FREE Histamine Guide

Histamine Intolerance and Pregnancy

Morning sickness… Do I need to say more? You are overjoyed that you’re pregnant…only if you could skip the discomfort of having morning sickness. I hear you. I had hyperemesis gravidarum during my pregnancies. It’s morning sickness on steroids. I felt nauseous and was vomiting all the time during my entire pregnancy. I didn’t know back then that it was all because of histamine intolerance. 

Addressing histamine intolerance and MCAS during pregnancy is particularly important. Histamine intolerance can make your morning sickness worse and cause hyperemesis. It can also increase your risk of pre-eclampsia, spontaneous miscarriage, intrauterine growth retardation (IUGR), and preterm labor. Reducing your histamine levels naturally can greatly improve your pregnancy and reduce your risk of discomfort and complications.

In this article, you will learn about the role of histamine in fertility and pregnancy. You will understand histamine’s role before conception and during pregnancy. You will learn about histamine-related pregnancy issues and complications that may occur if you have histamine intolerance or mast cell activation syndrome (MCAS). You will learn how to reduce histamine in your body naturally to ensure a healthy pregnancy and birth.

The Role of Histamine in Fertility and Pregnancy

Proper histamine balance and function is absolutely critical for sexual functions, fertility, and pregnancy. You may not know this, but the embryonic and placental cells use histamine to communicate with each other. The placenta is high in histidine decarboxylase (HDC) and diamine oxidase (DAO) enzymes. It’s no wonder that histamine intolerance may affect your pregnancy.

Histamine’s Role Before Conception

Histamine plays an important role in your cycle and successful pregnancy. It triggers estrogen production in your ovaries and histamine release from your mast cells in your uterus. Progesterone, on the other hand, inhibits the release of histamine. Your endometrial cells use histamine as a messenger to communicate as they prepare for implantation, which causes normal fluctuation of histamine during your menstrual cycle (1, 2).

While histamine is much necessary for your cycle and conception, too much estrogen can become a problem. Excess histamine can lead to increased estrogen and hormonal imbalance, which can lead to a variety of issues. Histamine intolerance can stimulate pain receptors, cause uterine contractions, contribute to menstrual cramps, cause menstrual migraines, and lead to digestive issues. Women with endometriosis may have an increased risk of histamine intolerance or abnormal histamine metabolism, while histamine intolerance or mast cell activation syndrome (MCAS) may increase your risk of endometriosis (3, 4, 5, 6).

Histamine During Pregnancy

Histamine is incredibly important for your healthy menstrual cycle, implantation, and healthy pregnancy. According to a 2-14 study published Pharmaepidemiology Drug Safety, using antihistamine may inhibit implantation and increase the risk of spontaneous abortion (7).

After implantation, your histamine levels increase. Your total blood histamine levels are the highest during the first trimester and gradually decline during the second and third trimester. The reason for this lies in your uterus. The uterine lining, uterine muscles, and placenta are all high in masts cells and HDC enzymes that during this stage increase histamine production in these areas. Histamine also helps the release of the human chorionic gonadotropin (HCG) and other hormones during pregnancy.

Breaking down all this extra histamine is absolutely critical for your health. This is when the DAO enzyme comes in to play an important role. According to a scientific paper published in Agents Action, researchers have found that DAO enzyme levels increase 500 to 1000 times by the first 20 weeks of pregnancy to tackle excess histamine and decrease blood histamine levels. You know those pregnancy food cravings and food aversions?! All the excess histamine may explain your strange new sensitivities, aversions, and cravings. While your histamine levels are the highest during the first trimester, the increase of DAO enzymes only starts to really kick in by the second trimester which may also explain your symptoms going away. (8)

These changes can become even more problematic if you are dealing with histamine intolerance or MCAS already. If you have histamine intolerance or consume too many high-histamine foods, your body won’t be able to keep up with the extra histamine released during pregnancy even with increased DAO enzyme activity. Some women’s bodies may also have an issue with producing enough DAO enzymes, especially if they have histamine intolerance already. Consuming too many DAO-enzyme-blocking foods, such as black tea, energy drinks, mate tea, green tea (green tea extract is ok!), or alcohol, can also interfere with your body’s ability to break down excess histamine.

According to a 2008 review published in Human Reproduction Update, histamine intolerance or an inability to keep histamine in the areas that it is needed can lead to poor pregnancy outcomes. Animal models have found that injecting histamine into pregnant animals leads to a variety of problems, including uterine contraction, spontaneous miscarriage, and fetal malformations (9).

Histamine Intolerance and MCAS During Pregnancy

If you were already dealing with histamine intolerance or MCAS before pregnancy, you may end up with more pregnancy discomfort or complications than those without histamine intolerance or MCAS. You may also develop histamine intolerance during pregnancy. Addressing histamine intolerance and/or MCAS is absolutely critical, not only for your health but your baby’s health as well. Increase histamine levels and the inability to increase placental DAO is associated with an array of health issues, including morning sickness and hyperemesis, pre-eclampsia, increase risk of spontaneous miscarriage, intrauterine growth retardation, and preterm labor. 

