Morning sickness
Encyclopedia
Morning sickness, also called nausea gravidarum, nausea
, vomiting
of pregnancy
(emesis gravidarum or NVP), or pregnancy sickness is a condition that affects more than half of all pregnant women. Related to increased oestrogen levels, a similar form of nausea is also seen in some women who use hormonal contraception
or hormone replacement therapy
. Sometimes it is present in the early hours of the morning and reduces as the day progresses. The nausea can be mild or induce actual vomiting, however, not severe enough to cause metabolic derangement. In more severe cases, vomiting may cause dehydration
, weight loss, alkalosis
and hypokalemia
. This condition is known as hyperemesis gravidarum
and occurs in about 1% of all pregnancies. Nausea and vomiting can be one of the first signs of pregnancy and usually begins around the 6th week of pregnancy (counting gestational age
from 14 days before conception). In spite of its common name, it can occur at any time of the day, and for most women it may stop around the 12th week of pregnancy.
that protects the fetus against toxin
s ingested by the mother.
Many plants contain chemical toxins that serve as a deterrent to being eaten. Adult humans, like other animals, have defenses against plant toxins, including extensive arrays of detoxification enzyme
s manufactured by the liver
and the surface tissues of various other organs. In the fetus, these defenses are not yet fully developed, and even small doses of plant toxins that have negligible effects on the adult can be harmful or lethal to the embryo. Pregnancy sickness causes women to experience nausea when exposed to the smell or taste of foods that are likely to contain toxins injurious to the fetus, even though they may be harmless to her.
There is considerable evidence in support of this theory, including:
Women who have no morning sickness are more likely to miscarry
. This may because such women are more likely to ingest substances that are harmful to the fetus.
In addition to protecting the fetus, morning sickness may also protect the mother. Pregnant women's immune system
s are suppressed during pregnancy, it is presumed to reduce the chances of rejecting
tissues of their own offspring. Because of this, animal products containing parasites and harmful bacteria can be especially dangerous to pregnant women. There is evidence that morning sickness is often triggered by animal products including meat and fish.
If morning sickness is a defense mechanism against the ingestion of toxins, the prescribing of anti-nausea medication to pregnant women may have the undesired side effect
of causing birth defects or miscarriages by encouraging harmful dietary choices. On the other hand, many domestic vegetables have been purposely bred
to have lower levels of toxins than in the distant past, and so the level of threat to the embryo may not be as high as it was when the defense mechanism first evolved.
A doctor may prescribe anti-nausea
medications if the expectant mother suffers from dehydration or malnutrition as a result of her morning sickness, a condition known as hyperemesis gravidarum
. In the US, Zofran (ondansetron
) is the usual drug of choice, though the high cost is prohibitive for some women; in the UK, older drugs with which there is a greater experience of use in pregnancy are preferred, with first choice being promethazine
otherwise as second choice metoclopramide
, or prochlorperazine
. When all other treatments fail, doctors may consider trying a corticosteroid medication such as methylprednisolone. This medication can be given orally or intravenously. It should not be used before 10 weeks gestation because of a small risk that it could cause a cleft lip or palate in the fetus. Because of possible maternal complications, the medicine should not be used for longer than six weeks.
was originally developed and prescribed as a cure for morning sickness in West Germany
, but its use was discontinued when it was found to cause birth defect
s. The United States
Food and Drug Administration
never approved thalidomide for use as a cure for morning sickness.
Nausea
Nausea , is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It often, but not always, precedes vomiting...
, vomiting
Vomiting
Vomiting is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose...
of pregnancy
Pregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...
(emesis gravidarum or NVP), or pregnancy sickness is a condition that affects more than half of all pregnant women. Related to increased oestrogen levels, a similar form of nausea is also seen in some women who use hormonal contraception
Hormonal contraception
Hormonal contraception refers to birth control methods that act on the endocrine system. Almost all methods are composed of steroid hormones, although in India one selective estrogen receptor modulator is marketed as a contraceptive. The original hormonal method—the combined oral contraceptive...
or hormone replacement therapy
Hormone replacement therapy (menopause)
Hormone replacement therapy is a system of medical treatment for surgically menopausal, perimenopausal and to a lesser extent postmenopausal women...
