Maternal Obesity and Risk of Early-onset Neonatal Bacterial Sepsis: Nationwide Cohort and Sibling-controlled Studies

Grandmaternal body mass index in early pregnancy and risk of infant mortality in grandoffspring: a population-based multigeneration cohort study

BACKGROUND

Maternal obesity increases risk of infant mortality. Because obesity is highly inheritable, grandmaternal obesity could also play a role. However, it is unknown whether grandmaternal obesity is related to grandoffspring infant mortality risk.

OBJECTIVES

We investigated the associations of grandmaternal early pregnancy body mass index [BMI (in kg/m2)] and grandoffspring infant mortality risk.

METHODS

Using Swedish nationwide registers, we estimated infant mortality hazard ratios (HRs) by levels of maternal grandmaternal early pregnancy BMI among 315,461 singleton live-born grandoffspring. We examined whether the association was mediated through maternal body size. In a subset of 164,095 grandsoffspring we evaluated the role of paternal grandmaternal BMI. To explore whether factors shared within families explained these associations, we studied the relations of maternal or paternal full sisters' BMI and infant mortality.

RESULTS

Maternal grandmaternal overweight or obesity (BMI ≥ 25.0) was associated with increased grandoffspring infant mortality risk. Compared with the population median BMI (21.7), estimated adjusted hazard ratios [HRs (95% confidence interval [CI])] of grandoffspring mortality for BMI 25.0 and 30.0 were, respectively, 1.60 (1.14, 2.23) and 1.61 (1.13, 2.27). Maternal high birth weight-for-gestational age and early pregnancy obesity (BMI ≥ 30.0) were also associated with increased infant mortality risk. The association between maternal grandmaternal overweight or obesity and grandoffspring infant mortality was mostly (62%) mediated through maternal overweight or obesity. Maternal sisters' BMI was unrelated to infant mortality. Paternal grandmaternal obesity was associated with increased infant mortality risk (HR [95% CI] for BMI 30.0 compared with 21.7: 1.65 [1.02, 2.67]); associations with paternal sisters' BMI were not statistically significant.

CONCLUSIONS

Maternal grandmaternal overweight or obesity is associated with increased risk of grandoffspring infant mortality; factors shared within families may not play a major role. The association is mediated through the maternal early pregnancy BMI. Whether the association with paternal grandmaternal BMI is explained by shared familial factors warrants future confirmation.

Palmitate and group B Streptococcus synergistically and differentially induce IL-1β from human gestational membranes

Introduction

Rupture of the gestational membranes often precedes major pregnancy complications, including preterm labor and preterm birth. One major cause of inflammation in the gestational membranes, chorioamnionitis (CAM) is often a result of bacterial infection. The commensal bacterium Streptococcus agalactiae, or Group B Streptococcus (GBS) is a leading infectious cause of CAM. Obesity is on the rise worldwide and roughly 1 in 4 pregnancy complications is related to obesity, and individuals with obesity are also more likely to be colonized by GBS. The gestational membranes are comprised of several distinct cell layers which are, from outermost to innermost: maternally-derived decidual stromal cells (DSCs), fetal cytotrophoblasts (CTBs), fetal mesenchymal cells, and fetal amnion epithelial cells (AECs). In addition, the gestational membranes have several immune cell populations; macrophages are the most common phagocyte. Here we characterize the effects of palmitate, the most common long-chain saturated fatty acid, on the inflammatory response of each layer of the gestational membranes when infected with GBS, using human cell lines and primary human tissue.

Results

Palmitate itself slightly but significantly augments GBS proliferation. Palmitate and GBS co-stimulation synergized to induce many inflammatory proteins and cytokines, particularly IL-1β and matrix metalloproteinase 9 from DSCs, CTBs, and macrophages, but not from AECs. Many of these findings are recapitulated when treating cells with palmitate and a TLR2 or TLR4 agonist, suggesting broad applicability of palmitate-pathogen synergy. Co-culture of macrophages with DSCs or CTBs, upon co-stimulation with GBS and palmitate, resulted in increased inflammatory responses, contrary to previous work in the absence of palmitate. In whole gestational membrane biopsies, the amnion layer appeared to dampen immune responses from the DSC and CTB layers (the choriodecidua) to GBS and palmitate co-stimulation. Addition of the monounsaturated fatty acid oleate, the most abundant monounsaturated fatty acid in circulation, dampened the proinflammatory effect of palmitate.

