessel development, but their potential roles in preeclampsia are currently unclear. In this study, we utilized a novel whole mount immunofluorescence (WMIF) method to compare expression of VEGFR1, R2, R3 and activated, phosphorylated STAT3 (pSTAT3) in placentas of preeclamptic (PE) versus normotensive (NT) pregnancies.

METHODS

Placental biopsies collected from NT and PE pregnant women were fixed and stained with fluorochrome-conjugated antibodies to identify specific cell populations as follows: CD31 for blood vessel endothelial cells, cytokeratin-7 for trophoblast cells, and CD45 for immune cells. Expression of the VEGFRs and pSTAT3 were subsequently characterized by WMIF in conjunction with confocal microscopy.

RESULTS

A total of 18 PE and 18 NT placentas were evaluated. No significant differences in the cell type-specific expression patterns or expression levels of VEGFR1, VEGFR2 or VEGFR3 were detected between NT and PE placentas. In contrast, statistically significant increases in pSTAT3 staining were detected in endothelial cells of PE placentas versus NT controls.

DISCUSSION

Our study demonstrates that increased pSTAT3 expression in placental endothelial cells is associated with PE. We speculate that elevated pSTAT3 expression in the blood vessels of PE placentas may be due to aberrant angiogenesis, increased pro-inflammatory cytokine expression, and/or placental stress.

Maternal diet but not gestational weight gain predicts central adiposity accretion in utero among pregnant adolescents

BACKGROUND

Modifiable risk factors during pregnancy, such as diet and weight gain, are associated with fetal birth weight but little is known about how these factors influence fetal fat acquisition in utero among pregnant adolescents.

OBJECTIVE

To determine whether maternal pre-pregnancy BMI (ppBMI), gestational weight gain (GWG) and dietary intake during pregnancy influence fetal fat accretion in utero.

METHODS

Longitudinal data were obtained from 121 pregnant adolescents enrolled in a study designed to identify determinants of maternal and fetal bone changes across gestation. Adolescents (ages 13-18 years) completed up to three study visits during early, mid- and late gestation. Maternal anthropometrics, 24 h dietary recalls and measures of fetal biometry were obtained at each visit. Fetal abdominal wall thickness (abdominal subcutaneous fat thickness, AbFat), a measure of fetal subcutaneous fat, was calculated by sonography at each visit. Statistical determinants of AbFat during late pregnancy were explored using simple and multiple regression.

RESULTS

During late pregnancy (34.8±2.0 weeks; range 31.0-40.6 weeks of gestation), the median (inter-quartile range) fetal AbFat and GWG were 0.44 (0.39, 0.55) cm and 14.6 (9.5, 18.3) kg, respectively. After adjusting for infant birth weight, variables significantly associated with fetal AbFat included gestational age (P<0.0001, 95% confidence interval, CI: 0.01, 0.03), maternal race (P=0.029, 95% CI: -0.04, -0.002) and dietary intake of added sugar (P=0.025, 95% CI: 1.42e-6, 2.06e-5). Fetal AbFat had a significant positive quadratic relationship with total maternal dietary sugar intake such that both low and high extremes of sugar consumption were associated with significantly higher fetal AbFat. Birth weight was not significantly associated with maternal intake of added sugars.

CONCLUSION

Extreme sugar intakes among pregnant adolescents may lead to increased accumulation of fetal abdominal fat with little net effect on birth weight. This finding suggests that increased sugar consumption during pregnancy promotes shifts in fetal body composition.

Vitamin D Status Affects Serum Metabolomic Profiles in Pregnant Adolescents

Vitamin D is linked to a number of adverse pregnancy outcomes through largely unknown mechanisms. This study was conducted to examine the role of vitamin D status in metabolomic profiles in a group of 30 pregnant, African American adolescents (17.1 ± 1.1 years) at midgestation (26.8 ± 2.8 weeks), in 15 adolescents with 25-hydroxy vitamin D (25(OH)D) ≥20 ng/mL, and in 15 teens with 25(OH)D <20 ng/mL. Serum metabolomic profiles were examined using gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry. A novel hierarchical mixture model was used to evaluate differences in metabolite profiles between low and high groups. A total of 326 compounds were identified and included in subsequent statistical analyses. Eleven metabolites had significantly different means between the 2 vitamin D groups, after correcting for multiple hypothesis testing: pyridoxate, bilirubin, xylose, and cholate were higher, and leukotrienes, 1,2-propanediol, azelate, undecanedioate, sebacate, inflammation associated complement component 3 peptide (HWESASXX), and piperine were lower in serum from adolescents with 25(OH)D ≥20 ng/mL. Lower maternal vitamin D status at midgestation impacted serum metabolic profiles in pregnant adolescents.

