Effect of lactation on maternal postpartum cardiac function and adiposity: a murine model

The relationship between pregnancy count and duration of breast-feeding with metabolic syndrome (Fasa Persian cohort study)

BACKGROUND

Changes that occur during pregnancy and after that during breastfeeding induce some symptoms similar to metabolic syndrome (MetS) risk factors. This study aims to determine the relationship between pregnancy, as well as the duration of breastfeeding and MetS controlling the effect of other risk factors like hypertension, glucose intolerance, triglyceride, central obesity, and reduction of high-density lipoprotein in women of Fasa Persian Cohort Study.

MATERIALS AND METHODS

In this cross-sectional study, 5015 women aged 35-70 years were investigated in the Sheshdeh region from 2016 to 2021, and the information related to the disease symptoms was collected through questionnaires, examinations, and laboratory tests. MetS was calculated based on two guidelines according to adult treatment panel III (ATP III) and international diabetes federation (IDF) methods. For reporting the data, the odds ratio with its 95% confidence interval was used. In order to eliminate the effect of confounders, logistic regression was used.

RESULTS

Prevalence of MetS showed a descending trend in women with up to two pregnancies and it reached 22.6% and 22.4% using ATPIII and IDF methods respectively, while with an increase in the number of pregnancies of more than two, MetS prevalence was ascending. The prevalence of MetS did not have any specific trend across various breastfeeding duration groups. Multivariate analysis approved that the odds ratio of developing MetS in comparison with women who had two pregnancies was significantly increasing trend when the pregnancy counts increased.

CONCLUSION

The chance of developing MetS based on both IDF and ATP III methods after adjustment for confounding effects would grow with an increase in the number of pregnancies to more than two and breast-feeding of more than seven years. It is recommended that women with more than two pregnancies or the long duration of breast-feeding women undergo a specialized examination to investigate and control MetS problems so that future diseases could be prevented.

The adaptation of maternal energy metabolism to lactation and its underlying mechanisms

Maternal energy metabolism undergoes a singular adaptation during lactation that allows for the caloric enrichment of milk. Changes in the mammary gland, changes in the white adipose tissue, brown adipose tissue, liver, skeletal muscles and endocrine pancreas are pivotal for this adaptation. The present review details the landmark studies describing the enzymatic modulation and the endocrine signals behind these metabolic changes. We will also update this perspective with data from recent studies showing transcriptional and post-transcriptional mechanisms that mediate the adaptation of the maternal metabolism to lactation. The present text will also bring experimental and observational data that describe the long-term consequences that short periods of lactation impose to maternal metabolism.

Obesity, not a high fat, high sucrose diet alone, induced glucose intolerance and cardiac dysfunction during pregnancy and postpartum

Cardiovascular disease is the leading cause of death in women during pregnancy and the postpartum period. Obesity is an independent risk factor for cardiovascular diseases. Nearly 60% of women of reproductive age are considered overweight or obese, cardiovascular disease morbidity and mortality continue to be pervasive. The objective of this study was to determine the effects of an obesogenic diet on the cardiometabolic health of dams during pregnancy and postpartum. Female mice were fed either a high-fat, high-sucrose diet (HFHS) or a refined control diet (CON) for 8 weeks before initiation of pregnancy and throughout the study period. Mice in the HFHS showed two distinct phenotypes, obesity-prone (HFHS/OP) and obesity resistance (HFHS/OR). Pre-pregnancy obesity (HFHS/OP) induced glucose intolerance before pregnancy and during postpartum. Systolic function indicated by the percent fractional shortening (%FS) was significantly decreased in the HFHS/OP at late pregnancy (vs. HFHS/OR) and weaning (vs. CON), but no differences were found at 6 weeks of postpartum among groups. No induction of pathological cardiac hypertrophy markers was found during postpartum. Plasma adiponectin was decreased while total cholesterol was increased in the HFHS/OP. Our results suggested that obesity, not the diet alone, negatively affected cardiac adaptation during pregnancy and postpartum.

l-Citrulline supplementation during pregnancy improves perinatal and postpartum maternal vascular function in a mouse model of preeclampsia

