It mostly strikes in the first trimester (as early as the second week after conception) although some women (around 20 per cent) report feeling nausea and discomfort in the stomach, followed by an urge to vomit, into the second trimester or right up until the baby arrives.
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Why does it occur and is it normal?
Morning sickness in the third trimester is completely normal and, despite its name, can occur any time of day. It can be caused by a few factors. These include:
- The stomach and gastrointestinal muscles relaxing, which causes digestion to slow down and forces food back up the oesophagus
- The baby’s growing weight inside the uterus, which puts pressure on the stomach
- Fluctuations in hormones (although this mostly happens during the first trimester)
- Fluctuations in blood pressure (especially low blood pressure)
Eating foods that are hard to digest (e.g. oily, acidic or spicy foods) or large meals may also lead to nausea, vomiting and reflux in the later stages of pregnancy.
When should I seek extra medical advice?
Generally, nausea late in pregnancy is nothing to worry about. However, if it goes and comes back, it may be an indication of an underlying health condition, for example, pre-eclampsia - which is definitely a cause for concern.
Does advice differ depending on how many weeks pregnant you are?
At least 7 in 10 pregnant women (70 per cent) experience morning sickness in the first trimester (the first 12 weeks). It usually starts around the 4-6 week mark and is at its worst at about 9 weeks. For most, this resolves by the 12th-14th week, although in some it will go and come back around the 27th-28th week.
Regardless of what stage of your pregnancy you are, it’s always best to check with your doctor if you’re concerned about your symptoms.