Placental heme receptor LRP1 correlates with the heme exporter FLVCR1 and neonatal iron status

LDL receptor-related protein 1 (LRP1) is a transmembrane receptor highly expressed in human placenta. It was recently found to be the receptor for heme and its plasma-binding protein hemopexin (Hx) and is integral to systemic heme clearance. Little is known about systemic concentrations of Hx during pregnancy and whether maternal Hx and placental LRP1 contributes to fetal iron (Fe) homeostasis during pregnancy. We hypothesized that placental LRP1 would be upregulated in maternal/neonatal Fe insufficiency and would be related to maternal circulating Hx. Placental LRP1 expression was assessed in 57 pregnant adolescents (14-18 years) in relationship with maternal and cord blood Fe status indicators (hemoglobin (Hb), serum ferritin, transferrin receptor), the Fe regulatory hormone hepcidin and serum Hx. Hx at mid-gestation correlated positively with Hb at mid-gestation (r=0.35, P=0.02) and Hx at delivery correlated positively with cord hepcidin (r=0.37, P=0.005). Placental LRP1 protein expression was significantly higher in women who exhibited greater decreases in serum Hx from mid-gestation to term (r=0.28, P=0.04). Significant associations were also found between placental LRP1 protein with cord hepcidin (r=-0.29, P=0.03) and placental heme exporter feline leukemia virus C receptor 1 (r=0.34, P=0.03). Our data are consistent with a role for placental heme Fe utilization in supporting fetal Fe demands.

Placental CYP27B1 and CYP24A1 expression in human placental tissue and their association with maternal and neonatal calcitropic hormones

CONTEXT

Placental CYP27B1 may contribute to circulating maternal calcitriol concentrations across gestation, but determinants of CYP27B1 and CYP24A1 expression in term human placental tissue are not well established.

OBJECTIVE

We hypothesized that higher CYP27B1 protein expression would be associated with increased maternal calcitriol during gestation and that CYP27B1 expression would be impacted by substrate availability.

DESIGN

This was a prospective, longitudinal study.

SETTING

The study was completed in an urban, prenatal clinic located in Rochester, New York.

PATIENTS

The study was undertaken in a cohort of 70 pregnant adolescents (≤18 y of age) and their term neonates.

INTERVENTION

There was no intervention.

MAIN OUTCOMES

Protein and mRNA expressions of CYP27B1, CYP24A1, and vitamin D receptor were measured in term placental tissue and related to 25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyvitamin D, PTH, serum total calcium, IL-6, leptin, and osteoprotegerin measured in maternal serum at midgestation and delivery and in umbilical cord serum at birth.

RESULTS

Placental CYP27B1 protein expression was significantly positively associated with maternal 25(OH)D at both midgestation (n = 68, P = .009) and delivery (n=67, P = .006). Maternal serum 1,25-dihydroxyvitamin D concentrations at midgestation were positively correlated with term placental CYP27B1 mRNA expression (n = 49, P = .002). Significant positive associations were evident between placental CYP27B1 and CYP24A1 protein expression (P = .001, n = 70). Maternal PTH concentrations at midgestation or delivery did not significantly impact placental protein or transcript level of either enzyme. Variability in placental CYP27B1 protein expression was best captured by a model that included maternal midgestation 25(OH)D concentration, placental vitamin D receptor protein expression, and maternal midgestation IL-6 concentrations (P = .002, n = 60, R(2) = 0.22).

CONCLUSIONS

Higher maternal 25(OH)D during pregnancy was associated with significantly higher placental protein expression of CYP27B1 at term supportive of a link between substrate availability and placental production of calcitriol.

Diurnal cortisol patterns and psychiatric symptoms in pregnancy: short-term longitudinal study

Alteration in the HPA axis is a robust biomarker of anxiety and depression in adults, but questions remain about this association in pregnancy. We examined the longitudinal links between diurnal cortisol and mood symptoms from self-report questionnaire and diagnostic interview in an ethnically diverse, psychosocially at-risk sample of 101 women at mid-pregnancy and early third trimester. There were modest but significant associations between depression and elevated cortisol, indexed by a decreased morning level and diminished diurnal decline; the effects were strongest for diagnostic data from clinical interview. These effects were independent of socio-demographic factors and sleep disturbance. Associations with anxiety and trauma were generally non-significant. These findings extend prior work by showing that significant mood symptoms in pregnancy are associated with altered diurnal cortisol in pregnancy, which may have implications for maternal and child health.

Predictive role of prenasal thickness and nasal bone for Down syndrome in the second trimester

OBJECTIVE

To assess the efficacy of prenasal thickness (PNT) and nasal bone (NB) for prediction of Down syndrome (DS) fetuses in the second trimester ultrasound examination.

STUDY DESIGN

PNT was measured from stored two-dimensional fetal profile images taken at 15-23 weeks in 242 fetuses with normal karyotype (Group 1) and 24 fetuses with DS (Group 2). It was measured as the shortest distance from the anterior edge of the lowest part of the frontal bone to the skin. The efficacy of PNT, NB, PNT/NB and biparietal diameter (BPD)/NB was evaluated for prediction of DS.

RESULTS

PNT values increased with gestational age in normal fetuses. PNT measurement was ≥95th percentile in 54.2% (13/24) of the DS cases and 2.9% of the normal cases. Receiver operator curve analysis showed that PNT/NB ratio had the best area under the curve with a detection rate of 80% for a false positive rate of 5% at a cut-off value of 0.76.

CONCLUSIONS

PNT is increased in fetuses with DS as compared to normal fetuses. PNT/NB≥0.76 in the second trimester is a better predictor of DS than the use of PNT or NB alone.