Plasma Concentrations of N-Terminal Pro-B-Type Natriuretic Peptide in Pregnant Women near Labor and during Early Puerperium

Variations in NT-proBNP Levels in Pregnant Patients with and without SARS-CoV-2 Infection: Consequences for the Newborns

BACKGROUND

NT-proBNP (N-terminal pro-brain natriuretic peptide) has a high negative predictive value for ruling out heart failure, a disorder linked with volume overload of the ventricles, and is used for diagnosis, prognosis, and risk stratification. Pregnancy causes in healthy women changes in physical and hemodynamic parameters and appears to be a risk factor for severe COVID-19 illness. The purpose of this study is to highlight the significance of monitoring NT-proBNP levels during pregnancy, particularly in patients who were infected with COVID-19 during pregnancy or were infected with the virus while giving birth. The findings of this comparative research indicate the importance of NT-proBNP in terms of foetal prognosis and birthweight.

METHODS

We collected blood samples to measure NT-proBNP concentrations from a cohort of 186 pregnant patients divided into two groups based on the presence of SARS-CoV-2 viral infection.

RESULTS

Elevated NT-proBNP had an unfavourable implication on the newborn birth weight and Apgar score and expressed its influence on lower values.

CONCLUSIONS

We consider that NT-proBNP testing in pregnant patients, especially those with COVID-19 infection, can be relevant and be used as a predictive marker to be taken into consideration when it comes to management, outcome, and treatment regarding pregnant patients and their newborns.

Pregnancy-specific Reference Intervals for BNP and NT-pro BNP-Changes in Natriuretic Peptides Related to Pregnancy

Context

Cardiac disease is the leading cause of maternal mortality in the UK, so accurate cardiovascular diagnoses in pregnancy are essential. BNP (B-type natriuretic peptide) and NT-pro BNP (N-terminal-pro BNP) are useful clinical tools for investigating suspected peripartum cardiomyopathy but, as the pregnancy-specific reference intervals are undefined, it is uncertain how they should be interpreted in pregnant women.

Objectives

To define trimester-specific 95% reference intervals for BNP and NT-pro BNP in pregnancy.

Methods

Longitudinal study of 260 healthy pregnant women, with sampling in each trimester.

Results

The upper reference limit for NT-pro BNP was 200 pg/mL in the first and second trimesters, and 150 pg/mL in the third. Levels were significantly reduced in overweight women in the third trimester (P = .0001), which supports the partitioning of reference intervals by body mass index (BMI). The upper limit for BNP was 50 pg/mL, with no detectable trimester-related differences. Although other biomarkers (hemoglobin and platelets) fell throughout pregnancy, both natriuretic peptides were initially elevated before falling by the third trimester, suggesting that the observed changes in natriuretic peptides are driven by dynamic interplay between cardiac strain and progressive hemodilution. NT-pro BNP in the first trimester was inversely associated with neonatal birthweight at term (P = .011).

Conclusion

Cardiac biomarkers have an important role for investigating suspected disease in high-risk pregnant women, but a robust assessment of the levels expected in healthy pregnant women is an essential prerequisite to their application in clinical practice. This study has defined trimester- and BMI-specific reference intervals for NT-pro BNP and BNP, which may improve how women with suspected cardiovascular disease are investigated in pregnancy.

NT-proBNP: When is it useful in Obstetric Medicine?

Pregnancy, viewed as a stress test of the haemodynamic system, may unmask underlying cardiac disease. Pregnancy may also induce de novo cardiac disease. N-terminal pro brain-type natriuretic peptide (NT-proBNP) is a useful biomarker in all clinical conditions in which the ventricle is stressed and especially stretched in the general population. In hypertensive diseases of pregnancy, increased levels of NT-proBNP in preeclampsia are associated with increased cardiac filling pressures and diastolic dysfunction. Increased levels of NT-proBNP in pregnant women with known cardiac disease may lead to earlier diagnosis of impending heart failure. Similarly, elevated levels of NT-proBNP assist with the diagnosis of peripartum cardiomyopathy and are increasingly used in follow-up. Women with known congenital heart disease who are pregnant can be screened for risk of cardiac events such as heart failure by the use of NT-proBNP levels. There is a paucity of data in pregnancy with the use of NT-proBNP and more research is needed.

