As winter turns to spring, everything revives, branches draw green, willow flutters and flowers compete …… The vibrant spring comes inexorably to everyone. For mothers-to-be who have been wrapped in heavy cotton clothes for a cold winter, it is a good idea to change into light spring clothes while having a good mood in the spring season. However, for delicate babies and sensitive mothers-to-be, in spring, when all kinds of pollen and dust are flying around, many people will have allergic symptoms such as nasal congestion, itchy nose, sneezing and rash, itching, asthma, etc. In heavy cases, they may even develop laryngeal edema and go into shock. Therefore, it has to draw our attention. In the following, we will elaborate on allergies and spring allergies for mothers-to-be. We hope that you will have a clear understanding of them after reading, so that you can prevent them in the first place as much as possible to avoid adverse effects on the mother-to-be and the fetus. What are allergies? Allergy is a kind of allergic reaction of the body, an abnormal reaction to normal substances (allergens), which occurs when allergens come into contact with people with allergies. In the process of allergic reactions, allergic mediators play a direct role, and allergens are the external cause of allergic diseases; while low immunity and oxidative damage to mast cells and basophils by a large number of free radicals are the internal cause of allergies. In layman’s terms, allergy means being allergic to a substance. When you eat, touch or inhale a substance, your body will overreact. Under normal circumstances, the body makes antibodies to protect the body from disease; however, the body of an allergic person will mistake a normally harmless substance for something harmful and produce antibodies, and the substance becomes an “allergen. Medically, allergies are divided into four different types (I-IV) according to their allergic nature. Type I is sometimes referred to as “atopic” or “tachyphylaxis”. For example, the body reacts to insect stings within seconds, animal hair allergies and pollen allergies within minutes, and food allergies within 30 minutes. In contrast, type IV allergies react much more slowly, with symptoms not appearing until a day or several days later. Examples include decorative allergies and many types of occupational allergies. For this reason, they are referred to as “late onset allergic reactions”. The most common allergic reactions include asthma, urticaria, allergic rhinitis, allergic conjunctivitis, dermatitis, etc.