Preeclampsia is a spontaneously occurring pregnancy complication diagnosed by new-onset hypertension and end-organ dysfunction with or without proteinuria. This pregnancy-specific syndrome contributes to maternal morbidity and mortality and can have detrimental effects on fetal outcomes. Preeclampsia is also linked to increased risk of maternal cardiovascular disease throughout life. Despite intense investigation of this disorder, few treatment options are available. The aim of this study was to investigate the potential therapeutic effects of maternal l-citrulline supplementation on pregnancy-specific vascular dysfunction in the male C57BL/6J × female C57BL/6J C1q-/- preeclampsia-like mouse model. l-Citrulline is a nonessential amino acid that is converted to l-arginine to promote smooth muscle and blood vessel relaxation and improve nitric oxide (NO)-mediated vascular function. To model a preeclampsia-like pregnancy, female C57BL/6J mice were mated to C1q-/- male mice, and a subset of dams was supplemented with l-citrulline throughout pregnancy. Blood pressure, systemic vascular glycocalyx, and ex vivo vascular function were investigated in late pregnancy, and postpartum at 6 and 10 mo of age. Main findings show that l-citrulline reduced blood pressure, increased vascular glycocalyx volume, and rescued ex-vivo vascular function at gestation day 17.5 in this preeclampsia-like model. The vascular benefit of l-citrulline also extended postpartum, with improved vascular function and glycocalyx measures at 6 and 10 mo of age. l-Citrulline-mediated vascular improvements appear, in part, attributable to NO pathway signaling. Taken together, l-citrulline supplementation during pregnancy appears to have beneficial effects on maternal vascular health, which may have translational implications for improved maternal cardiovascular health.

Association between breastfeeding and preeclampsia in parous women: a case -control study

Background

Preeclampsia is a global health problem and it is the main cause of maternal and perinatal morbidity and mortality. Breastfeeding has been reported to be associated with lower postpartum blood pressure in women with gestational hypertension. However, there is no published data on the role that breastfeeding might play in preventing preeclampsia. The aim of the current study was to investigate if breastfeeding was associated with preeclampsia in parous women.

Method

A case-control study was conducted in Saad Abualila Maternity Hospital in Khartoum, Sudan, from May to December 2019. The cases (n = 116) were parous women with preeclampsia. Two consecutive healthy pregnant women served as controls for each case (n = 232). The sociodemographic, medical, and obstetric histories were gathered using a questionnaire. Breastfeeding practices and duration were assessed.

Results

A total of 98 (84.5%) women with preeclampsia and 216 (93.1%) women in the control group had breastfed their previous children. The unadjusted odds ratio (OR) of preeclampsia (no breastfeeding vs breastfeeding) was 3.55, 95% confidence interval (CI) 1.64,7.70 and p value = 0.001 based on these numbers. After adjusting for age, parity, education level, occupation, history of preeclampsia, history of miscarriage, body mass index groups the adjusted OR was 3.19, 95% CI 1.49, 6.82 (p value = 0.006).

Conclusion

Breastfeeding might reduce the risk for preeclampsia. Further larger studies are required.

Reference values for 2-dimensional and M-mode echocardiography in Friesian and Warmblood horses

BACKGROUND

Echocardiographic reference intervals for Friesian horses are poorly described.

OBJECTIVES

To obtain reference intervals for echocardiographic measurements in Friesians and compare these with Warmbloods.

ANIMALS

One hundred healthy adult Friesians and 100 healthy adult Warmblood horses.

METHODS

Cross-sectional study. Two-dimensional and M-mode echocardiographic images were obtained. Echocardiographic measurements, including size, area, and volumetric measurements of left atrium, left and right ventricle, aorta, and pulmonary artery, were performed. Measurements were compared between the 2 breeds using an independent samples t test with Bonferroni correction for multiple comparisons.

