Why Autoimmunity Emerges Postpartum and How to Recognize It

The postpartum period brings dramatic shifts in immune function, hormone levels, and overall health, all of which can influence autoimmune activity.

When Gillian was pregnant with her second child, she started experiencing wrist pain towards the end of her pregnancy. Two weeks after giving birth, she had a hard time straightening out her hands, it was difficult to hold her baby to breastfeed, and she couldn’t snap together cloth diapers. She tried Tylenol and ibuprofen but it didn’t help. 

“The pain was progressing elsewhere,” she said. By week four, she recalled that the pain reached her feet and ankles. “I could no longer walk down the stairs normally,” she said.

“Deep down, I knew something was wrong, but I was really scared to admit it.”

Why Autoimmune Diseases Flare After Childbirth

Gillian’s symptoms ended up being signs of rheumatoid arthritis. The postpartum period can be a common time when symptoms of autoimmunity – either flares of existing disease or new disease – emerge.

Research finds that the risk of developing an autoimmune disease is highest in the first 3 years postpartum and that pregnancy complications increase this risk (1).

During pregnancy, the immune system is relatively suppressed. “This is basically nature’s way of preventing the mother from rejecting the fetus as something foreign,” said Elizabeth Pearce, Professor of Medicine at Boston University Chobanian & Avedisian School of Medicine and an endocrinologist at Boston Medical Center. After the baby is delivered, the immune system gradually returns to its baseline state over the following weeks. “That is a time where we frequently see autoimmune disease [come back].” 

Kecia Gaither, Associate Professor of Clinical Obstetrics and Gynecology at Weill Cornell Medicine and Director of Perinatal Services at NYC Health + Hospitals/Lincoln, notes the role of the rapid decrease in estrogen and progesterone as well as shifts in cortisol and prolactin levels. “The interplay between hormones and immune function in the postpartum period is a key reason why the postpartum period is particularly vulnerable for autoimmune complications,” she added. “There are certain autoimmune diseases that are recognized for their increased risk of onset or flare in the postpartum window, especially within the first year after childbirth.”

Conditions like multiple sclerosis, systemic lupus erythematosus, rheumatoid arthritis, and Crohn’s disease often have higher risk of flares postpartum.

Postpartum Thyroiditis

Postpartum thyroiditis is an autoimmune disease where the thyroid becomes inflamed within one year of delivery (2). Postpartum thyroiditis can present as either thyroid hormones being too high or too low. “The immune system attacks the thyroid and causes some inflammation of the thyroid glands,” said Pearce. “This causes the hormone that’s stored in the gland to leak out into circulation, so the thyroid hormone levels transiently become too high. After a few weeks, the thyroid gland runs out of that pre-formed hormone and since the gland is not functioning properly, thyroid hormone levels may become too low.”

In most patients, thyroid function will normalize after several months.

“Postpartum thyroiditis is quite common,” says Pearce. It occurs in 8% of pregnancies (3). However, she explains that many women don’t have symptoms and it usually resolves spontaneously. Those with symptoms of thyroid excess can be treated with a beta-blocker medication. Pearce mentions that those with symptoms of too little thyroid hormone can be treated with thyroid hormone replacement, but oftentimes, it’s a short-term treatment as most women recover normal thyroid function in a few months.

Postpartum Autoimmune Symptoms to Watch For

In the throes of sleepless nights, hormonal changes, and adjusting to life with a new baby, it can be difficult to know whether symptoms experienced during postpartum are abnormal. This is exactly what Gillian found. When she first started having wrist symptoms, she first thought it was carpal tunnel. She explained, “a lot of the odd symptoms I was experiencing… I chalked it up to pregnancy.” But things got worse and she suspected something was wrong.

“There are a lot of symptoms that are normal to the postpartum period,” said Pearce. “Weight loss, sleeplessness, and heightened anxiety are all pretty common and may be a normal part of the postpartum experience.” However, she noted that joint pain, weight gain, constipation, severe palpitations, and tremors would be red flags for something abnormal.

Another important point is that these symptoms can overlap with other non-autoimmune disorders.

But it’s not super straightforward. For example, fatigue can be a sign of normal postpartum life, postpartum depression, or an autoimmune disease. “It’s important for women to be alert to changes in their body, and if things really don’t seem like they are right, to reach out to a care provider and, and to seek testing and evaluation,” Pearce said.

When Gillian went to the doctor, they ordered blood tests. “All the blood work that they ran was negative,” she said. “The only thing that was abnormal was my rheumatoid factor.” Rheumatoid factors are antibodies that target a person’s own body and are used to help diagnose autoimmune diseases, such as rheumatoid arthritis (4). With Gillian’s new rheumatoid arthritis diagnosis, the next step was to decide on the treatment option.

Breastfeeding Safely with Autoimmune Disease

Gillian’s first treatment was a course of steroids to help calm her symptoms first. “Within 12 hours, I started feeling symptom relief,” she said. She also found ways to make breastfeeding more manageable in the meantime while adjusting to her new medication. She ended up using a wrist brace during feedings and changed breastfeeding positions to keep weight off of her wrist and hands.

Since steroids are intended for short-term use, Gillian needed to find a more long-term option. For rheumatoid arthritis, this option was commonly methotrexate, but this medication is toxic and can make its way into breast milk (5). While this level is low in breastmilk, the drug label recommends not using methotrexate while breastfeeding (6). 

Methotrexate isn’t the only autoimmune therapy that should be avoided during breastfeeding. Others include cyclophosphamide and mycophenolate mofetil. “It’s best to discuss medication safety with providers as not all therapies are compatible,” says Gaither. 

For Gillian, she and her doctor eventually settled on the biologic Enbrel for longer-term treatment. While she started noticing improvements within a week, “I remember thinking it took quite a while before I was a little bit more like myself,” she recalled.

Since her diagnosis, Gillian has been on Enbrel for almost four years and gave birth to her third child. Her experience this time went much smoother under the care of a high-risk OBGYN and having her symptoms under control with a plan in place in case her symptoms flared.

Her advice to new mothers navigating the postpartum period with an autoimmune condition:

“Give yourself grace, and lean into the help. It’s okay to have bad days, and it’s okay to let other people see your vulnerability.” 

GAI does not endorse every view and opinion expressed in the listed resources; they are simply a sample of the resources available on managing life with autoimmune disease and other chronic illnesses.

Sources

1. Article Sources

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   2. Naji Rad S, Deluxe L. (2023). Postpartum Thyroiditis. In StatPearls. StatPearls Publishing.

   3. Keely E. J. (2011). Postpartum thyroiditis: an autoimmune thyroid disorder which predicts future thyroid health. Obstetric medicine, 4(1), 7–11.

   4. Cleveland Clinic. (2024). Rheumatoid factor. Cleveland Clinic.

   5. (2025). Methotrexate. In MotherToBaby | Fact Sheets. Organization of Teratology Information Specialists (OTIS).

   6. Baker, T., Datta, P., Rewers-Felkins, K., & Hale, T. W. (2018). High-Dose Methotrexate Treatment in a Breastfeeding Mother with Placenta Accreta: A Case Report. Breastfeeding medicine. The official journal of the Academy of Breastfeeding Medicine, 13(6), 450–452.