Morning Sickness and Hyperemesis

Morning sickness is an experience that most pregnant women are familiar with. It is nausea and vomiting that happens during pregnancy, especially during the first semester. Even though it’s called morning sickness, it can happen at any time during the day or at night, or throughout the day. Some women get through this experience with mild discomfort, for others, it can be a debilitating experience. If you’re like me, you develop hyperemesis gravidarum. 

Hyperemesis gravidarum is like morning sickness but a thousand times worse. While morning sickness is mild or moderate nausea that goes away after the first trimester, hyperemesis is extreme, persistent nausea and vomiting that usually lasts through the entire pregnancy and can lead to dehydration, electrolyte imbalance, and weight loss. While it’s believed to be caused by the rapid rise of the HCG hormone, it may be triggered and increased by histamine intolerance or MCAS. According to a 2006 study published in the Journal of Reproductive Immunology, high blood histamine or hyper-histamine can increase the risk or contribute to the discomfort of hyperemesis gravidarum. A 2008 review published in Human Reproduction Update has also found that increased histamine during pregnancy can increase the risk of hyperemesis gravidarum (10, 9).


Pre-eclampsia is a pregnancy complication characterized by high blood pressure. This dangerously high blood pressure tends to develop after week 20 in women who didn’t previously have blood pressure problems. According to a 1984 study published in Human Nutrition, Clinical Nutrition has found that the total blood histamine level during pregnancy is correlated with the risk of and severity of pre-eclampsia. A 2008 review published in Human Reproduction Update has also found that increased histamine during pregnancy can increase the risk of pre-eclampsia (11, 9).

Spontaneous Miscarriage

Spontaneous miscarriage is a loss of a pregnancy that happens before the first 20 weeks of pregnancy without outside intervention. It is the most common during the first 12 weeks. According to a 1982 study published in the British Journal of Obstetrics & Gynaecologist, measuring DAO enzyme levels in 681 pregnancies with successful delivery and 102 pregnancies resulting in fetal death has shown that low DAO enzyme levels were more common among low birth weight deliveries and pregnancy losses than in healthy pregnancies and births. Low DAO level enzymes were associated with a 16.6 times higher risk of miscarriage at or before 12 weeks. A 2008 review published in Human Reproduction Update has also found that increased histamine during pregnancy can increase the risk of spontaneous miscarriage (12, 9).

Intrauterine Growth Retardation

Intrauterine growth retardation (IUGR) means that your baby is growing slowly and doesn’t weigh as much as most unborn babies at that stage would. IUGR is diagnosed during an ultrasound and is most commonly found during the 6th, 7th, or 8th months of your pregnancy. IUGR refers to slow growth and the size of the baby, it does not refer to mental abilities or mental slowness. Most small babies with IUGR grow up to be healthy children and adults, however, when IUGR is detected, it’s important to rule out any problems and develop strategies to support the baby’s growth. According to a 1999 study published in Inflammation Research, mast cells and histamine during pregnancy can increase the risk of IUGR (13). 

Preterm Labor

Preterm labor refers to labor that happens before 37 weeks of pregnancy. While many premature babies grow up to be healthy children and adults, babies born preterm can have a variety of health issues, including serious, lifelong, or even life-threatening health problems. According to a 2006 study published in the Journal of Reproductive Immunology, material histamine levels can increase the risk of pregnancy complications that may lead to preterm labor (10).

Improve Your Pregnancy with The 4-Phase Histamine Reset Plan

If you have histamine intolerance or MCAS, pregnant, or want to conceive in the future, you don’t have to deal with pregnancy complications. You can reduce your risk of histamine-related debilitating morning sickness, hyperemesis gravidarum, pre-eclampsia, spontaneous miscarriage, IUGR, and preterm labor naturally by following a low-histamine diet and lifestyle. You can feel healthier, more energetic, and vibrant throughout your pregnancy and protect your baby’s health by protecting yours.

To improve histamine intolerance and MCAS and lower your risk of debilitating morning sickness, hyperemesis gravidarum, and other histamine-related pregnancy complications, I recommend that you eat an anti-inflammatory, nutrient-dense, and low-histamine diet. Start by eliminating all histamine foods for one to three months, then slowly re-introduce them one by one following The 4-Phase Histamine Reset Plan

Along with dietary changes, it’s important that you eliminate toxic personal care and cleaning products as well and instead use organic, natural, or homemade products. Additionally, I recommend that you follow a healthy and anti-inflammatory lifestyle that doesn’t trigger increased histamine. Get plenty of sleep. Exercise regularly. Reduce your stress levels through meditation, breathwork, journaling, yoga, time in nature, quality me-time, and uplifting activities with friends and family.

The 4-Phase Histamine Reset Plan is a plan that I developed to help people like you who are dealing with histamine intolerance and related health issues, including morning sickness or hyperemesis. It is a simple yet refined system, so it is critical that you understand and follow each step properly. 

