Introduction 

PUPPP, an acronym for pruritic urticarial papules and plaques of pregnancy, is one of the most common skin rashes that can occur during pregnancy. Although it is considered harmless and resolves on its own after delivery, it can be quite uncomfortable.

Research has observed that PUPPP tends to occur more often in people carrying twins or triplets, and in pregnancies achieved through assisted conception techniques such as in vitro fertilisation (IVF), which, when it was first introduced, resulted in significantly higher rates of multiple pregnancies. One possible explanation is that multiple pregnancies often lead to greater stretching of the abdomen and higher levels of hormones like progesterone, which may play a role in triggering the rash.¹

If you have ever wondered why this rash shows up in some pregnancies and not others, or why it is more common with twins or triplets, this article breaks it down. From what it feels like to what might cause it, here is what you should know about PUPPP.

What is PUPPP rash?

PUPPP, also called polymorphic eruption of pregnancy (PEP), is a skin condition some people experience during pregnancy. It is the most common pregnancy-related rash.² While it does not harm the mother or baby, it can be itchy and uncomfortable. 

It develops in the third trimester and is more common in first-time pregnancies. The rash usually starts as small, red bumps around stretch marks on the belly. Over time, it can spread to areas like the thighs, buttocks, and arms, but it rarely shows up on the face, palms, or soles.

Though it can be uncomfortable, PUPPP is not something to worry about. It tends to go away on its own after childbirth and does not leave any marks or scars. In most cases, it does not come back in future pregnancies either.¹

What does PUPPP rash look like?

The rash usually begins as small, red, itchy bumps that appear on stretch marks on the belly. From there, it can spread to other areas, such as the thighs, buttocks, and occasionally the arms or chest. The rash rarely spreads to the face, hands, and feet.

As it develops, the bumps may become larger and form raised patches that look swollen. Some people notice pale rings around the rash, and over time, it might change in appearance, showing up as red patches, tiny spots, or dry, irritated areas.

It does not affect the mouth or other moist areas of the body. Most of the time, the rash fades within a few weeks, either on its own or after giving birth, and it does not leave scars or recur in later pregnancies.³

What causes PUPPP rash?

Although scientists have not yet determined the exact cause of PUPPP, they have made some observations and suggested a few possible explanations:

Abdominal distension

This refers to the stretching of the belly as pregnancy progresses. In pregnancies involving twins or triplets, the skin is stretched even more than usual. This can lead to minor damage in the connective tissues within stretch marks. When deeper layers of the skin (which contain collagen) are damaged, an inflammatory response may be triggered by the body, resulting in a rash developing.

Hormonal changes

Pregnancy comes with a series of hormonal changes. There is an increase in the level of progesterone, especially in multiple pregnancies and pregnancies achieved through IVF, which require prolonged progesterone treatment. Scientists have discovered that most people with PUPPP have higher levels of this hormone, suggesting it may play a role in the rash, though further research is required to understand the exact role of progesterone in PUPPP.⁴

Placental factors

One study suggests hormone-like substances produced by the placenta, which is normally larger in multiple pregnancies, may trigger an inflammatory response in the mother’s skin, resulting in PUPPP.¹ 

Fetal DNA (microchimerism)

Later in pregnancy, small amounts of the baby’s DNA can pass into the mother’s blood circulation. The number of cells containing the baby’s DNA increases in multiple pregnancies, possibly reaching areas of the skin that are already stretched or irritated, and potentially triggering an inflammatory response.¹ 

Although none of these theories have been confirmed with certainty, they offer possible explanations for why PUPPP tends to occur more frequently in twin or triplet pregnancies, or pregnancies achieved through IVF.¹

Why is PUPPP rash more common in multiple pregnancies?

PUPPP tends to occur more frequently in multiple pregnancies. Studies have shown that while about 0.5% of people with singleton pregnancies develop PUPPP, the incidence rises to between 2.9% and 16% in twin pregnancies and up to 14–17% in triplet pregnancies.¹

Several factors may contribute to this increased occurrence:

Elevated progesterone levels 

In multiple pregnancies, such as twins or triplets, the body produces higher levels of progesterone compared to a singleton pregnancy. Research shows that progesterone levels are notably elevated in patients with PUPPP. Scientists believe that this hormone, which plays a vital role in maintaining pregnancy, contributes to the development of the rash. Higher progesterone levels in multiple pregnancies may lead to increased skin sensitivity, making 

people carrying twins or triplets more susceptible to PUPPP rash. This explains why the incidence of PUPPP is significantly higher in multiple pregnancies compared to single pregnancies.⁴

Greater abdominal stretching 

Carrying more than one baby, as in the case of twins or triplets, leads to increased abdominal expansion. This rapid stretching places more strain on the skin, especially around stretch marks, which are common in multiple pregnancies. 