PLASMA CONCENTRATIONS AND CORRELATIONS OF NATRIURETIC PEPTIDES AND OXYTOCIN DURING LABOR AND EARLY POSTPARTUM PERIOD

Context

Natriuretic peptides (NP) and oxytocin (OT) play an important role in cardiovascular and hydro-electrolytic homeostasis. Changes in NP levels and their roles in cardiovascular adaptations in pregnancy and labor have not been clear.

Objective

The present study aimed to investigate the changes and correlations in plasma levels of atrial natriuretic peptide (ANP), C-type natriuretic peptide (CNP), B-type natriuretic peptide (BNP) and OT during labor and the postpartum period.

Study design

Blood samples were collected from 29 healthy pregnant women in the active phase of spontaneous labor, 15 minutes after delivery and 3 hours postpartum. Plasma levels of OT and the stable N-terminal fragments of NPs (NT-proANP, NT-proCNP, NT-proBNP) were measured using enzyme or electrochemiluminescence immunoassays.

Results

The plasma levels of NT-proANP and NT-proCNP significantly decrease 3 hours postpartum compared to the active phase of labor and to 15 minutes after delivery. The plasma NT-proBNP levels significantly higher after delivery and 3 hours postpartum compared to the active phase of labor. A significant correlation exists between OT and NT-proANP levels during the active phase of labor and 15 minutes after delivery.

Conclusions

The data show that during labor and postpartum, the plasma concentrations of the NPs change differently. Elevations in NT- proBNP after delivery suggest that BNP may be involved in postpartum adaptations. The correlations between OT and ANP levels indicate that OT may be partly responsible for the increased levels of ANP and may have a role in the modification of the cardiovascular system.

Cardiovascular biomarkers in paired maternal and umbilical cord blood samples at term and near term delivery

BACKGROUND

Cardiovascular biomarkers might help to identify fetuses or pregnancies at risk.

AIM

To examine the umbilical cord neonatal and maternal levels of cardiovascular biomarkers at the time of delivery, and to correlate maternal and fetal biomarker levels to each other, to gestational age and to delivery mode.

STUDY DESIGN

In a prospective, observational, cross-sectional, single-center study biomarkers were measured in paired maternal and umbilical venous cord blood samples.

SUBJECTS

The sample cohort included 66 sets of fetal and maternal blood samples (11 after multiple gestation, 53 after cesarean section, 17 after exposure to labor).

OUTCOME MEASURES

Midregional pro-adrenomedullin (MRproADM), midregional-pro atrial natriuretic peptide (MRproANP), brain natriuretic peptide (BNP), n-terminal-pro brain natriuretic peptide (NTproBNP), copeptin, and high sensitive troponin I (hsTnI) levels were measured.

RESULTS

Mean ± SEM for biomarker levels in umbilical venous/maternal blood were: MRproADM [nmol/L] 1.02 ± 0.04/1.24 ± 0.08, MRproANP [pmol/L] 215.53 ± 12.96/54.65 ± 3.41, BNP [pg/mL] 32.02 ± 3.37/19.76 ± 3.29, NTproBNP [pg/mL] 1228.94 ± 91.73/71.48 ± 8.65, copeptin [pmol/L] 103.42 ± 22.89/10.41 ± 1.71, and hsTnI [pg/mL] 13.54 ± 5.17/4.91 ± 2.37. Fetal MRproANP, NTproBNP, and BNP were inversely correlated with gestational age. Maternal and fetal MRproANP (r=0.472, p=0.002) and copeptin (r=0.572, p<0.001) levels were correlated, whereas there was no feto-maternal correlation for the other biomarkers. Fetal copeptin was elevated after exposure to labor.

CONCLUSIONS

Biomarker levels appear to be regulated independently in mother and fetus. Fetal biomarkers are influenced by gestational age and delivery mode. In this study on term and near term pregnancies without specific fetal pathology, correlation between paired maternal and fetal biomarker levels was weak or not demonstrable.