To understand each step and guide your recovery, I recommend that you read my book, The 4-Phase Histamine Reset Plan: Getting to the Root of Migraines, Eczema, Vertigo, Allergies and More where I explain everything about histamine intolerance and each phase of the plan in detail and share delicious low-histamine recipes to nourish your body and support your health. Pick up a copy, today to learn more about the plan and my recommendations.

Check Out the Health Babes’ Guide to Balancing Your Hormones

To learn more about your hormones and learn how to improve your hormonal health naturally, I recommend our book (co-authored by Dr. Krystal Hohn and myself) The Health Babes’ Guide to Balancing Your Hormones: A Detailed Plan with Recipes to Support Mood, Energy Levels, Libido, and More. This book is not only full of information but with an easy-to-follow plan and easy-to-make, delicious hormone-friendly recipes.

Final Thoughts

I felt sick all through time throughout my pregnancy because of hyperemesis gravidarum. I wish I’d known back then that histamine intolerance was the culprit all along. But now I know and I can help your pregnancy to be a better experience than mine. It’s possible to reduce your risk of histamine-related morning sickness, hyperemesis, pre-eclampsia, spontaneous miscarriage, intrauterine growth retardation (IUGR), and preterm labor naturally by following a low-histamine diet and lifestyle. Follow my tips to reduce histamine in your body naturally to ensure a healthy pregnancy and birth.

If you are dealing with histamine intolerance, MCAS, morning sickness, or hyperemesis during your pregnancy, I invite you to schedule a consultation with us. We can help to identify the root cause of your condition and recommend a personalized treatment plan to repair your body and regain your health and well-being. Schedule your consultation here.


Histamine intolerance guide

1. Bódis J, Tinneberg HR, Schwarz H, Papenfuss F, Török A, Hanf V. The effect of histamine on progesterone and estradiol secretion of human granulosa cells in serum-free culture. Gynecol Endocrinol. 1993;7: 235–239. Link Here
2. Vasiadi M, Kempuraj D, Boucher W, Kalogeromitros D, Theoharides TC. Progesterone inhibits mast cell secretion. Int J Immunopathol Pharmacol. 2006;19: 787–794. Link Here
3. Szelag A, Merwid-Lad A, Trocha M. [Histamine receptors in the female reproductive system. Part II. The role of histamine in the placenta, histamine receptors and the uterus contractility]. Ginekol Pol. 2002;73: 636–644. Link Here
4. Rosa AC, Fantozzi R. The role of histamine in neurogenic inflammation. Br J Pharmacol. 2013;170: 38–45. Link Here
5. Maintz L, Benfadal S, Allam J-P, Hagemann T, Fimmers R, Novak N. Evidence for a reduced histamine degradation capacity in a subgroup of patients with atopic eczema. J Allergy Clin Immunol. 2006;117: 1106–1112. Link Here
6. Orazov MR, Radzinskiy VY, Khamoshina MB, Nosenko EN, Tokaeva ES, Barsegyan LK, et al. [Histamine metabolism disorder in pathogenesis of chronic pelvic pain in patients with external genital endometriosis]. Patol Fiziol Eksp Ter. 2017;61: 56–60. Link Here
7. Aldridge TD, Hartmann KE, Michels KA, Velez Edwards DR. First-trimester antihistamine exposure and risk of spontaneous abortion or preterm birth. Pharmacoepidemiol Drug Saf. 2014;23: 1043–1050. Link Here
8. Dubois AM, Santais MC, Foussard C, Dubois F, Ruff F, Taurelle R, et al. Blood histamine and plasma histaminase level during human pregnancy [proceedings]. Agents Actions. 1977;7: 112. Link Here
9. Maintz L, Schwarzer V, Bieber T, van der Ven K, Novak N. Effects of histamine and diamine oxidase activities on pregnancy: a critical review. Hum Reprod Update. 2008;14: 485–495. Link Here
10. Brew O, Sullivan MHF. The links between maternal histamine levels and complications of human pregnancy. J Reprod Immunol. 2006;72: 94–107. Link Here
11. Sharma SC, Sabra A, Molloy A, Bonnar J. Comparison of blood levels of histamine and total ascorbic acid in pre-eclampsia with normal pregnancy. Hum Nutr Clin Nutr. 1984;38: 3–9. Link Here 
12. Gahl WA, Raubertas RF, Vale AM, Golubjatnikov R. Maternal serum diamine oxidase in fetal death and low-birth-weight infants. Br J Obstet Gynaecol. 1982;89: 202–207. Link Here
13. Szukiewicz D, Szukiewicz A, Maslinska D, Poppe P, Gujski M, Olszewski M. Mast cells and histamine in intrauterine growth retardation–relation to the development of placental microvessels. Inflamm Res. 1999;48 Suppl 1: S41–2. Link Here





Hi, I am Dr. Becky Campbell. I work with men and women who’ve had a health set back and are willing to do whatever it takes to reach optimal health so they can perform their best in their careers and be fully present with their family again.