RESULTS

Reference ranges for standard echocardiographic measurements in Friesians were obtained. Several left ventricular measurements were significantly smaller in Friesians compared to Warmbloods, such as the left ventricular end-diastolic volume using the 4-chamber modified Simpsons' method (99.85% confidence interval for the difference [CI] = -245 to -63). Also the right ventricular end-diastolic and peak-systolic internal diameter were smaller in Friesians (99.85% CI = -1.33 to -0.6 and 99.85% CI = -1.54 to -0.76, respectively). Fractional shortening (99.85% CI = 0.61-6) and ejection fraction (99.85% CI = 0.21-4.6) were significantly larger. No structural effects of systemic hypertension, such as concentric hypertrophy, were detected.

CONCLUSIONS AND CLINICAL IMPORTANCE

Our study provides reference intervals for echocardiographic measurements in Friesians useful in a clinical setting. In general, the left ventricular dimensions in Friesians were significantly smaller compared to Warmbloods, emphasizing the need for breed-specific reference intervals.

Paternal deficiency of complement component C1q leads to a preeclampsia-like pregnancy in wild-type female mice and vascular adaptations postpartum

Preeclampsia is a spontaneously occurring, pregnancy-specific syndrome that is clinically diagnosed by new onset hypertension and proteinuria. Epidemiological evidence describes an association between a history of preeclampsia and increased risk for cardiovascular disease in later life; however, the mechanism(s) driving this relationship are unclear. Our study aims to leverage a novel preeclampsia-like mouse model, the C1q^-/- model, to help elucidate the acute and persistent vascular changes during and following a preeclampsia-like pregnancy. Female C57BL/6J mice were mated to C1q^-/- male mice to model a preeclampsia-like pregnancy ("PE-like"), and the maternal cardiovascular phenotype (blood pressure, renal function, systemic glycocalyx, and ex vivo vascular function) was assessed in late pregnancy and postpartum at 6 and 10 mo of age. Uncomplicated, normotensive pregnancies (female C57BL/6J bred to male C57BL/6J mice) served as age-matched controls. In pregnancy, PE-like dams exhibited increased systolic and diastolic pressure during mid- and late gestation, renal dysfunction, fetal growth restriction, and reduced placental efficiency. Ex vivo wire myography studies of mesenteric arteries revealed severe pregnancy-specific endothelial-dependent and -independent vascular dysfunction. At 3 and 7 mo postpartum (6 and 10 mo old, respectively), hypertension resolved in PE-like dams, whereas mild vascular dysfunction persisted at 3 mo postpartum. In conclusion, the female C57BL/6J-by-male C57BL/6J C1q^-/- model recapitulates many aspects of the human preeclampsia syndrome in a low-risk, wild-type female mouse. The pregnancy-specific phenotype results in systemic maternal endothelial-dependent and -independent vascular dysfunction that persists postpartum.

Lactation Leads to Modifications in Maternal Renin-Angiotensin System in Later Life

The objective of this study was to evaluate whether the renin-angiotensin system (RAS) is associated with maternal cardioprotective phenotype observed in post-lactated mice later in life. Following the delivery, CD-1 female mice were randomized to one of the following groups: lactated (nursed pups for 3 weeks, n = 10) or non-lactated (pups were removed after birth, n = 10). The mice were sacrificed 6 months after the delivery, and tissues were collected. Protein levels of angiotensinogen, angiotensin type 1 and 2 receptors (AT1R, AT2R), angiotensin converting enzymes (ACE, ACE2), and MAS receptor were determined using Western blot. Results were analyzed using Student's t-test and Mann-Whitney test as appropriate (significance: P < 0.05). Angiotensinogen levels were significantly lower in the liver (P = 0.0002), and ACE was significantly decreased in the lungs (P = 0.04) and kidney (P = 0.001) from lactated mice as compared to non-lactated. The levels of AT2R in the kidney (P = 0.02) and visceral adipose tissue (VAT, P = 0.04), the ACE 2 in the VAT (P = 0.03) and heart (P = 0.04), and MAS receptor in VAT (P = 0.02) were significantly elevated in tissues from lactated mice. No other differences were found. Lactation led to the upregulation and downregulation of selected RAS components in lactated mice as compared to non-lactated group and may be a contributing factor to maternal cardioprotective phenotype later in life. Further studies are needed to dissect the mechanisms between lactation and the long-term maternal cardiometabolic benefits, which could lead to the therapies to prevent cardiovascular disease in women.