Discussion

These studies reveal a complex interplay between the immunological response of the distinct layers of the gestational membrane to GBS infection and that such responses can be altered by exposure to long-chain saturated fatty acids. These data provide insight into how metabolic syndromes such as obesity might contribute to an increased risk for GBS disease during pregnancy.

Rapid systematic review on risks and outcomes of sepsis: the influence of risk factors associated with health inequalities

BACKGROUND AND AIMS

Sepsis is a serious and life-threatening condition caused by a dysregulated immune response to an infection. Recent guidance issued in the UK gave recommendations around recognition and antibiotic treatment of sepsis, but did not consider factors relating to health inequalities. The aim of this study was to summarise the literature investigating associations between health inequalities and sepsis.

METHODS

Searches were conducted in Embase for peer-reviewed articles published since 2010 that included sepsis in combination with one of the following five areas: socioeconomic status, race/ethnicity, community factors, medical needs and pregnancy/maternity.

RESULTS

Five searches identified 1,402 studies, with 50 unique studies included in the review after screening (13 sociodemographic, 14 race/ethnicity, 3 community, 3 care/medical needs and 20 pregnancy/maternity; 3 papers examined multiple health inequalities). Most of the studies were conducted in the USA (31/50), with only four studies using UK data (all pregnancy related). Socioeconomic factors associated with increased sepsis incidence included lower socioeconomic status, unemployment and lower education level, although findings were not consistent across studies. For ethnicity, mixed results were reported. Living in a medically underserved area or being resident in a nursing home increased risk of sepsis. Mortality rates after sepsis were found to be higher in people living in rural areas or in those discharged to skilled nursing facilities while associations with ethnicity were mixed. Complications during delivery, caesarean-section delivery, increased deprivation and black and other ethnic minority race were associated with post-partum sepsis.

CONCLUSION

There are clear correlations between sepsis morbidity and mortality and the presence of factors associated with health inequalities. To inform local guidance and drive public health measures, there is a need for studies conducted across more diverse setting and countries.

Placental pathology associated with maternal age and maternal obesity in singleton pregnancy

OBJECTIVE

Maternal age, maternal obesity and neonatal sex dimorphism are known to affect pregnancy and neonatal outcome. However, the effects of these factors on specific placental pathology are less well-documented.

STUDY DESIGN

Clinical information, placental pathology and neonatal data from singleton delivery were collected at our hospital in March 2020 to October 2021 and correlation studies were performed.

RESULTS

A total 3,119 singleton placentas were examined between March 2020 and October 2021 in conjunction with clinical information and neonatal birth data. Advanced maternal age (>35) was significantly associated with a variety of pregnancy complications and placental pathology including preeclampsia/pregnancy induced hypertension (Pre/PIH), gestational diabetes mellitus (GDM2), intrauterine growth restriction (IUGR), and increased maternal body mass index (BMI) at delivery. Maternal obesity (BMI >30 at the time of delivery) was significantly associated with a variety of clinical features and placental pathology including PRE/PIH, GDM2 and decidual vasculopathy (mural arterial hypertrophy). No specific placental pathology was associated with neonatal sex except for more maternal inflammatory response (MIR, chronic deciduitis) in neonates of male sex.

CONCLUSION

Maternal age and maternal obesity were associated with not only clinical complications of pregnancy and neonatal birth weight but also specific placental pathology. Understanding the effects of maternal and environmental factors will help improve pregnancy outcome.

Group B streptococcal infection of the genitourinary tract in pregnant and non-pregnant patients with diabetes mellitus: An immunocompromised host or something more?

Group B Streptococcus (GBS), also known as Streptococcus agalactiae is a Gram-positive bacterium commonly encountered as part of the microbiota within the human gastrointestinal tract. A common cause of infections during pregnancy, GBS is responsible for invasive diseases ranging from urinary tract infections to chorioamnionitis and neonatal sepsis. Diabetes mellitus (DM) is a chronic disease resulting from impaired regulation of blood glucose levels. The incidence of DM has steadily increased worldwide to affecting over 450 million people. Poorly controlled DM is associated with multiple health comorbidities including an increased risk for infection. Epidemiologic studies have clearly demonstrated that DM correlates with an increased risk for invasive GBS infections, including skin and soft tissue infections and sepsis in non-pregnant adults. However, the impact of DM on risk for invasive GBS urogenital infections, particularly during the already vulnerable time of pregnancy, is less clear. We review the evolving epidemiology, immunology, and pathophysiology of GBS urogenital infections including rectovaginal colonization during pregnancy, neonatal infections of infants exposed to DM in utero, and urinary tract infections in pregnant and non-pregnant adults in the context of DM and highlight in vitro studies examining why DM might increase risk for GBS urogenital infection.