. Sometimes it is present in the early hours of the morning and reduces as the day progresses. The nausea can be mild or induce actual vomiting, however, not severe enough to cause metabolic derangement. In more severe cases, vomiting may cause dehydration
Dehydration
In physiology and medicine, dehydration is defined as the excessive loss of body fluid. It is literally the removal of water from an object; however, in physiological terms, it entails a deficiency of fluid within an organism...
, weight loss, alkalosis
Alkalosis
Alkalosis refers to a condition reducing hydrogen ion concentration of arterial blood plasma . Generally, alkalosis is said to occur when pH of the blood exceeds 7.45. The opposite condition is acidosis .-Causes:...
and hypokalemia
Hypokalemia
Hypokalemia or hypokalaemia , also hypopotassemia or hypopotassaemia , refers to the condition in which the concentration of potassium in the blood is low...
. This condition is known as hyperemesis gravidarum
Hyperemesis gravidarum
Hyperemesis gravidarum is a severe form of morning sickness, with "unrelenting, excessive pregnancy-related nausea and/or vomiting that prevents adequate intake of food and fluids." Hyperemesis is considered a rare complication of pregnancy but, because nausea and vomiting during pregnancy exist...
and occurs in about 1% of all pregnancies. Nausea and vomiting can be one of the first signs of pregnancy and usually begins around the 6th week of pregnancy (counting gestational age
Gestational age
Gestational age relates to the age of an embryo or fetus . There is some ambiguity in how it is defined:*In embryology, gestational age is the time elapsed since conception. This interval is also termed fertilisation age....
from 14 days before conception). In spite of its common name, it can occur at any time of the day, and for most women it may stop around the 12th week of pregnancy.
Causes
Proximate causes of pregnancy sickness include:- An increase in the circulating level of the hormoneHormoneA hormone is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. Only a small amount of hormone is required to alter cell metabolism. In essence, it is a chemical messenger that transports a signal from one...
estrogenEstrogenEstrogens , oestrogens , or œstrogens, are a group of compounds named for their importance in the estrous cycle of humans and other animals. They are the primary female sex hormones. Natural estrogens are steroid hormones, while some synthetic ones are non-steroidal...
. Estrogen levels may increase by up to a hundredfold during pregnancy. However, there is no consistent evidence of differences in estrogen levels and levels of bilirubinBilirubinBilirubin is the yellow breakdown product of normal heme catabolism. Heme is found in hemoglobin, a principal component of red blood cells. Bilirubin is excreted in bile and urine, and elevated levels may indicate certain diseases...
between women that experience sickness and those that do not. - Low blood sugar (hypoglycemiaHypoglycemiaHypoglycemia or hypoglycæmia is the medical term for a state produced by a lower than normal level of blood glucose. The term literally means "under-sweet blood"...
) due to the placentaPlacentaThe placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. "True" placentas are a defining characteristic of eutherian or "placental" mammals, but are also found in some snakes and...
's draining energy from the mother, though studies have not confirmed this. - An increase in progesteroneProgesteroneProgesterone also known as P4 is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy and embryogenesis of humans and other species...
relaxes the muscleMuscleMuscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
s in the uterusUterusThe uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
, which prevents early childbirthChildbirthChildbirth is the culmination of a human pregnancy or gestation period with the birth of one or more newborn infants from a woman's uterus...
, but may also relax the stomachStomachThe stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects , and molluscs. It is involved in the second phase of digestion, following mastication .The stomach is...
and intestineIntestineIn human anatomy, the intestine is the segment of the alimentary canal extending from the pyloric sphincter of the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine...
s, leading to excess stomach acids and gastroesophageal reflux diseaseGastroesophageal reflux diseaseGastroesophageal reflux disease , gastro-oesophageal reflux disease , gastric reflux disease, or acid reflux disease is chronic symptoms or mucosal damage caused by stomach acid coming up from the stomach into the esophagus...
. - An increase in human chorionic gonadotropinHuman chorionic gonadotropinHuman chorionic gonadotropin or human chorionic gonadotrophin is a glycoprotein hormone produced during pregnancy that is made by the developing embryo after conception and later by the syncytiotrophoblast .. Some tumors make this hormone; measured elevated levels when the patient is not...
