Mpox in pregnancy: Clinical management and preparedness for a clade I outbreak

The mpox (formerly monkeypox) virus (MPXV) was first identified as a pathogen in non-human primates in 1958 and as a human pathogen in 1970 [1]. The virus came to global attention in 2022, when several cases of human MPXV infection (mpox) were identified in non-endemic countries. Like the Variola (smallpox) virus, the MPXV belongs to the orthopoxvirus genus, with two subtypes: clade I and clade II [1]. Clade I is endemic in the Democratic Republic of Congo (DRC) and human infection carries a mortality rate of 10–15 %, compared with 1–6 % for clade II [2]. Within the United Kingdom, clade I infection is classified as a High Consequence Infectious Disease (HCID) [3]. In March 2025, a total of 50 countries reported 3508 new confirmed cases and 25 new deaths, with 2997 cases reported from the Africa region, 288 cases from the European region, 188 cases from the Americas, 22 cases from the Western Pacific region, 6 from the South East Asian region and 7 cases from the Eastern Mediterranean region [4].

MPXV is spread via droplets, including face-to-face household contact; close physical contact (such as kissing or sexual contact) or sharing bedding/clothing with an active mpox case; and contact with or consumption of infected animals such as monkeys and rodents [5]. Transmission by asymptomatic individuals has also been reported [5]. The incubation period is 5–21 days.

The World Health Organization (WHO) has recorded at least 60 cases of clade II mpox in pregnancy since 2022, with 13 hospitalisations. However, these numbers are likely to be an under-estimate given the paucity of data from endemic areas [2,4]. To date, there have been no reported maternal deaths. One case of postnatal infection with clade II has been reported in the UK, resulting in severe neonatal disease [6]. The implications of mpox in pregnancy are not fully understood, but the similarities with smallpox and the available evidence would suggest that there are likely to be clinically significant maternal, fetal and neonatal consequences. Risks include miscarriage, pre-term birth and stillbirth. Vertical transmission is thought to occur. [2,[5], [6], [7], [8], [9]]

Given globalization, it is inevitable that clade I infections will be reported in more countries and there is a risk of a clade I outbreak in a non-endemic area, with serious implications for public health. Like many other viral infections, mpox is likely to be more severe in pregnant women [2,[6], [7], [8], [9], [10]]. The prevention, early detection and treatment of mpox in pregnancy is therefore a public health priority. As with any other communicable disease, a key aspect of management is the prevention of contagion. The scenario where a pregnant woman with mpox spends a prolonged period in a hospital waiting area mingling with other pregnant women, and is then assessed by unsuspecting clinicians, would cause significant patient anxiety and necessitate contact tracing for patients and quarantine for several clinicians. To minimize the risks, healthcare institutions in general, and maternity services in particular, should have tested procedures for triage, isolation and safe evaluation of suspected cases (Fig. 1). Lessons should be learnt from the COVID-19 pandemic and from strategies regularly deployed during local outbreaks of infectious diarrhoeal illnesses.

Fig. 1.

Initial clinical approach to a suspected MPOX case.

The initial triage should be simple enough to be undertaken by non-clinical hospital reception staff. We propose the use of 2 screening questions by hospital reception staff: (1) Do you have a flu-like illness? (2) Do you have a new rash? A positive answer to either question should prompt the provision of appropriate personal protective equipment (PPE; surgical mask for flu-like symptoms plus a gown and gloves to cover entire rash if appropriate) and isolation in a well-ventilated room for prompt assessment by clinicians wearing appropriate PPE [3,11]. This should be in addition to standard maternity triage procedures. This process would result in the isolation and safe assessment of women with a variety of communicable diseases, including influenza, COVID-19, respiratory syncytial virus, chickenpox and measles. Needless to say, some women with non-communicable diseases will also be isolated.

Clinical assessment begins with a detailed history, including travel history and history of contact with other individuals who might have travelled to an endemic area or suffered a similar illness recently. Otherwise, symptoms of mpox are non-specific and include fever, headache, sore throat, myalgia, arthralgia and generalized malaise [5,12]. Rectal bleeding, dysuria and dysphagia may occur. Many would be familiar with the typical appearance of pustular mpox rash on black skin. However, clinicians should also be familiar with the different stages of rash evolution and the appearance of the rash on lighter skin tones [11] to reduce the risk of misdiagnosis. Non-specific signs of viral illness, including pyrexia and tachycardia, can be expected and there may be lesions in the oral and rectal mucosa plus lymphadenopathy. In severe cases, encephalitis and pneumonitis may occur. Children (including neonates), pregnant women and immunocompromised individuals are at higher risk of severe disease.

The diagnosis is confirmed by the detection of MPXV DNA by polymerase chain reaction (PCR). Samples should be taken from the rash (skin, fluid or crusts) or from the throat or anus if involved, by vigorous swabbing. Use of blood samples for PCR or antibody detection is not recommended [4]. Mpox is difficult to distinguish clinically from, and may co-exist with other infections such as chickenpox, measles, scabies, herpes simplex, syphilis and bacterial skin infections. Simultaneous tests should therefore be undertaken to exclude these conditions. Screening for other sexually transmitted infections should be offered. All positive cases should be notified to the relevant local authorities to enable contact-tracing, isolation and post-exposure prophylaxis where appropriate.

Treatment of mpox in pregnancy requires an effective multidisciplinary team (MDT), including the general practitioner, obstetricians, midwives, infectious diseases and genito-urinary medicine (GUM) physicians and anaesthetists, depending on gestational age and the presence of labour [9]. Hospitalisation is not necessary for mild/moderate cases caused by the clade II strain in otherwise uncomplicated pregnancies. Preferably, management should be by local GUM or infectious diseases teams, with regular community midwifery input. If there are no clinical concerns, these can be telephone appointments.

The woman and her family should isolate at home until no new lesions emerge for 48 h, there are no mouth lesions, and all lesions on exposed skin scab over and scabs fall off [9]. They should avoid contact with any immunosuppressed individuals, pregnant women or children under 12 years, until all lesions (both covered and uncovered) have healed and crusts have fallen off and there are no mucous membrane lesions. Resources should be available to support, and if necessary, enforce isolation orders. Women with severe disease should be managed in an infectious disease unit with input from maternity services unless there are obstetric complications or labour ensues. Treatment is mainly supportive and designed to maintain hydration, treat pyrexia, maintain oxygenation, provide thromboprophylaxis and prevent secondary infection of skin and mucosal lesions [8]. Antiviral therapy may be required but the prescription should be given only after an MDT discussion. Mpox is not an indication for caesarean section (CS). However, CS may be indicated if labour ensues or birth is indicated in the presence of perineal lesions. [9].

Given the possibility of a clade I mpox outbreak in a non-endemic area, a high level of preparedness is recommended for governments, local authorities and healthcare institutions, particularly those caring for high-risk groups such as pregnant women, neonates and children and the immunocompromised. Public and antenatal education campaigns should increase general awareness of the symptoms and signs of mpox and the steps to be taken in the event of a suspected illness. Healthcare institutions, and maternity services in particular, should have triage procedures that enable early identification, isolation and assessment of suspected cases. These should be subjected to regular simulations to ensure effectiveness. For high-risk exposure (clinical staff or pregnant women), post-exposure prophylaxis in the form of the MVA-BN smallpox vaccine should be available and offered within 4–14 days of exposure [12,13]. MVA-BN is non-replicating and considered safe in pregnancy, although use has been reported in under 300 cases. The current PregInPoxVac randomized trial will evaluate its use in pregnancy.