Long-Term Effect of Lactation on Maternal Cardiovascular Function and Adiposity in a Murine Model

OBJECTIVE

Epidemiological studies suggest that lactation is associated with long-term maternal health benefits. To avoid confounders in human studies, we used a previously characterized murine model to investigate the long-term effect of lactation on both cardiovascular function and adiposity.

STUDY DESIGN

After the delivery of the pups, CD-1 female mice were randomly divided into two groups: lactated and nonlactated (NL). Before pregnancy and at 9 months postdelivery, blood pressure was measured using a tail cuff, visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were assessed by computed tomography (CT), echocardiography was performed using microultrasound, and cholesterol panels and fasting blood glucose were measured. The data were analyzed using Student's t-test (significance at p < 0.05).

RESULTS

There were no differences in baseline parameters between the two groups. At 9 months postdelivery, the NL group weighed significantly more (p = 0.03) and demonstrated a significantly lower cardiac output (p = 0.05) and ejection fraction (p = 0.03). The mice in the NL group also had higher VAT (p < 0.01) and SAT percentiles (p = 0.03). Fasting glucose (p = 0.01) and low-density lipoprotein (p = 0.01) were significantly higher in the NL group at 9 months.

CONCLUSION

Our results show the benefit of lactation is not just limited to the immediate postpartum period but it also extends into midlife in a murine model.

Relationship of Postpartum Levels of Cystatin and High-Sensitivity C-Reactive Protein and Duration of Lactation in Mothers with Previous Gestational Hypertension or Preeclampsia

Background: Women with hypertensive disorders of pregnancy are at increased risk of cardiovascular disease in later life. We sought to determine the association between lactation and markers of maternal cardiovascular health among postpartum women with and without hypertensive disorders of pregnancy via measures of inflammation (high-sensitivity C-reactive protein [hsCRP]) and renal function (cystatin C). Materials and Methods: This prospective cohort study enrolled primarily overweight and obese women during early pregnancy. At a postpartum study visit occurring 6-24 months after delivery, we collected data on lactation duration and measured hsCRP and cystatin C. We assessed associations between lactation duration and levels of hsCRP and cystatin C among normotensive women and women with preeclampsia or gestational hypertension using analysis of variance and chi-squared tests. Linear regression models adjusted for age, race, education, prepregnancy body mass index, current smoking, and time since delivery. Results: Of 425 women, 37 (9%) had preeclampsia and 48 (11%) had gestational hypertension during enrollment pregnancy. The postpartum visit occurred at a mean of 8.6 ± 4.4 months after delivery. Women with a history of preeclampsia had significantly higher levels of cystatin C (mean 0.86 versus 0.78 mg/L; p = 0.03) compared with normotensive women, but nonsignificant elevation in hsCRP (mean 8.39 versus 6.04 mg/L; p = 0.08). Women with gestational hypertension had no differences in mean hsCRP or cystatin C compared with normotensive women. Among the 237 women with any lactation, 78 (18%) lactated for at least 6 months. Lactation duration both in the overall sample and among women with gestational hypertension or preeclampsia was not associated with levels of hsCRP or cystatin C. Conclusions: Preeclampsia history was associated with elevated postpartum levels of cystatin C; however, duration of lactation was not associated with postpartum hsCRP or cystatin C, regardless of history of gestational hypertension or preeclampsia. Further research is needed on mechanisms through which lactation may affect maternal risk of cardiovascular disease.

Effect of Lactation on Maternal Hypertension: A Systematic Review

INTRODUCTION

Hypertension is relatively common in pregnancy, and pregnancy may unmask hypertension among women who are predisposed to it. Lactation may be a means through which to mitigate pregnancy-related vascular risk. The impact of lactation on maternal blood pressure, and the duration of any effect, remains unclear. This study aimed at systematically reviewing the literature evaluating the impact of lactation on the development of hypertension.