The skin’s connective tissues, particularly within these stretch marks, can become damaged due to the rapid growth. As a result, deeper skin components, such as collagen, may be damaged, triggering an inflammatory response. This reaction is believed to be a key factor in the development of the itchy rash characteristic of PUPPP. The increased skin tension in multiple pregnancies may make the body more prone to this rash, which explains why people carrying twins or triplets are more likely to develop PUPPP compared to those with a single pregnancy.

Increased maternal weight gain 

Those carrying multiple pregnancies, such as twins or triplets, typically gain more weight than those with single pregnancies. A study reported that total pregnancy weight gain was 2.0 kg higher in twin pregnancies compared with singletons (17 kg vs 15 kg, respectively).⁵ This additional weight can lead to greater abdominal stretching, which may damage the skin's connective tissues and could potentially trigger the itchy rash seen in PUPPP.

Some studies have also found that people who develop PUPPP tend to gain more weight than those who don’t. For instance, one study observed that about 75% of people with PUPPP had excessive maternal weight gain.⁶ Another study also reported a significant link between greater weight gain and the development of PUPPP rash.¹

This could help explain why people with multiple pregnancies, like twins or triplets, are more likely to develop PUPPP.

How is PUPPP rash treated?

There is currently no cure for PUPPP rash. Treatment focuses on easing the symptoms, especially the intense itching. 

Most cases are managed with topical corticosteroid creams and oral antihistamines. First-generation antihistamines that cause drowsiness, like diphenhydramine, are generally considered safe during pregnancy and may also help with sleep.

In more severe cases, especially when the itching affects sleep or causes exhaustion, a doctor may prescribe a short course of systemic corticosteroids. This helps to calm the inflammation and provide quick relief.

Beyond medications, simple general measures can also make a big difference. Cool, soothing baths help reduce discomfort. Applying moisturisers or emollients keeps the skin hydrated and reduces irritation. Wearing loose, light cotton clothing can prevent friction and allow the skin to breathe.

Most people notice that the rash goes away on its own shortly after delivery. However, in rare postpartum cases where symptoms persist, an intramuscular injection of the patient’s own blood (autologous serum) has been used as an alternative approach, although this is not a standard treatment.²

Overall, the goal of treatment is to help pregnant people feel more comfortable and get better rest while waiting for the rash to resolve naturally, which is usually after childbirth.

FAQs

Is PUPPP rash harmful to my baby?

PUPPP rash is not harmful to your baby. It only affects you, the mother, and does not pose any risk to your baby’s health or development. The rash is caused by factors related to pregnancy, like hormonal changes and abdominal stretching, but it won't affect your baby.

How to treat PUPPP rash?

To treat PUPPP rash, the focus is on relieving symptoms. You can use topical corticosteroids like hydrocortisone to reduce inflammation and oral antihistamines like cetirizine to manage the itching. If the itching disrupts your sleep, sedating antihistamines like diphenhydramine can help you rest. In more severe cases, your doctor may prescribe a short course of systemic corticosteroids, like prednisone, to reduce inflammation and provide relief. Always follow your doctor’s guidance for the best treatment.

Does the baby’s gender affect the likelihood of PUPPP rash?

Some believe PUPPP rash is more common with male babies, but studies have not confirmed this. Factors like multiple pregnancies, weight gain, and hormonal changes play a bigger role in the development of PUPPP.

Summary

PUPPP, or pruritic urticarial papules and plaques of pregnancy, is a common skin rash that some experience during pregnancy. It is especially likely to appear in people who are expecting twins or triplets. While not harmful to mother or baby, it can be very uncomfortable. Experts believe that the increased stretching of the belly, higher hormone levels, and greater weight gain that often happen in multiple pregnancies may all play a role in causing the rash. These changes can irritate the skin and lead to inflammation, which shows up as a red, bumpy rash. Fortunately, PUPPP usually goes away on its own after the baby is born. In the meantime, treatments like soothing creams, antihistamines, and other comfort measures can help manage the itching. While it can be frustrating, PUPPP is temporary, and with proper care and symptom relief, most recover fully, especially after giving birth.