. It is probably not the human chorionic gonadotropin itself that causes the nausea. More likely, it is the human chorionic gonadotropin-stimulating the maternal ovaries to secrete estrogen, which in turn causes the nausea. - An increase in sensitivitySensitivity (human)The sensitivity or insensitivity of a human, often considered with regard to a particular kind of stimulus, is the strength of the feeling it results in, in comparison with the strength of the stimulus...
to odorOdorAn odor or odour is caused by one or more volatilized chemical compounds, generally at a very low concentration, that humans or other animals perceive by the sense of olfaction. Odors are also commonly called scents, which can refer to both pleasant and unpleasant odors...
s, which overstimulates normal nausea triggers. - An increase in bilirubin levels due to increased liver enzymes.
Morning sickness as a defense mechanism
Morning sickness is currently believed to be an evolved traitNatural selection
Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....
that protects the fetus against toxin
Toxin
A toxin is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded...
s ingested by the mother.
Many plants contain chemical toxins that serve as a deterrent to being eaten. Adult humans, like other animals, have defenses against plant toxins, including extensive arrays of detoxification enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
s manufactured by the liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
and the surface tissues of various other organs. In the fetus, these defenses are not yet fully developed, and even small doses of plant toxins that have negligible effects on the adult can be harmful or lethal to the embryo. Pregnancy sickness causes women to experience nausea when exposed to the smell or taste of foods that are likely to contain toxins injurious to the fetus, even though they may be harmless to her.
There is considerable evidence in support of this theory, including:
- Morning sickness is very common among pregnant women, which argues in favor of its being a functional adaptation and against the idea that it is a pathologyPathologyPathology is the precise study and diagnosis of disease. The word pathology is from Ancient Greek , pathos, "feeling, suffering"; and , -logia, "the study of". Pathologization, to pathologize, refers to the process of defining a condition or behavior as pathological, e.g. pathological gambling....
. - Fetal vulnerability to toxins peaks at around 3 months, which is also the time of peak susceptibility to morning sickness.
- There is a good correlation between toxin concentrations in foods, and the tastes and odors that cause revulsion.
Women who have no morning sickness are more likely to miscarry
Miscarriage
Miscarriage or spontaneous abortion is the spontaneous end of a pregnancy at a stage where the embryo or fetus is incapable of surviving independently, generally defined in humans at prior to 20 weeks of gestation...
. This may because such women are more likely to ingest substances that are harmful to the fetus.
In addition to protecting the fetus, morning sickness may also protect the mother. Pregnant women's immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
s are suppressed during pregnancy, it is presumed to reduce the chances of rejecting
Transplant rejection
Transplant rejection occurs when transplanted tissue is rejected by the recipient's immune system, which destroys the transplanted tissue. Transplant rejection can be lessened by determining the molecular similitude between donor and recipient and by use of immunosuppressant drugs after...
tissues of their own offspring. Because of this, animal products containing parasites and harmful bacteria can be especially dangerous to pregnant women. There is evidence that morning sickness is often triggered by animal products including meat and fish.
If morning sickness is a defense mechanism against the ingestion of toxins, the prescribing of anti-nausea medication to pregnant women may have the undesired side effect
Side effect
In medicine, a side effect is an effect, whether therapeutic or adverse, that is secondary to the one intended; although the term is predominantly employed to describe adverse effects, it can also apply to beneficial, but unintended, consequences of the use of a drug.Occasionally, drugs are...
of causing birth defects or miscarriages by encouraging harmful dietary choices. On the other hand, many domestic vegetables have been purposely bred
Plant breeding
Plant breeding is the art and science of changing the genetics of plants in order to produce desired characteristics. Plant breeding can be accomplished through many different techniques ranging from simply selecting plants with desirable characteristics for propagation, to more complex molecular...
to have lower levels of toxins than in the distant past, and so the level of threat to the embryo may not be as high as it was when the defense mechanism first evolved.
Treatments
There is no evidence to demonstrate the effectiveness of treatments for morning sickness. Suggested treatments typically aim to lessen the symptoms of nausea, rather than attacking the root cause(s) of the nausea. Treatments include:- Wearing acupressure wristbands to stimulate the "Nei-Kuan" acupuncture point on your wrist.
- Lemons, in particular the smelling of freshly cut lemons.
- Avoiding an empty stomach.
- Accommodating food cravings and aversions.
- Eating five or six small meals per day, rather than three large ones.
- Eating cabbage.
- GingerGingerGinger is the rhizome of the plant Zingiber officinale, consumed as a delicacy, medicine, or spice. It lends its name to its genus and family . Other notable members of this plant family are turmeric, cardamom, and galangal....