MATERIALS AND METHODS

We searched PubMed, including EMBASE and MEDLINE, for studies that reported on the association between breastfeeding and maternal risk of hypertension that were published in a peer-reviewed source. The quality of the studies included was assessed by using the Newcastle-Ottawa Scale.

RESULTS

Nineteen studies met all inclusion criteria for this review. Of the four studies with short-term follow-up, 50% showed a protective association. The fifteen studies with longer-term follow-up were stratified by outcome assessed. Sixty-seven percent of the studies that evaluated for elevated blood pressure and 100% of the studies evaluating for an outcome of hypertension showed a protective association. The minimum duration of lactation associated with a benefit was 1 month. This association was demonstrated in follow-up periods as long as two to three decades. Studies that showed a protective association had overall higher quality ratings.

DISCUSSION

Lactation is associated with a beneficial effect on maternal blood pressure that persists for decades. These results add to the growing body of literature demonstrating the protective association of lactation on maternal cardiovascular risk. Providers may incorporate the decreased risk of hypertension into their counseling on the maternal benefits of lactation.

Pregnancy-Induced Physiologic Adaptation of the Abdominal Aorta Is Associated with Changes in Gene Expression and Genomic Methylation

BACKGROUND/AIMS

Ten-eleven translocation 2 (Tet2), a DNA demethylase enzyme, has been identified as a master epigenetic regulator of vascular smooth muscle cell plasticity. We hypothesized that pregnancy will induce significant adaptive changes in aortic biomechanics that correlate with the Tet family gene expression.

METHODS

Abdominal aortas from pregnant and nonpregnant mice were dissected and cannulated. Intraluminal pressure was adjusted using a pressure-servo system while using a video dimension analyzer to measure the lumen diameter. Quantitative polymerase chain reaction and immunoblot was used to analyze the expression of Tet genes. Global genomic methylation was assessed with the luminometric methylation assay.

RESULTS

Compared to the nonpregnant (NP, 706 ± 8 µm) control group, the aortic luminal diameter was significantly increased in both E18.5 (836 ± 14 µm) and PP30 (889 ± 16 µm) mice. Distensibility was reduced in E18.5 (90 ± 4%) mice and returned to NP values (108 ± 2%) in PP30 (108 ± 3%) mice. Tet2 transcription decreased at the beginning of pregnancy and subsequently increased in late gestation, inversely corresponding to changes in global methylation.

CONCLUSION

Physiologic changes in the aorta were accompanied by changes in gene expression and genomic methylation, suggesting an epigenetic component to maternal vascular remodeling during pregnancy.

Counseling About the Maternal Health Benefits of Breastfeeding and Mothers' Intentions to Breastfeed

Objectives To evaluate the impact of counseling regarding the maternal health effects of lactation on pregnant women's intentions to breastfeed. Methods Women seeking prenatal care at an urban university hospital completed surveys before and after receiving a 5-min counseling intervention regarding the maternal health effects of breastfeeding. The counseling was delivered by student volunteers using a script and one-page infographic. Participants were asked the likelihood that breastfeeding affects maternal risk of multiple chronic conditions using 7-point Likert scales. We compared pre/post changes in individual item responses and a summary score of knowledge of the maternal health benefits of lactation (MHBL) using paired t tests. Multivariable logistic regression was used to examine the impact of increases in knowledge of MHBL on participants' intentions to breastfeed. Results The average age of the 65 participants was 24 ± 6 years. Most (72 %) were African-American and few (9 %) had college degrees. Half (50 %) had previously given birth, but few (21 %) had previously breastfed. Before counseling, few were aware of any benefits of lactation for maternal health. After counseling, knowledge of MHBL increased (mean knowledge score improved from 19/35 to 26/35, p < 0.001). Improvement in MHBL knowledge score was associated with increased intention to try breastfeeding (aOR 1.20, 95 % CI 1.02-1.42), of wanting to breastfeed (aOR 1.45, 95 % CI 1.13-1.86), and feeling that breastfeeding is important (aOR 1.21, 95 % CI 1.03-1.42). Conclusions for Practice Brief structured counseling regarding the effects of lactation on maternal health can increase awareness of the maternal health benefits of breastfeeding and strengthen pregnant women's intentions to breastfeed.

