The relationship between maternal anemia and umbilical cord oxygen content at delivery

Maternal levels of care during pregnancy influence labor and delivery outcomes - present practices and future priorities

Neonatal encephalopathy (NE) is a diagnosis that is usually unexpected. Though there are many risk factors for the condition and multiple theories as to its genesis, the majority of cases cannot be predicted prior to the occurrence of the clinical syndrome. Indeed, it is common for a pregnant person to have multiple risk factors and a completely healthy child. Conversely, people with seemingly no risk factors may go on to have a profoundly affected child. In this synopsis we review risk factors, potential mechanisms for encephalopathy, the complicated issue of choosing which morbidity to take on and how the maternal level of care may influence outcomes. The reader should be able to better understand the limitations of current testing and the profound levels of maternal intervention that have been undertaken to prevent or mitigate the rare, but devastating occurrence of NE. Further, we suggest candidate future approaches to prevent the occurrence, and decrease the severity of NE. Any future improvements in the NE syndrome cannot be achieved via obstetric intervention and management alone or conversely, by improvements in treatments offered post-birth. Multidisciplinary approaches that encompass prepregnancy health, pregnancy care, intrapartum management and postpartum care will be necessary.

Prevalence and Risk Factors for Newborn Anemia in Southwestern Uganda: A Cross-Sectional Study

Introduction

The global prevalence of maternal anemia is about 42%, and in sub-Saharan Africa, the prevalence of newborn anemia ranges from 25% to 30%. Anemia in newborn babies may cause complications such as delayed brain maturation and arrested growth. However, there is limited data on the prevalence of newborn anemia and its risk factors in people living in resource-limited settings.

Objectives

We determined the prevalence and risk factors for newborn anemia and its correlation with maternal anemia in southwestern Uganda.

Methods

This was a cross sectional study of 352 pregnant women presenting to the Mbarara Regional Referral Hospital for delivery. We collected maternal blood in labor and umbilical cord blood from the placental vein. We measured hemoglobin using a point-of-care Hemocue machine. We used summary statistics to characterize the study participants and compared demographic characteristics and outcomes using chi-square, t-test, and Wilcoxon rank sum analyses. We defined newborn anemia as umbilical cord hemoglobin <13 g/dl and measured the relationship between maternal and umbilical cord hemoglobin using linear regression analysis.

Results

The prevalence of newborn anemia was 17%. Maternal parity was significantly higher for anemic than nonanemic newborns (3 versus 2, P=0.01). The mean age in years (SD) was significantly lower for participants with umbilical cord hemoglobin <13 g/dl than those ≥13 g/dl (26 years [5.6] versus 28 [6.3], P=0.01). In multivariable linear regression analysis, a 1-point decrease in maternal hemoglobin was associated with a 0.14-point decrease in umbilical cord hemoglobin (P=0.02). Each one-unit increase in parity was associated with a 0.25-point decrease in umbilical cord hemoglobin (P=0.01). Cesarean delivery was associated with a 0.46-point lower umbilical cord hemoglobin level compared with vaginal delivery (P=0.03).

Conclusions

We found a significant association between maternal and newborn hemoglobin, underscoring the importance of preventing and correcting maternal anemia in pregnancy. Furthermore, maternal anemia should be considered a risk factor for neonatal anemia.

The relationship between maternal anemia and electronic fetal monitoring patterns

BACKGROUND

Anemia is a commonly diagnosed comorbidity in pregnancy that is associated with increased risk of maternal and neonatal complications. Recent data demonstrate that maternal anemia is associated with higher umbilical artery and umbilical vein O2 content at the time of delivery.

OBJECTIVE

This study aimed to examine the relationship between maternal anemia and electronic fetal monitoring patterns associated with fetal hypoxia.