Cause-Specific Stillbirth and Neonatal Death According to Prepregnancy Obesity and Early Gestational Weight Gain: A Study in the Danish National Birth Cohort

Maternal obesity is associated with impaired fetal and neonatal survival, but underlying mechanisms are poorly understood. We examined how prepregnancy BMI and early gestational weight gain (GWG) were associated with cause-specific stillbirth and neonatal death. In 85,822 pregnancies in the Danish National Birth Cohort (1996–2002), we identified causes of death from medical records for 272 late stillbirths and 228 neonatal deaths. Prepregnancy BMI and early GWG derived from an early pregnancy interview and Cox regression were used to estimate associations with stillbirth or neonatal death as a combined outcome and nine specific cause-of-death categories. Compared to women with normal weight, risk of stillbirth or neonatal death was increased by 66% with overweight and 78% with obesity. Especially deaths due to placental dysfunction, umbilical cord complications, intrapartum events, and infections were increased in women with obesity. More stillbirths and neonatal deaths were observed in women with BMI < 25 and low GWG. Additionally, unexplained intrauterine death was increased with low GWG, while more early stillbirths were seen with both low and high GWG. In conclusion, causes of death that relate to vascular and metabolic disturbances were increased in women with obesity. Low early GWG in women of normal weight deserves more clinical attention.

Associations between maternal obesity and infectious morbidity in Zimbabwean infants

The prevalence of overweight and obesity is increasing among reproductive-age women in sub-Saharan Africa. Whether maternal body mass index (BMI) influences the risk of infant infections in low- and middle-income countries (LMIC) is uncertain. We used data from a birth cohort of 5344 HIV-unexposed Zimbabwean infants with available data on maternal BMI, to calculate rates of sick clinic visits for infections during the first 12 months postpartum, and adjusted hazard ratios (aHR) for each maternal BMI group. Compared to infants of mothers with normal BMI, the rate of sick clinic visits for any infection progressively rose among infants of overweight (aHR 1.05; 95%CI 0.99, 1.11) and obese women (aHR 1.15; 95%CI 1.05, 1.25). Excess clinic attendances were particularly due to skin, respiratory and ear infections. Maternal obesity may therefore influence infant infectious morbidity in LMIC over the first year after birth.

The Influence of Obesity and Associated Fatty Acids on Placental Inflammation

PURPOSE

Maternal obesity, affecting nearly 1 in 4 pregnancies, is associated with increased circulating saturated fatty acids, such as palmitate. These fatty acids are implicated in placental inflammation, which may in turn exacerbate both maternal-fetal tolerance and responses to pathogens, such as group B Streptococcus. In this review, we address the question, "How do obesity and associated fatty acids influence placental inflammation?"

METHODS

In this narrative review, we searched PubMed and Google Scholar using combinations of the key words placental inflammation or pregnancy and lipids, fatty acids, obesity, palmitate, or other closely related search terms. We also used references found within these articles that may have been absent from our original search queries. We analyzed methods and key results of these articles to compare and contrast their findings, which were occasionally at odds with each other.

FINDINGS

Although obesity can be studied as a whole, complex phenomena with in vivo mouse models and human samples from patients with obesity, in vitro modeling often relies on the treatment of cells or tissues with ≥1 fatty acids and occasionally other compounds (eg, glucose and insulin). We found that palmitate, most commonly used in vitro to recreate hallmarks of obesity, induces apoptosis, oxidative stress, mitochondrial dysfunction, autophagy defects, and inflammasome activation in many placental cell types. We compare this to in vivo models of obesity wherever possible. We found that obesity as a whole may have more complex regulation of these phenomena (apoptosis, oxidative stress, mitochondrial dysfunction, autophagy defects, and inflammasome activation) compared with in vitro models of fatty acid treatment (primarily palmitate) because of the presence of unsaturated fatty acids (ie, oleate), which may have anti-inflammatory effects.

IMPLICATIONS

The interaction of unsaturated fatty acids with saturated fatty acids may ameliorate many inflammatory effects of saturated fatty acids alone, which complicates interpretation of in vitro studies that focus on a particular fatty acid in isolation. This complication may explain why certain studies of obesity in vivo have differing outcomes from studies of specific fatty acids in vitro.