Effect of Normal Pregnancy Followed by Lactation on Long-Term Maternal Health in a Mouse Model

Although it has been widely accepted that pregnancies with complications are associated with increased maternal cardiovascular risk later in life, there is no consensus if noncomplicated pregnancy followed by lactation plays a protective role or is a risk factor. The objective of this study was to investigate the effects of normal pregnancy and lactation on long-term maternal health in a mouse model. CD-1 mice were allocated to breeding (primigravid [PG]) and nonbreeding (nulligravid [NG]) groups. The PG group proceeded through normal pregnancy and delivery. Using a telemetry system, blood pressure (BP) was analyzed in the PG group at 6 months postpartum and in age-matched NG mice. Serum analytes, gene expressions, and protein levels were determined using appropriate analysis methods. Primigravid mice had significantly lower systolic and diastolic BP and fasting glucose levels. Circulating oxytocin (OXT) levels were significantly higher in PG mice. Oxt gene expression was significantly higher in the heart and aorta and lower in visceral adipose tissue (VAT) from PG mice. The oxytocin receptor ( Oxtr) gene expression was significantly higher in the heart, aorta, and VAT from PG animals. The level of Oxtr DNA hypermethylation and the expression of mmu-miR-29a were significantly lower in the hearts of PG mice. In PG VAT, glucose transporter-4 expression was significantly higher. Our study demonstrates that a history of normal pregnancy followed by lactation was associated with lower maternal cardiovascular risk factors later in life in female mouse.

Postnatal Cardiovascular Consequences in the Offspring of Pregnant Rats Exposed to Smoking and Smoking Cessation Pharmacotherapies

Approximately 20% of pregnant women smoke despite intentions to quit. Smoking cessation drugs, such as nicotine replacement therapy (NRT) and bupropion, are recommended treatments. Adverse cardiovascular outcomes in offspring have raised concerns about NRT's safety during pregnancy. However, the effect of bupropion is unknown. Using a rat model, we determined whether NRT and bupropion interventions during pregnancy are safer than continued smoking on offspring's cardiovascular function. Male offspring of controls and dams exposed to cigarette smoke (1.6 packs/day, inhalation), nicotine (2 mg/kg/d subcutaneously), and bupropion (13 mg/kg twice daily orally) were assessed for fetoplacental weight, cardiac function, blood pressure, and vascular reactivity. Fetoplacental weights were decreased and spontaneous beating and intracellular calcium in neonatal cardiomyocytes were increased in smoking, nicotine, and bupropion offspring; however, these effects were more accentuated in smoking followed by nicotine and bupropion offspring. Increased heart rate and decreased cardiac output, stroke volume, and left ventricular percent posterior wall thickening were observed in smoking, nicotine, and bupropion offspring. The left ventricular mass was reduced in smoking and nicotine but not in bupropion offspring. Blood pressure was higher with decreased endothelium-dependent relaxation and exaggerated vascular contraction to angiotensin II in smoking and nicotine offspring, with more pronounced dysfunctions in smoking than nicotine offspring. Maternal bupropion did not impact offspring's blood pressure, endothelium-dependent relaxation, and vascular contraction. In conclusion, maternal nicotine intervention adversely affects offspring's cardiovascular outcomes, albeit less severely than continued smoking. However, bupropion causes cardiac derangement in offspring but does not adversely affect blood pressure and vascular function.

Characterization of visceral and subcutaneous adipose tissue transcriptome in pregnant women with and without spontaneous labor at term: implication of alternative splicing in the metabolic adaptations of adipose tissue to parturition

OBJECTIVE

The aim of this study was to determine gene expression and splicing changes associated with parturition and regions (visceral vs. subcutaneous) of the adipose tissue of pregnant women.

STUDY DESIGN

The transcriptome of visceral and abdominal subcutaneous adipose tissue from pregnant women at term with (n=15) and without (n=25) spontaneous labor was profiled with the Affymetrix GeneChip Human Exon 1.0 ST array. Overall gene expression changes and the differential exon usage rate were compared between patient groups (unpaired analyses) and adipose tissue regions (paired analyses). Selected genes were tested by quantitative reverse transcription-polymerase chain reaction.

