Pregnant woman protected from allergens, symbolizing immune system during pregnancy.

Allergies During Pregnancy: How They Impact Mom and Baby

Mira Elwood in Health & Wellness December 2025 • 4 min read.

"Uncover the surprising ways pregnancy changes your allergic reactions and what it means for your child's health."

Pregnancy brings many changes, and for women with allergies, these changes can be particularly complex. The interplay between allergy and pregnancy involves the immune system, which behaves differently to protect both mother and baby. Interestingly, the similarities between allergic reactions and the maternal-fetal interface – both involve a skewing towards a Th2 immune response – have sparked questions about whether maternal allergies could be beneficial during pregnancy.

While some studies hint at benefits like shorter time to pregnancy and longer gestational periods for allergic mothers, the overall picture remains unclear. Researchers are actively investigating how pregnancy affects the immunity of allergic and non-allergic women, seeking to understand if a strong Th2 environment influences the fetal immune system and the likelihood of postnatal allergies.

New research dives into the effects of maternal allergies on immune responses during pregnancy, looking at how the body's reaction to allergens changes and what impact these changes might have on both mother and child. This article breaks down the findings, offering insights into managing allergies during pregnancy and understanding potential implications for your baby's health.

Decoding Allergy and Pregnancy: What the Research Reveals

Pregnant woman protected from allergens, symbolizing immune system during pregnancy.

A recent study explored how pregnancy modulates the production of cytokines (proteins that regulate immunity) in response to allergens in both allergic and non-allergic women. The study followed 56 pregnant women—20 with allergic symptoms (13 of whom were sensitized) and 36 without (30 of whom were non-sensitized)—collecting blood samples at multiple points during pregnancy and postpartum. Researchers measured levels of various cytokines and chemokines after stimulating the women's immune cells with common allergens (birch and cat), a mitogen (PHA), and tetanus toxoid.

Here’s a breakdown of the key findings:

Allergen-Specific Changes: Birch allergen exposure during pregnancy increased levels of IL-5, IL-13, and CCL17 (all associated with allergic inflammation) in sensitized women. Conversely, cat allergen exposure increased IL-5 and IL-13 in non-sensitized women.
Timing Matters: IFN-γ secretion (an important antiviral and anti-inflammatory cytokine) initially increased in the first trimester but decreased later in pregnancy in response to birch and cat allergens among non-sensitized women.
Allergy Link: Higher levels of IL-4, IL-5, and IL-13 after allergen exposure were linked to both allergic symptoms and sensitization.
Overall Impact: Pregnancy significantly altered the production of key cytokines and chemokines, leading to enhanced Th2 responses (a type of immune response associated with allergies) to specific allergens depending on the mother's allergic status.

These results suggest that pregnancy has a distinct effect on how the body responds to allergens, with the type of response varying depending on whether a woman has allergies and which allergens she's exposed to.

What This Means for You and Your Baby

The research highlights that pregnancy significantly reshapes immune responses, particularly in how allergic and non-allergic women react to allergens. Allergic women exhibited enhanced Th2-associated responses during pregnancy to seasonal allergens like birch, while non-allergic women showed similar increases to perennial allergens like cat dander. This allergen-specific magnification during pregnancy could influence fetal immune development.

While the study didn't explore direct effects on babies, it suggests that the immune environment during pregnancy, especially in allergic mothers, might contribute to an increased risk of allergy development in offspring. It's important to discuss any allergy concerns with your healthcare provider, who can offer personalized advice and strategies.

Ultimately, understanding how pregnancy affects your immune system can empower you to make informed decisions for your health and your baby's. Further research is needed to fully clarify the long-term consequences of these immune shifts, but these findings offer valuable insights for navigating allergy management during pregnancy.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1111/pai.12802, Alternate LINK

Title: Pregnancy Modulates The Allergen-Induced Cytokine Production Differently In Allergic And Non-Allergic Women

Subject: Immunology

Journal: Pediatric Allergy and Immunology

Publisher: Wiley

Authors: Martina S. Abelius, Malin Jedenfalk, Jan Ernerudh, Camilla Janefjord, Göran Berg, Leif Matthiesen, Maria C. Jenmalm

Published: 2017-10-03

Everything You Need To Know

How does pregnancy affect allergic reactions?

Pregnancy significantly alters immune responses, particularly in women with allergies. During pregnancy, the body's reaction to allergens changes. The research indicates that women with allergies may experience enhanced Th2 responses, a type of immune response associated with allergies, when exposed to allergens like birch. This immune shift during pregnancy has potential implications for fetal immune development, influencing the likelihood of postnatal allergies in the child. The specific impact depends on the mother's allergic status and the allergens she is exposed to.

What specific substances did the study measure, and why are they important?

The study measured the production of cytokines and chemokines in response to allergens. Cytokines are proteins that regulate immunity, and chemokines are a type of cytokine. The research focused on women exposed to common allergens like birch and cat, and collected blood samples to measure the levels of these substances. The study found that the allergen exposure during pregnancy could change the levels of specific cytokines. Higher levels of IL-4, IL-5, and IL-13, after allergen exposure, were linked to both allergic symptoms and sensitization.

What is the significance of Th2 responses in this research?

The research explores the role of Th2 responses in the context of allergies and pregnancy. Th2 responses are a type of immune response often associated with allergic inflammation. The study found that allergic women exhibited enhanced Th2-associated responses during pregnancy to seasonal allergens like birch. This shift is significant because the Th2 environment may influence the fetal immune system and the likelihood of postnatal allergies. The findings suggest that pregnancy can magnify these responses, depending on the mother's allergic status and the specific allergens encountered.

How was the research conducted to study allergies during pregnancy?

The study followed 56 pregnant women, including those with and without allergies, to understand how pregnancy impacts allergic reactions. Researchers collected blood samples at different stages of pregnancy and after childbirth. The blood samples were then exposed to common allergens like birch and cat. The researchers measured levels of cytokines and chemokines to understand how these substances change in response to allergens during pregnancy. The research observed allergen-specific changes such as the increase of IL-5, IL-13, and CCL17 in sensitized women exposed to birch allergens.

Does the timing of allergen exposure matter in this context?

The findings suggest that the timing of allergen exposure during pregnancy matters. IFN-γ secretion, an important antiviral and anti-inflammatory cytokine, initially increased in the first trimester but decreased later in pregnancy in response to birch and cat allergens among non-sensitized women. The study found that the type of response to allergens could vary depending on the mother's allergic status. These changes in cytokine production, influenced by both the timing of allergen exposure and the mother's allergic state, highlight the complex interplay between pregnancy and the immune system.