Introduction to psoriasis Psoriasis in pregnancy Clinical features Variation in skin types Complications Treatment Outcome
Psoriasis is a chronic inflammatory skin condition usually characterised by well-demarcated red and scaly plaques on typical parts of the body including the knees, elbows, and lower back.
It can occur on any part of the body and different types of psoriasis are recognised. Pustular psoriasis of pregnancy (impetigo herpetiformis) is a rare variant of pustular psoriasis, usually occurring in the third trimester.
Psoriasis is common in women of reproductive age as three-quarters of patients develop the disease before reaching their 4th decade. It tends to persist lifelong and will generally fluctuate in severity.
For many pregnant women (33–60%), psoriasis improves during pregnancy but for a minority the disease may flare (25%). In the postpartum period, flaring of psoriasis is common (65%).
The severity of psoriasis during pregnancy can improve during pregnancy (40–60%), worsen (10–20%), or remain stable in the remainder.
There are no differences in the clinical features of psoriasis during pregnancy apart from the variation in severity for the individual woman pre-, during, and post-pregnancy.
See Psoriasis for more information.
Plaque psoriasis is the most common type of psoriasis in all racial groups.
Some topical and systemic treatments may harm the baby, so care is needed. The effect of some treatments is unknown. Phototherapy is useful and there is increasing evidence for the use of biologics. Oral photochemotherapy (PUVA) has theoretical mutagenic risk, although detailed studies have not substantiated this, but it is best avoided in pregnancy
Consult the national or regional guidelines on the safety of medicines during pregnancy. For example, in New Zealand sources such as the drug datasheet and New Zealand formulary may be referred to.
Many topical treatments can be used during pregnancy but topical retinoids and dithranol (anthralin) should be avoided.
Topical treatments that could be considered include:
Narrowband ultraviolet light (nUVB) is considered to be safe for pregnant patients. Phototherapy depletes folate so supplementation is recommended.
There are no controlled studies of the use of biologics in pregnant patients. However, there is increasing evidence for the safe and effective use of biologics in moderate to severe psoriasis treatment during pregnancy. Stopping these agents during pregnancy carries a risk of moderate to severe psoriasis flaring. There is less data about some of the newer agents.
Many monoclonal antibodies used in the treatment of psoriasis actively cross the placental barrier especially in the third trimester after organogenesis is complete, resulting in therapeutic levels in the baby. However, certolizumab (a pegylated tumour necrosis alpha inhibitor), crosses the placental barrier passively and is present in negligible or low concentrations in the baby because of its molecular structure, which lacks an Fc moiety. Etanercept (fusion protein including the Fc receptor) is also present in infants at low levels. If it is safe to do so, some dermatologists withhold the biological agent for the last 8 weeks of pregnancy so that infants are born with negligible levels of the administered drug.
Great care needs to be taken with biologics that cross the placental barrier and vaccinating the newborn infant with live/attenuated vaccines including the Bacillus Calmette-Guérin (BCG) vaccine. There is significant potential for harm or death from live/attenuated vaccines in the infant who are immunocompromised due to them having therapeutic levels of the biological agent that their mother is receiving. There are stand down periods in which the infant must not be vaccinated with these agents; this is commonly 6 months or longer.
There are a number of new agents being developed for psoriasis including janus kinase (JAK) inhibitors and tyrosine kinase inhibitors. There is insufficient evidence to base a recommendation at present for their use in pregnancy and they should be avoided.
Many women will only need topical treatments. However, for those women who require systemic treatment such as those with extensive psoriasis, careful judgement needs to be exercised. A balance of the significant adverse effects of untreated psoriasis on maternal wellbeing and conception against the potential risk of systemic agent use must be sought.