Low baseline proBNP associated with increased risk of intraoperative hypotension during spinal anaesthesia for cesarean delivery

BACKGROUND AND OBJECTIVES

Brain natriuretic peptide (BNP) has a role in the regulation of body fluid volume and blood pressure (BP). BNP remains within a normal range during spinal anaesthesia (SA) in patients undergoing cesarean delivery. However, the effect of BNP on changes in BP during the perioperative period has not been evaluated. We aimed to investigate the effect of preoperative serum BNP on the risk of hypotension during cesarean delivery with SA.

DESIGN AND SETTINGS

Patients were randomly selected among the patient group who were attending routine clinic visits for pregnancy monitoring. All had a healthy pregnancy and no other acute or chronic disease by their obstetrician. The study design was cross-sectional.

PATIENTS AND METHODS

Patients who had uncomplicated pregnancy process and no known medical dis.ease were selected consecutively during their last outpatient clinical examination. Baseline BP was recorded before SA. Simultaneously, blood samples were drawn for routine biochemistry and BNP. BP, SaO2, and electrocardiography were monitored during surgery. Intraoperative hypotension (IOH) was defined as >=25% decrease in mean arterial pressure (MAP) at the 5th minute of SA.

RESULTS

In 41 term pregnant women, 18 of the 41 patients (43.9%) fulfilled the criteria for IOH, while 23 (56.1%) showed a decrease 13.1 (11.3%) and were classified as normotensive. Baseline BNP was significantly lower in patients with IOH compared with normotensive patients 45.7 (26.9) vs.70.2 (40.5); P=.05. Baseline BNP had no significant correlation MAP at any time point. Age, body mass index, hemoglobin, baseline MAP and heart rate were not different between patients with and without IOH.

CONCLUSION

Those findings suggest that higher baseline BNP levels might have a protective role in development of hypotension in healthy term pregnant women during SA for cesarean delivery.

Amniotic fluid embolism pathophysiology suggests the new diagnostic armamentarium: β-tryptase and complement fractions C3-C4 are the indispensable working tools

Amniotic fluid embolism (AFE) is an uncommon obstetric condition involving pregnant women during labor or in the initial stages after delivery. Its incidence is estimated to be around 5.5 cases per 100,000 deliveries. Therefore, this paper investigated the pathophysiological mechanism, which underlies AFE, in order to evaluate the role of immune response in the development of this still enigmatic clinical entity. The following databases (from 1956 to September 2014) Medline, Cochrane Central, Scopus, Web of Science and Science Direct were used, searching the following key words: AFE, pathophysiology, immune/inflammatory response, complement and anaphylaxis. The main key word “AFE” was searched singularly and associated individually to each of the other keywords. Of the 146 sources found, only 19 were considered appropriate for the purpose of this paper. The clinical course is characterized by a rapid onset of symptoms, which include: acute hypotension and/or cardiac arrest, acute hypoxia (with dyspnoea, cyanosis and/or respiratory arrest), coagulopathies (disseminated intravascular coagulation and/or severe hemorrhage), coma and seizures. The pathology still determines a significant morbidity and mortality and potential permanent neurological sequelae for surviving patients. At this moment, numerous aspects involving the pathophysiology and clinical development are still not understood and several hypotheses have been formulated, in particular the possible role of anaphylaxis and complement. Moreover, the detection of serum tryptase and complement components and the evaluation of fetal antigens can explain several aspects of immune response.

Effects of caesarean section on serum levels of NT-proBNP

OBJECTIVE

To determine the effects of delivery by caesarean on serum levels of N-terminal fragment of precursor protein brain-type natriuretic peptide (NT-proBNP).

METHODS

Serum NT-proBNP levels were determined longitudinally at 24 and 36 weeks of gestation (GW) and on post-partum day 3 and month 1 (PPD3 and PPM1, respectively) in 78 women with normotensive singleton pregnancies. Thirty-nine women underwent caesarean delivery. Plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were determined on PPD3. Effects of maternal demographic characteristics on NT-proBNP levels were also analysed.

