Sepsis in obese pregnant women (concise version)

42.1

Introduction

The terms “overweight” and “obesity” are defined by the World Health Organisation (WHO) as an abnormal or excessive fat accumulation that presents a risk to health. Obesity is further classified into three categories: Class 1 (BMI 30.0–34.9 kg/m ² ), Class 2 (BMI 35–39.9 kg/m ² ) and Class 3 or morbid obesity (BMI >40.0 kg/m ² ). Animal, epidemiological and limited human studies have reported that obesity increases susceptibility to both bacterial and viral infections. There is increasing evidence of the increased risk of sepsis in association with obesity in pregnancy.

Obesity is now one of the most frequently occurring obstetric comorbidities with 21.3% of the UK antenatal population obese at booking. Maternal sepsis is defined by the WHO as a “life threatening condition defined as organ dysfunction resulting from infection during pregnancy, childbirth, postabortion, or postpartum period.” The most recent Mothers and Babies: Reducing Risk through Audit and Confidential Enquiries Across the UK (MBRRACE-UK) Report (November 2018) highlights that more than a third of maternal deaths occurred in women classified as obese. Obesity has been recognised as an independent risk factor for both infection and sepsis in pregnancy and this chapter will discuss the epidemiology, immunology, infection sites, management and specific intra and postpartum care of obese pregnant woman with infection.

42.2

Epidemiology of obesity and sepsis

Obesity is a global epidemic affecting both developed and developing countries. The rate of obesity worldwide has tripled since 1975 and the United Kingdom has one of the highest obesity rates in the world at 27%.

Risk factors for obesity include social deprivation, age >35 years, ethnic minorities, regional location and diabetes mellitus.

Obesity in pregnancy : 21.3% are obese at booking with one in two overweight and one in 20 having BMI >35.

The higher a woman’s booking BMI, the greater the risk of adverse perinatal outcomes, including the risk of ICU admission and death.

Table 42.1 summarises MBRRACE-UK, UK Obstetric Surveillance System (UKOSS) and Confidential Enquiry into Maternal and Child Health (CEMACH) reported findings regarding the epidemiology of sepsis in obese patients.

Potential for improvements in care leading to better outcomes and avoidable harm is emphasised by these reports: clinical guidelines, care bundles and annually audited skills and drills sessions have been employed in the hope to improve care. Multidisciplinary care is crucial.

42.3

Immunology

Adipose tissue is known to have both endocrine, steroidogenesis and immunological function. Mechanism of dysregulation of the immune system in obesity is yet to be established but there is clear evidence that adipose tissue causes immunosuppression. Mechanisms include suppressed function of both CD4 and CD8 T cells, T cell diversity, impaired NK cells, decreased cytokine production, disrupted lymphoid tissue architecture , alterations in leucocyte coordination and function , failure to coordinate innate and adaptive immune responses , dysfunction of thymus and spleen and inhibited effectiveness of vaccines.

Table 42.2 summarises these effects,

42.4

Specific infections

There are numerous associated risk factors that put an obese woman at risk of an infection , including anaemia, diabetes mellitus, operative deliveries, cervical cerclage, amniocentesis, Group B streptococcus (GBS) carriage, manual removal of placenta, black or ethnic minorities, young age, multiparity, preterm birth, induction of labour, immunosuppression and ruptured membranes.