Nausea and vomiting of pregnancy commonly occurs between 5 and 18 weeks of pregnancy. Between 50 and 90 percent of women with normal pregnancies have some degree of nausea, with or without vomiting. The severity of these symptoms can vary and can last for various periods of time.
“Morning sickness” is the term often used to describe mild nausea and vomiting that occurs due to pregnancy (and not due to other illness), while “hyperemesis gravidarum” is the term used to describe a more severe condition. Hyperemesis may cause you to vomit multiple times throughout the day, lose weight, be unable to consume food and liquids, and typically requires evaluation in the hospital and treatment with medication(s).
MORNING SICKNESS VERSUS HYPEREMESIS
Morning sickness — Nausea and vomiting often develop by five to six weeks of pregnancy. The symptoms are usually worst around nine weeks and typically improve by 16 to 18 weeks of pregnancy. However, symptoms continue into the third trimester in 15 to 20 percent of women and until delivery in 5 percent of women. Although mild pregnancy-related nausea and vomiting is often called “morning sickness,” you may feel sick at any time of day, and many women (80 percent) feel sick throughout the day or even at night. Of note, women with mild nausea and vomiting during pregnancy experience fewer miscarriages and stillbirths than women without these symptoms.
Hyperemesis gravidarum — Hyperemesis gravidarum is the term used to describe more severe nausea and vomiting during pregnancy. Women with hyperemesis often vomit every day and may lose more than 5 percent of their pre-pregnancy body weight. In most cases, women with hyperemesis gravidarum become dehydrated and may develop vitamin and other nutrient deficiencies.
CAUSES OF NAUSEA AND VOMITING IN PREGNANCY
The cause of pregnancy-related nausea and vomiting is not clear. Several theories have been proposed, although none have been definitively proven. Increased hormone levels, slowed movement of the stomach contents, a genetic predisposition, and psychological factors are among the more common theories.
Some women are more likely to develop nausea and vomiting of pregnancy, including women who:
- Developed these symptoms in a previous pregnancy
- Experience nausea and vomiting while taking estrogen (for example, in birth control pills) or have menstrual migraines
- Experience motion sickness
- Have family members (especially sisters or mothers) who had these symptoms in pregnancy
- Have a history of gastrointestinal problems (ie, reflux, ulcers)
- Have twins, triplets, or other multiples
- Have a molar pregnancy (a type of abnormal placenta and pregnancy)
PROGNOSIS AND OUTCOMES
Most women with pregnancy-related nausea and vomiting recover completely without any complications. Women with mild to moderate vomiting often gain less weight during early pregnancy. This is rarely a concern for the baby unless the mother was very underweight before pregnancy (at least 10 percent under the ideal body weight). Most weight gain in pregnancy occurs in the last half of pregnancy, after pregnancy-associated nausea and vomiting has resolved.
Normal weight gain during pregnancy depends upon your pre-pregnancy height and weight. For women of normal weight (body mass index 18.5 to 24.9 kilogram/meter2), the recommended weight gain is between 11.5 to 16.0 kilograms for a singleton pregnancy.
Ginger – Ginger     may help to relieve nausea and vomiting in some women. Several studies have shown ginger to be more effective than placebo to reduce symptoms and frequency of nausea and vomiting. However, further studies are needed to confirm that powdered ginger is safe and effective.
The main substances that can be found in the composition of ginger root (the used portion), to which it owes its flavor, fragance and medicinal properties are:
Acid: linolenic, linoleic acid, ascorbic acid, aspartic acid, capric, caprylic, gadoleic glutamínico, myristic, oleic, oxalic.
Gingerol (ginger typical substance, structurally related to capsaicin and piperine).
Shogaol (only dried ginger probably occurs by modifying the effect of gingerol by dehydration).
Essential oils: citral, citronellal, limonene, camphene, beta-bisolobeno, beta-caryophyllene, beta-Bisabolol, alpha-farnesene cadineno alpha, alpha-cadinol. beta-phellandrene, beta-pinene, beta-sesquifelandreno, gamma-eudesmol.
Amino acids: arginine, asparagine, histidine, isoleucine, leucine, lysine, methionine, niacin, threonine, tryptophan, tyrosine, valine.
Minerals: aluminum, boron, chromium, cobalt, manganese, phosphorus, silicon, zinc
Digestive system: effects on vomiting, nausea appear to be related to its ability colagoga, stimulates the bile production and enzyme in the pancreas wich promoted the digestion.
- Comparison of ginger with vitamin B6 in relieving nausea and vomiting during pregnancy.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4649576/?report=printable
- Effect of Ginger on Relieving Nausea and Vomiting in Pregnancy: A Randomized, Placebo-Controlled Trial. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4228518/
- Effects of Ginger for Nausea and Vomiting in Early Pregnancy: A Meta-Analysis. https://www.jabfm.org/content/27/1/115.long
- Nausea and vomiting in early pregnancy. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3959188/
- The Effectiveness of Ginger in the Prevention of Nausea and Vomiting during Pregnancy and Chemotherapy. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4818021/
- A comparison between the effects of ginger, pyridoxine (vitamin B6) and placebo for the treatment of the first trimester nausea and vomiting of pregnancy (NVP) https://www.tandfonline.com/doi/abs/10.1080/14767058.2017.1344965?journalCode=ijmf20
- Vitamin B6 supplementation during pregnancy. WHO recommendations. https://www.who.int/elena/titles/vitaminb6-pregnancy/en/
- Vitamin B6 is effective therapy for nausea and vomiting of pregnancy: a randomized, double-blind placebo-controlled study. https://www.ncbi.nlm.nih.gov/pubmed/2047064