RESULTS

NT-proBNP levels (pg/ml) either in pregnancy or on PPM1 did not differ between women with vaginal and caesarean deliveries (44 ± 24 vs 41 ± 30, 24 GW; 37 ± 22 vs 29 ± 22, 36 GW; 43 ± 28 vs 39 ± 24, PPM1, respectively). Levels on PPD3 were significantly higher (94 ± 105 vs 247 ± 186, P < 0.0001) in women with caesarean delivery. Among women with caesarean delivery, a larger rise of NT-proBNP on PPD3 occurred in nulliparous than in multiparous women (319 ± 232 vs 185 ± 107, P = 0.023), while no rise occurred among multiparous women with vaginal delivery (108 ± 115 vs 47 ± 27). NT-proBNP levels on PPD3 were significantly and negatively correlated with PRA, PAC and maternal weight loss after childbirth on PPD3. These 3 variables on PPD3 were significantly lower in women undergoing caesarean than vaginal delivery (0.8 ± 0.4 vs 1.9 ± 1.4 ng/ml/h for PRA; 70 ± 38 vs 136 ± 88 pg/ml for PAC; 2.7 ± 1.2 vs 4.3 ± 1.1 kg for weight loss, each P < 0.0001).

CONCLUSIONS

The transient post-partum rise in serum NT-proBNP may reflect transient volume overload after parturition and is remarkable in nulliparous women, especially after caesarean section.

Serum 25-hydroxyvitamin D is not related to cardiac natriuretic peptide in nulliparous and lactating women

BACKGROUND

Vitamin D deficiency is associated with heightened risk of cardiovascular disease. Potential mechanisms include involvement of vitamin D in regulation of renin-angiotensin system and manufacture and secretion of cardiac natriuretic peptides. Our aim was to document relationships between 25 hydroxyvitamin [25(OH)D] and N-terminal pro B-type natriuretic peptide (NT-proBNP) and plasma renin activity (PRA) levels and to document the effect of vitamin D administration on NT-proBNP and PRA levels in vitamin D deficient subjects.

METHODS

Serum 25(OH)D, parathyroid hormone (PTH), plasma or serum NT-proBNP and PRA levels were measured at baseline in nulliparous and lactating women and after 2 months of oral vitamin D2 (2,000 IU/day or 60,000 IU/month) supplementation to lactating women.

RESULTS

Baseline levels of 25(OH)D were low (<50 nmol/L) in most women whereas PRA and NT-proBNP levels were within the normal range. There were no significant correlations between baseline 25(OH)D or PTH with NT-proBNP and PRA. Vitamin D administration over a 2-month period in lactating women was associated with a decline in NT-proBNP (by 9.1 +/- 2.0 pmol/L; p < 0.001) and PRA (by 0.32 +/- 0.17 nmol/L/hr; p = 0.064). However, there were no significant correlations between the changes from baseline in 25(OH)D and either NT-proBNP (r = -0.04, p = 0.8) or PRA (r = -0.04, p = 0.8).

CONCLUSION

We found no significant correlations between 25(OH)D or PTH with NT-proBNP and PRA in vitamin D deficient women. Further information is required to clarify the effects of vitamin D administration on cardiac structure and function.

Perinatal changes of circulating N-terminal pro B-type natriuretic peptide (NT-proBNP) in normal and intrauterine-growth-restricted pregnancies

OBJECTIVE

To investigate changes in NT-proBNP in intrauterine-growth-restricted (IUGR) and appropriate-for-gestational-age (AGA) pregnancies.

METHODS

NT-proBNP levels were measured in 40 mothers (MS), umbilical cords (UC), and their 20 IUGR/ 20 AGA neonates on day 1 (N1) and day 4 (N4).

RESULTS

UC, N1, and N4 NT-proBNP was lower in IUGR pregnancies (p <or= 0.049). In both groups, NT-proBNP levels were similar in MS and higher in N1 (p <or= 0.001). In AGA, MS NT-proBNP correlated positively with UC.

CONCLUSIONS

Fetal and neonatal NT-proBNP levels are lower in IUGR compared with AGA, probably due to blood flow redistribution in IUGR and NT-proBNP placental transport in AGA. NT-proBNP levels peak on N1.