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Anaphylaxis in Pregnancy

Key points

  • Although rare, anaphylaxis during pregnancy can be associated with significant adverse outcomes for both mother and infant and can be fatal.
  • There are published guidelines for the management of anaphylaxis in adults however there is little information about how anaphylactic shock in pregnancy should be managed in order to optimise the outcome for both mother and baby.
  • This study will collect information about the incidence, management and outcomes of anaphylaxis inpregnancy in the UK.

Surveillance Period

October 2012 – September 2015


Anaphylaxis is severe and potentially fatal systemic hypersensitivity reaction. It is characterised by a combination of life-threatening airway, breathing or circulatory problems with skin or mucosal changes. There is always rapid onset and progression of symptoms[1]. Current estimates of incidence suggest that maternal anaphylaxis occurs in approximately 1 in 30,000 pregnancies, although this is based on limited evidence[2]. There is currently no published information relating to the incidence of anaphylaxis during pregnancy available for the UK and although this condition is rare, the importance of studying it is highlighted by a number of case studies showing that anaphylaxis during pregnancy can be associated with significant adverse outcomes for both mother and infant[3][4].

Anaphylaxis can be caused by a wide variety of agents and it is unclear as to whether the risk factors for anaphylaxis in the general population such as age, concomitant co-morbidities and previously documented hypersensitivity can accurately predict risk of anaphylaxis in pregnancy[5]. The recent proposed and actual policy changes with regard to antibiotic administration in pregnancy, including the use of prophylactic antibiotics up to one hour prior to delivery by caesarean section and the use of prophylactic antibiotics for maternal group B streptococcal carriage in labour have the potential to impact on the incidence and/or outcomes of anaphylaxis during pregnancy, making this study very timely.

Beyond adhering to the best practice algorithm for management of anaphylaxis in an adult, there is little known about how anaphylactic shock in pregnancy should be managed in order to optimise the outcome for both mother and baby.

Research questions

  • What is the current incidence of anaphylaxis during pregnancy in the UK?
  • What are the causative agents implicated in anaphylactic reaction during pregnancy?
  • How is anaphylaxis during pregnancy managed in the UK?
  • What are the maternal, fetal and immediate neonatal outcomes following anaphylactic reaction during pregnancy?
  • What are the factors associated with poor outcomes for mother or infant?

Case definition

The cases will be all pregnant women in the UK identified as having anaphylaxis as identified by the following definition[1]:

Anaphylaxis is defined as a severe, life-threatening generalised or systemic hypersensitivity reaction.

  1. A life-threatening airway problem and/or breathing problem and/or circulatory problem
  2. Sudden onset and rapid progression of symptoms
  3. Skin and/or mucosal changes

A life-threatening airway problem is taken to include:

  • Laryngeal or pharyngeal oedema
  • Hoarse voice
  • Stridor

A life-threatening breathing problem is taken to include:

  • Shortness of breath and raised respiratory rate
  • Wheeze
  • Decreased oxygen saturations
  • Confusion secondary to hypoxia
  • Cyanosis
  • Respiratory exhaustion or respiratory arrest

A life-threatening circulatory problem is taken to include:

  • Signs of shock such as faintness, pallor or clammy skin
  • Tachycardia >100bpm
  • Systolic BP <90mmHg
  • Decreasing level of consciousness
  • Signs of ischaemia on ECG
  • Cardiac arrest

Women should not be reported if a diagnosis of anaphylaxis has been excluded by their senior attending clinician.


This study represents independent research commissioned by the National Institute for Health Research (NIHR) under its Programme Grants for Applied Research Programme (Programme Grant RP-PG-0608-100038)

Ethics approval

REC Reference 10/H0717/20

Download the Data Collection Form (DCF)

UKOSS Anaphylaxis in Pregnancy Form


  1. a, b Resuscitation Council (UK). Emergency treatment of anaphylactic reactions; guidelines for healthcare professionals. 2008.
  2. ^ Mulla Z D, Ebrahim M S, Gonzalez J L. Anaphylaxis in the obstetric patient: analysis of a state wide hospital discharge database. Ann Allergy Asthma Immunol (2010); 104: 55-5.
  3. ^ CEDSI Executive Summary of the 7th Annual Report.
  4. ^ Bellis A, Stannard L. Maternal anaphylactic reaction to a general anaesthetic at emergency caesarean section for fetal bradycardia. British Journal of Obstetrics and Gynaecology (2001); 108: 539-540.
  5. ^ Simons F E. Anaphylaxis. Journal of Allergy and Clinical Immunology (2010); 125: 161-181.

Updated: Tuesday, 17 January 2023 17:59 (v7)

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