What causes morning sickness?

Nausea can kick in by the time a woman is 6 weeks pregnant, and although traditionally known as “morning sickness”, this debilitating condition is not governed by the clock and can actually hit you at any time day or night. It is a very unpredictable condition; some women sail through their pregnancies without even feeling sick once, whereas others can be truly miserable and extremely unwell, even requiring medical treatment.

Scientific research has led to the assumption that sickness is triggered by HCG, a hormone which increases rapidly in early pregnancy. This levels of this hormone plateau by the end of the first trimester, which is also when most women find their nausea starting to ease. It has been noted that extreme sickness is more common in twin pregnancies where the HCG level will be higher than in singleton pregnancies. Increasing levels of sickness can also be more common in trophoblastic disease such as molar pregnancy, a rare condition where abnormal cells develop in the womb instead of a healthy embryo and placenta.

What is hyperemesis?

Hyperemesis Gravidarum (HG) is a very severe form of sickness in pregnancy that affects up to 2% of women. These patients suffer from persistent nausea and vomiting, weight loss, dehydration, and electrolyte imbalances to the point that they often have to be admitted to hospital. HG can have a significant impact on quality of life and can lead to serious complications if not treated.

Can you take any medication for sickness in pregnancy?

There are a number of medications which are safe to take in pregnancy and these can prove very effective for patients who are struggling with nausea and vomiting. It is worth speaking to your GP or midwife if you feel very unwell or are finding it difficult to hold down the usual amount of food and drink. These medicines are known as antiemetics and include drugs such as cyclizine, prochlorperazine and ondansetron. You may find that the first medicine may not be effective; if so then return to your GP to try another. Mild to moderate nausea and vomiting in pregnancy are often coped with without any intervention if normal day to day routines are still able to be carried out.

Some women prefer to try natural remedies including ginger. An article published in 2016 in the scientific journal Integrative Medicine Insights quoted 13 studies where ginger was found more effective than a placebo in improving nausea in pregnancy. Bland frequent snacks can be preferable to large hot meals, and it may be advisable to take vitamin supplements to ensure you do not become deficient in any vital vitamins or minerals. Vitamin B6 has also been shown in scientific studies to be particularly helpful in lowering vomiting when compared to a placebo.

Severe sickness in pregnancy

Severe sickness and HG can be very isolating. In addition to struggling with physical symptoms, HG is associated with increased risks of anxiety and depression as patients cannot continue with their usual routine or life due to how ill they feel. The charity Pregnancy Sickness Support offers advice and details of where to get help at https://www.pregnancysicknesssupport.org.uk/index.php?page=home. There is also a good level of helpful information available via the HER Foundation at https://www.hyperemesis.org.  It is important to note that, while HG is a serious condition, it is usually treatable. With proper treatment and support, most women with HG can go on to have healthy pregnancies and deliveries and even choose to have subsequent babies.

Why do some women get hyperemesis gravidarum and not others?

There is a lot of debate about why some women are so badly affected by sickness in pregnancy, and others are not. Whilst most clinicians agree that rising hormones are to blame for increasing symptoms, it is not well understood why some patients suffer a lot more than others. Genetic factors may be influential as HG can run in families. A study implemented by the University of California in 2022 found links to HG in variations of the GDF15 gene https://keck.usc.edu/researchers-identify-gene-mutations-linked-to-pregnancy-sickness/#:~:text=HG%20can%20be%20passed%20down,suicidal%20ideation%20and%20even%20death.

Other recent research has looked at identifying biomarkers that can help in predicting HG. A study published in the Journal of Clinical Endocrinology and Metabolism found that women with HG had higher levels of the hormone cortisol and lower levels of the hormone progesterone compared to women without HG. Another study published in the American Journal of Obstetrics and Gynecology found that women with HG had higher levels of the hormone leptin and lower levels of the hormone ghrelin. 

What is the difference between hyperemesis gravidarum and morning sickness?

If you are feeling sick and regularly vomiting during your pregnancy you may wonder if this is normal or if you are suffering from hyperemesis gravidarum. The key advice is to be led by your symptoms. If you are losing weight and feel extremely unwell or if you are vomiting numerous times a day to the point that you do not feel you are holding down enough fluid or food, and you cannot carry out your normal day to day activities, then it is important to seek medical help. 

Why does morning sickness get better after 3 months?

 Usually, pregnancy symptoms such as nausea and vomiting improve considerably after 3 months, and often cease completely. As mentioned above, levels of HCG hormone plateau at the end of the first trimester of pregnancy. Around that time, the placenta takes over vital tasks such as hormone production and nutrition of the foetus (in the early weeks the embryo is fed by a yolk sac.) Fatigue and other troublesome symptoms also often resolve by the second trimester.