RESULTS

Four hundred and eighty-two genes were differentially expressed between visceral and subcutaneous fat of pregnant women with spontaneous labor at term (q-value <0.1; fold change >1.5). Biological processes enriched in this comparison included tissue and vasculature development as well as inflammatory and metabolic pathways. Differential splicing was found for 42 genes [q-value <0.1; differences in Finding Isoforms using Robust Multichip Analysis scores >2] between adipose tissue regions of women not in labor. Differential exon usage associated with parturition was found for three genes (LIMS1, HSPA5, and GSTK1) in subcutaneous tissues.

CONCLUSION

We show for the first time evidence of implication of mRNA splicing and processing machinery in the subcutaneous adipose tissue of women in labor compared to those without labor.

Effects of lactation on postpartum blood pressure among women with gestational hypertension and preeclampsia

BACKGROUND

Women with a history of hypertensive disorders of pregnancy are at an increased risk of hypertension and cardiovascular disease in later life. Lactation has been associated with a reduced risk of maternal hypertension, both in the postpartum period and later life. However, little is known about whether lactation is also cardioprotective in women with hypertensive disorders of pregnancy such as preeclampsia or gestational hypertension.

OBJECTIVE

This study aimed to characterize the relationship between lactation and postpartum blood pressure among women with preeclampsia and gestational hypertension.

STUDY DESIGN

Data were obtained from women who participated in the Prenatal Exposures and Preeclampsia Prevention study (n = 379; 66% African American; 85% overweight or obese). Women enrolled during pregnancy and attended a postpartum visit (on average, 9.1 months after delivery) during which data on lactation duration and blood pressure were collected. The significance of the associations between postpartum blood pressure and lactation among women who remained normotensive during pregnancy, developed gestational hypertension, or developed preeclampsia were assessed with an analysis of variance. Linear regression models were used to adjust for maternal age, race, education, prepregnancy weight, and time since delivery.

RESULTS

Gestational hypertension affected 42 subjects (11%) and preeclampsia affected 33 (9%). Lactation was reported by 217 (57%) with 78 (21%) reporting ≥ 6 months of lactation. Women who lactated were somewhat older, more educated, and had higher socioeconomic status. Among women who had gestational hypertension, lactation was associated with lower systolic blood pressure (P = .02) and diastolic blood pressure (P = .02). This association persisted after adjustment for age, race, education, prepregnancy weight, and time since delivery. However, for women who had preeclampsia and women who remained normotensive during pregnancy, lactation was not associated with postpartum blood pressure in either bivariate or multivariate analyses.

CONCLUSION

This study found that lactation is associated with lower postpartum blood pressure among overweight women who develop gestational hypertension but not among women who develop preeclampsia. Future studies are needed to explore the association of lactation and blood pressure in later life for women with hypertensive disorders of pregnancy.

Lactation Is a Risk Factor of Postpartum Heart Failure in Mice with Cardiomyocyte-specific Apelin Receptor (APJ) Overexpression

The G protein-coupled receptor APJ and its ligand apelin are highly expressed in cardiovascular tissues and are associated with the regulation of blood pressure and cardiac function. Although accumulating evidence suggests that APJ plays a crucial role in the heart, it remains unclear whether up-regulation of APJ affects cardiac function. Here we generated cardiomyocyte-specific APJ-overexpressing (APJ-TG) mice and investigated the cardiac phenotype in APJ-TG mice. Male and non-pregnant APJ-TG mice showed cardiac hypertrophy, contractile dysfunction, and elevation of B-type natriuretic peptide gene expression in the heart but not cardiac fibrosis and symptoms of heart failure, including breathing abnormality and pleural effusion. We further examined the influence of APJ overexpression in response to physiological stress induced by pregnancy and lactation in the heart. Interestingly, repeating pregnancy and lactation (pregnancy-lactation cycle) exacerbated cardiac hypertrophy and systolic dysfunction and induced cardiac fibrosis, lung congestion, pleural effusion, and abnormal breathing in APJ-TG mice. These data indicate that female APJ-TG mice develop postpartum cardiomyopathy. We showed that lactation, but not parturition, was critical for the onset of postpartum cardiomyopathy in APJ-TG mice. Furthermore, we found that lactating APJ-TG mice showed impaired myocardial angiogenesis and imbalance of pro- and antiangiogenic gene expression in the heart. These results demonstrate that overexpression of APJ in cardiomyocytes has adverse effects on cardiac function in male and non-pregnant mice and that lactation contributes to the development of postpartum cardiomyopathy in the heart with APJ overexpression.

