23 Aug Feeling sick late in pregnancy? Nausea and Vomiting in the Third Trimester

Nausea and vomiting are often associated with early pregnancy, but some women find symptoms continue — or unexpectedly return — later on. Professor Steve Robson explains why it can happen, what may help, and when to call your doctor or midwife.

Why nausea can happen later in pregnancy

Most women will experience nausea, and possibly vomiting, in early pregnancy. While nausea and vomiting of pregnancy, often still referred to as “morning sickness”, is common and can be distressing, the more severe condition known as hyperemesis gravidarum is fortunately less common.

For the unlucky few who suffer unremitting nausea and vomiting through to the latter stages of pregnancy, the condition can be exhausting and debilitating. And then there are some women who have a complete recovery, assume they are in the clear, and then find the problems return towards the end of pregnancy.

As the uterus increases in size, the other abdominal organs — the bowel in particular — are compressed in the upper part of the abdomen, against the diaphragm.

The hormones of pregnancy also have some important effects. These hormones act to relax the valve, or sphincter, that normally holds the junction between the oesophagus, or gullet, and stomach closed.

At the same time, the movement of food onward from the stomach into the small bowel can be very slow, a condition known as gastroparesis.

This means there can be a lot of food in the stomach, which is then pressed from below by the growing uterus. Due to the laxity of the sphincter, the food can flow back upwards, and sometimes out. This can cause painful heartburn, nausea and, sometimes, vomiting.

What may help ease symptoms

Eating smaller meals, avoiding too much fluid with meals, taking pregnancy-safe antacids, and not eating too close to bedtime can help. Some women also sleep with their head elevated to help reduce reflux.

In more severe cases, when these measures do not provide relief, doctors sometimes prescribe medication that reduces acidity in the stomach, or helps the stomach empty more effectively. The good news is that these symptoms usually resolve once the baby is born.

Other causes of nausea and vomiting in late pregnancy

There are some other important conditions that can cause nausea and vomiting in late pregnancy, so if you are in any doubt about what is causing it, contact your doctor or midwife.

Food poisoning, for example from salmonella or E. coli, can cause a sudden onset of vomiting, often with diarrhoea as well.

Similarly, contagious episodes of gastroenteritis, such as those caused by norovirus, can also make pregnant women very unwell.

Vomiting and diarrhoea can last for several days and may lead to dehydration. This can pose risks for both mother and baby. For these reasons, it is important to be conscious of food safety and, where possible, avoid contact with people who have gastroenteritis.

When to seek medical advice quickly

Some important complications of pregnancy can sometimes cause upper abdominal pain, nausea and vomiting. Fortunately, they are rare, but women should always alert their doctor or midwife if symptoms feel unusual, severe, or are associated with other concerns.

Pre-eclampsia most commonly occurs in the second half of pregnancy and can cause high blood pressure and other symptoms. Warning signs can include a severe headache, vision changes, sudden swelling of the face, hands or feet, severe pain below the ribs or in the upper abdomen, nausea, vomiting, or feeling generally very unwell.

Another very rare condition is acute fatty liver of pregnancy. It can be difficult to diagnose because the early signs may be vague, but it can become serious and needs urgent medical care.

Trust your instincts

In summary, women who have nausea and vomiting in the third trimester will often feel better with simple measures.

However, if the condition does not respond, becomes severe, comes on suddenly, or is associated with pain, diarrhoea, headache, visual changes, swelling, dehydration, reduced baby movements, or simply feeling very unwell, contact your doctor, midwife or maternity hospital straight away.

It is always better to check.

Steve is a Professor of Obstetrics and Gynaecology at the Australian National University Medical School with special training and expertise in reproductive medicine, genetics, and pelvic surgery. He has authored hundreds of articles, papers, and textbooks – both in medicine and economics.

Editor’s note: This article was first published in 2014 and has been lightly reviewed and updated for clarity and current reader guidance. The author’s original wording has been retained as much as possible.