, in capsules, teaTeaTea is an aromatic beverage prepared by adding cured leaves of the Camellia sinensis plant to hot water. The term also refers to the plant itself. After water, tea is the most widely consumed beverage in the world...
, ginger aleGinger aleGinger ale is a carbonated soft drink flavored with ginger. Dr. Thomas Cantrell, an American apothecary and surgeon, claimed to have invented ginger ale and marketed it with beverage manufacturer Grattan and Company. Grattan embossed the slogan "The Original Makers of Ginger Ale" on its bottles...
, or ginger snapsGinger SnapsGinger Snaps is a 2000 Canadian werewolf film directed by John Fawcett. The film focuses on two teenage sisters, Ginger and Brigitte Fitzgerald , who have a fascination with death. The title is a pun on the cookie Gingersnap. "Snap" also relates to losing one's self-control, or a quick, aggressive...
. Prepare ginger tea by putting ginger shreds in a glass of hot water. Take sips of the tea until nausea is relieved. Ginger candy and capsules are also great alternatives to stop nausea. - Eating dry crackers in the morning. Some women benefit from eating crackers before rising out of bed in the morning.
- Drinking liquids 30 to 45 minutes after eating solid food.
- If liquids are vomited, sucking ice cubes made from water or fruit juice or trying lollipops.
A doctor may prescribe anti-nausea
Antiemetic
An antiemetic is a drug that is effective against vomiting and nausea. Antiemetics are typically used to treat motion sickness and the side effects of opioid analgesics, general anaesthetics, and chemotherapy directed against cancer....
medications if the expectant mother suffers from dehydration or malnutrition as a result of her morning sickness, a condition known as hyperemesis gravidarum
Hyperemesis gravidarum
Hyperemesis gravidarum is a severe form of morning sickness, with "unrelenting, excessive pregnancy-related nausea and/or vomiting that prevents adequate intake of food and fluids." Hyperemesis is considered a rare complication of pregnancy but, because nausea and vomiting during pregnancy exist...
. In the US, Zofran (ondansetron
Ondansetron
Ondansetron is a serotonin 5-HT3 receptor antagonist used mainly as an antiemetic , often following chemotherapy. Its effects are thought to be on both peripheral and central nerves...
) is the usual drug of choice, though the high cost is prohibitive for some women; in the UK, older drugs with which there is a greater experience of use in pregnancy are preferred, with first choice being promethazine
Promethazine
Promethazine is a first-generation antihistamine of the phenothiazine family. The drug has anti-motion sickness, antiemetic, and anticholinergic effects, as well as a strong sedative effect and in some countries is prescribed for insomnia when benzodiazepines are contraindicated...
otherwise as second choice metoclopramide
Metoclopramide
Metoclopramide is an antiemetic and gastroprokinetic agent. It is commonly used to treat nausea and vomiting, to facilitate gastric emptying in people with gastroparesis, and as a treatment for the gastric stasis often associated with migraine headaches.-Medical uses:Metoclopramide is commonly...
, or prochlorperazine
Prochlorperazine
Prochlorperazine is a dopamine receptor antagonist that belongs to the phenothiazine class of antipsychotic agents that are used for the antiemetic treatment of nausea and vertigo. It is also a highly-potent typical antipsychotic, 10-20x more potent than chlorpromazine...
. When all other treatments fail, doctors may consider trying a corticosteroid medication such as methylprednisolone. This medication can be given orally or intravenously. It should not be used before 10 weeks gestation because of a small risk that it could cause a cleft lip or palate in the fetus. Because of possible maternal complications, the medicine should not be used for longer than six weeks.
Thalidomide
ThalidomideThalidomide
Thalidomide was introduced as a sedative drug in the late 1950s that was typically used to cure morning sickness. In 1961, it was withdrawn due to teratogenicity and neuropathy. There is now a growing clinical interest in thalidomide, and it is introduced as an immunomodulatory agent used...
was originally developed and prescribed as a cure for morning sickness in West Germany
West Germany
West Germany is the common English, but not official, name for the Federal Republic of Germany or FRG in the period between its creation in May 1949 to German reunification on 3 October 1990....
, but its use was discontinued when it was found to cause birth defect
Congenital disorder
A congenital disorder, or congenital disease, is a condition existing at birth and often before birth, or that develops during the first month of life , regardless of causation...
s. The United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
Food and Drug Administration
Food and Drug Administration
The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...
never approved thalidomide for use as a cure for morning sickness.