Characterization of Visceral and Subcutaneous Adipose Tissue Transcriptome and Biological Pathways in Pregnant and Non-Pregnant Women: Evidence for Pregnancy-Related Regional-Specific Differences in Adipose Tissue

Objective

The purpose of this study was to compare the transcriptome of visceral and subcutaneous adipose tissues between pregnant and non-pregnant women.

Study Design

The transcriptome of paired visceral and abdominal subcutaneous adipose tissues from pregnant women at term and matched non-pregnant women (n = 11) was profiled with the Affymetrix Human Exon 1.0 ST array. Differential expression of selected genes was validated with the use of quantitative reverse transcription–polymerase chain reaction.

Results

Six hundred forty-four transcripts from 633 known genes were differentially expressed (false discovery rate (FDR) <0.1; fold-change >1.5), while 42 exons from 36 genes showed differential usage (difference in FIRMA scores >2 and FDR<0.1) between the visceral and subcutaneous fat of pregnant women. Fifty-six known genes were differentially expressed between pregnant and non-pregnant subcutaneous fat and three genes in the visceral fat. Enriched biological processes in the subcutaneous adipose tissue of pregnant women were mostly related to inflammation.

Conclusion

The transcriptome of visceral and subcutaneous fat depots reveals pregnancy-related gene expression and splicing differences in both visceral and subcutaneous adipose tissue. Furthermore, for the first time, alternative splicing in adipose tissue has been associated with regional differences and human parturition.

Associations Among Lactation, Maternal Carbohydrate Metabolism, and Cardiovascular Health

In mammalian reproductive physiology, lactation follows pregnancy; growing evidence suggests that disruption of this physiology affects a woman's lifetime risk of metabolic disease. These differences may reflect lactation-induced mobilization of fat stores and modulation of maternal stress reactivity. In addition, confounders may play a role: women who breastfeed for long durations are more likely to engage in other healthy behaviors, and obesity and insulin resistance may interfere with breastfeeding physiology. These findings underscore the importance of evidenced-based care to enable women to achieve their infant feeding goals.

Invited Commentary: Breastfeeding and Maternal Cardiovascular Health--Weighing the Evidence

Recently, there has been growing interest in understanding the ways in which lactation affects maternal health. The accompanying article by Palmer et al. (Am J Epidemiol. 2015;181(12):932-939), particularly their finding that prepregnancy obesity modifies the relationship between lactation and postpartum weight gain, makes an important contribution to this field. In this commentary, I discuss these findings within the context of other recent literature which indicates that whether or not a mother breastfeeds her newborn appears to be a powerful predictor of the mother's future risk of developing diabetes, hypertension, and cardiovascular disease, independent of maternal weight or body mass index in later life.

Does breastfeeding prevent the metabolic syndrome, or does the metabolic syndrome prevent breastfeeding?

In mammalian physiology, lactation follows pregnancy. Disruption of this physiology is associated with long-term adverse maternal health outcomes, including higher risks of later-life obesity, type 2 diabetes, metabolic syndrome, hypertension, and cardiovascular disease. Multiple mechanisms likely contribute to these associations, including the metabolic demands of breastfeeding, modulation of stress reactivity, and confounding by other health behaviors. At the same time, evidence suggests that maternal metabolic health entering pregnancy affects lactation performance. In this paradigm, adverse lactation outcomes may be a marker for underlying maternal disease risk. Understanding these relationships has important clinical and policy implications for women's health.