STUDY DESIGN

This is a secondary analysis of a prospective cohort study of singleton term deliveries with cord gases and universal complete blood count collected on admission between 2010 and 2014. Maternal anemia was defined as hemoglobin ≤11.0 g/dL on admission. The primary outcome was a composite of high-risk category 2 electronic fetal monitoring features in the last 60 minutes before delivery (recurrent late and/or variable decelerations, minimal variability, tachycardia, or >1 prolonged deceleration); secondary outcomes were total deceleration area and total deceleration area >90th percentile. Of the 8580 patients in the original study, 8196 were included in the analysis. Outcomes were compared between patients with and without anemia. Multivariable logistic regression was used to adjust for potentially confounding factors, including hypertensive disorders of pregnancy and induction of labor.

RESULTS

Of the 8196 patients with complete blood count on admission and fetal monitoring data, 2672 (32.6%; 2672/8196) were anemic and 5524 (67.4%; 5524/8196) were not. Patients with anemia were significantly less likely to have composite high-risk category 2 features on electronic fetal monitoring (34.2% vs 32.0%; adjusted risk ratio, 0.93; 95% confidence interval, 0.86-0.99). Women with anemia also had decreased total deceleration area and were less likely to have total deceleration area >90th percentile (18.7% vs 16.2%; adjusted risk ratio, 0.85; 95% confidence interval, 0.77-0.94).

CONCLUSION

Patients with anemia are less likely to have high-risk category 2 electronic fetal monitoring features associated with fetal hypoxia. This finding is consistent with the association between maternal anemia and increased umbilical cord O2 content, and suggests that maternal anemia may be protective against intrapartum fetal hypoxia.

Blocked erythroid differentiation and delayed enucleation of erythroblasts may contribute to murine embryonic toxicity upon exposure to low dose of cadmium

Epidemiological and experimental studies have demonstrated the association of spontaneous abortion or embryonic atrophy with heavy metals, including some well-known anemia inducers, such as cadmium (Cd). However, the direct adverse effect of Cd on embryos without inducing maternal anemia remains unclear. In this study, we treated mice with a low dose of Cd before and after mating to minimize Cd-induced maternal anemia. Although most embryos developed normally, embryonic atrophy was still observed in a small percentage of embryos from Cd-exposed pregnant mice. Compared to the embryos from the control pregnant mice, a complete blockage of erythroid differentiation was observed in the atrophic embryos but no obvious alteration of erythroid differentiation in the non-atrophic embryos, respectively. Moreover, our results suggested delayed enucleation of erythroblasts in these non-atrophic embryos. Mechanically, the inhibited iron transport from the placenta to the fetus together with the increased iron export in the fetal livers might contribute to embryonic atrophy and delayed enucleation of erythroblasts upon Cd exposure. Our data may provide new insights into the embryonic toxicity of low-dose Cd.

Prenatal Hypoxia Affects Foetal Cardiovascular Regulatory Mechanisms in a Sex- and Circadian-Dependent Manner: A Review

Prenatal hypoxia during the prenatal period can interfere with the developmental trajectory and lead to developing hypertension in adulthood. Prenatal hypoxia is often associated with intrauterine growth restriction that interferes with metabolism and can lead to multilevel changes. Therefore, we analysed the effects of prenatal hypoxia predominantly not associated with intrauterine growth restriction using publications up to September 2021. We focused on: (1) The response of cardiovascular regulatory mechanisms, such as the chemoreflex, adenosine, nitric oxide, and angiotensin II on prenatal hypoxia. (2) The role of the placenta in causing and attenuating the effects of hypoxia. (3) Environmental conditions and the mother's health contribution to the development of prenatal hypoxia. (4) The sex-dependent effects of prenatal hypoxia on cardiovascular regulatory mechanisms and the connection between hypoxia-inducible factors and circadian variability. We identified that the possible relationship between the effects of prenatal hypoxia on the cardiovascular regulatory mechanism may vary depending on circadian variability and phase of the days. In summary, even short-term prenatal hypoxia significantly affects cardiovascular regulatory mechanisms and programs hypertension in adulthood, while prenatal programming effects are not only dependent on the critical period, and sensitivity can change within circadian oscillations.