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What Causes You To Have Morning Sickness?

Morning sickness is a common condition seen in pregnant women. The severity varies according to the causes and tolerability of the body against changes of pregnancy. Although exact cause to the condition is not known, however, various reasons are sited for morning sickness.

What Causes You To Have Morning Sickness?

What Causes You To Have Morning Sickness?

Morning sickness is the condition in which the patient experiences nausea and vomiting. Apart from nausea and vomiting, the condition is characterized by the presence of dehydration, weight loss, increased heartbeat and loss of appetite. Following are the causes of morning sickness

Alteration In Hormone Levels. Alteration in hormonal level and the inability of the body to adjust this alteration is regarded as one of the primary reasons for nausea and vomiting of pregnancy. Hormones are required for proper maintenance of the developing fetus and any changes in the natural level may lead to conditions such as miscarriage. The hormone involved in the healthy maintenance of fetus includes estrogen and progesterone.

Reduced Immunity. The immunity of pregnant women is significantly reduced so as to allow the proper development of the fetus. If the body maintains the normal immunity level, the fetus may encounter the allergic reaction as it may attack the tissues of the fetus and may lead to miscarriage or stillbirth. However, the body has chosen another route to protect the fetus and mother from infection. The vomiting is the part of such a process which indicates that if any irritating substance enters the body, it will be ejected out of the body through vomiting. Thus, vomiting and nausea are the part of protecting mother and fetus from infection and toxins.

Irritating Odor. The vomiting center of pregnant women is hyperactive due to compromised immunity. Thus, the vomiting may occur due to the slightest of the trigger. Odor, which was not a trigger to the same woman prior to pregnancy, may lead to cause nausea and vomiting due to hyperactive vomiting center. Thus, the irritating odor may also be the reason for morning sickness.

Reduced Blood Sugar Level. Hypoglycemia or low blood sugar level is also the reason for morning sickness and vice versa. There are other reasons which may also cause hypoglycemia during pregnancy. These causes include lifestyle changes, medications, other medical conditions, diabetes, and gestational diabetes. The patient suffering from low blood sugar feels dull and experiences fatigue which may lead to morning sickness. In contrast, increased vomiting also leads to hypoglycemia as the body is deprived of high caloric diet which has been rejected by the body through vomiting.

Genetics. Recent studies have concluded that morning sickness has also been linked with genes. A code for protein, GDF15, is produced in a large amount during the first few weeks of pregnancy, which can be linked to nausea and vomiting. This can be seen as an evolutionary process wherein the body tries to protect the fetus from u wanted toxins that the mother may take during the development of vital organs.

Deficiency Of Vitamins In pregnancy. The nutritional requirement of the mother is significantly increased as the essential nutrients are required by both mother and fetus.

This sometimes results in the deficiency of certain nutritional substances, leading to nausea and vomiting. Deficiency of various vitamins such as thiamine and pyridoxine may be responsible for morning sickness because studies indicate that supplementing the pregnant women with these vitamins improved the condition of morning sickness.

Allergy. Allergic reactions are another cause for morning sickness. The allergic reaction may be caused due to chemicals such as increased hormonal level or due to tissues such as the presence of corpus luteum.

Psychological Cause. Psychological effects such as fear of pregnancy and labor may be another factor that may increase the severity of morning sickness.


Morning sickness may be caused due to altered hormonal level, low blood sugar, reduced immunity, allergic reactions, irritant odor and genetics.


  1. American College of Obstetricians and Gynecologists (ACOG). (2018). Morning Sickness: Nausea and Vomiting of Pregnancy. https://www.acog.org/womens-health/faqs/morning-sickness-nausea-and-vomiting-of-pregnancy
  2. National Institute of Child Health and Human Development (NICHD). (2019). Nausea and Vomiting of Pregnancy. https://www.nichd.nih.gov/health/topics/morning-sickness/conditioninfo/causes
  3. Harvard Health Publishing. (2019). Understanding and Managing Nausea and Vomiting in Pregnancy. https://www.health.harvard.edu/blog/understanding-and-managing-nausea-and-vomiting-in-pregnancy-2019061316843
  4. American Pregnancy Association. (2019). Morning Sickness: Causes, Concerns, Remedies, and Tips. https://americanpregnancy.org/pregnancy-health/morning-sickness-causes-and-treatments/
  5. Louis, G.M.B., et al. (2018). Genetic determinants of nausea and vomiting of pregnancy and hyperemesis gravidarum. European Journal of Obstetrics & Gynecology and Reproductive Biology, 230, 132-137. https://pubmed.ncbi.nlm.nih.gov/30125797/

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Team PainAssist
Team PainAssist
Written, Edited or Reviewed By: Team PainAssist, Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:August 16, 2023

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