For some, it's a minor inconvenience that calms down as their pregnancy progresses, but for others, pregnancy sickness is a serious condition that can affect many other areas of their health.
Whether you're suffering from morning sickness, being sick all day or just constantly nauseous and after some answers, here's what you need to know.
How do I know if I've got morning sickness?
When does morning sickness start?
Why does morning sickness happen?
Can morning sickness harm the baby?
Is it dangerous to let morning sickness go on untreated?
What treatment is there for morning sickness?
Should I be given medication for morning sickness?
If you have morning sickness once, will you have it the next time, too?
It happened to me: 'I had morning sickness morning, noon and night!'
How do I know if I've got morning sickness?This is an easy one - you can't stop throwing up!
Pregnant women can suffer from nausea morning, noon or night. Some women only experience mild morning sickness symptoms, where certain foods and smells make them feel queasy, but not physically sick, but others just can't stop vomiting. Often eating or drinking makes the sickness worse, leading to sudden weight loss.
In more extreme cases, some sufferers also get ptyalism, where they can't swallow their own saliva without vomiting. Other symptoms include dark-yellow urine, dry mouth and lips, urinating less than usual and feeling tired, sad or anxious. Severe morning or pregnancy sickness is known as hyperemesis gravidarum.
When does morning sickness start?Morning sickness usually occurs in the early stages of pregnancy - there's no hard and fast rule, but it usually comes on within the first 12 weeks after conception.
And how long does morning sickness last? It varies from woman to woman, but you'll probably find it clears up between week 16 and week 20 of your pregnancy. Having said this, some women, particularly those with hyperemesis gravidarum, may experience pregnancy sickness to term.
Why does morning sickness happen?The exact cause of morning sickness remains unknown, although many doctors believe it may be due to rapidly rising levels of hCG, the hormone secreted by the foetus, during the early stages of pregnancy. Normal morning sickness is caused by a slower rise of this.
Your risk factor for morning sickness can be affected by a family history of nausea and vomiting in pregnancy, a history of motion sickness, a history of nausea while using contraceptives that contain oestrogen, obesity, stress, or if it's your first pregnancy or a multiple pregnancy.
Can morning sickness harm the baby?In severe cases, the baby of a mother who has suffered from extreme morning sickness can be born prematurely or with a lower-than-average birth weight, but this is very rare.
Most mothers with morning sickness go on to have happy, healthy pregancies - your baby should still receive the correct amount of nutrients, even if you're vomiting every day, and there's no evidence that 'normal' pregnancy sickness has a negative impact on your baby in any way.
Is it dangerous to let morning sickness go on untreated?If you're suffering with hyperemesis gravidarum, and can't keep any food or water down, it's very important that you seek help from your doctor or midwife, as if left untreated, morning sickness during pregnancy can cause severe dehydration - which in serious cases can be life-threatening.
Thankfully, many women find that their morning sickness eases by their 2nd trimester.
What treatment is there for morning sickness?There are many morning sickness cures and remedies on the market, but many experts suggest trying natural remedies before reaching for other medicine.
The NHS recommends getting plenty of rest, drinking plenty of fluids, eating small, regular meals, and wearing comfortable clothes with elasticated waistbands where possible. Eating foods containing ginger and having acupressure are two other remedies that are often suggested.
Should I be given medication for morning sickness?If your nausea or vomiting is very extreme, and doesn't improve after you make the suggested changes to your lifestyle, your GP may recommend a short-term course of an anti-sickness medicine that is safe to use in pregnancy.
Some doctors won't prescribe anti-nausea drugs such as Zofran, as there's a lack of research into the long-term effects on the baby, though many believe there are none. If your GP prescribes anti-sickness drugs (eg: Stemetil, Zofran, or Maxallon), they should explain the risks involved in full.
If you have morning sickness once, will you have it the next time, too?Your risk factor for morning sickness is increased if you experienced pregnancy sickness with previous children, but it's not a certain thing.
Many women go on to have healthy further pregnancies with minimal sickness, even after really suffering the first time round.
It happened to me: 'I had morning sickness morning, noon and night!''When I was pregnant with my first child Lucy, I had morning sickness but nothing as bad as when I was pregnant with my second. That time, I felt terrible from the moment I woke up in the morning until the moment I went to sleep. It felt like the worst hangover ever and when I actually threw up, it was a relief.
Eating seemed to help and the first 12 weeks, I ate so much, I put on a stone and a half. I couldn't face certain foods like cooked meat but other foods I couldn't get enough of, like cereal with milk. Everyone kept telling me to try ginger but that made me feel sick too.
My sense of smell went through the roof. I couldn't bear the smell of anything, especially food cooking and wine. I had a disgusting taste in my mouth the whole time and my skin looked grey.
I went to bed at 6.30 some evenings and tried to sleep just to get away from the nausea, leaving my husband to look after Lucy. I went for lots of walks too as fresh air helped a bit.
Luckily, I started to feel a bit better when I was about 14 weeks pregnant. I don't know what I'd have done if it had lasted longer than that. Morning sickness is different for everyone - you've just got to work out what makes you feel better. Remember, it will stop soon and it is worth it in the end.'
Ali Jones, mum of two from South London
Tell us about your experiences of morning or pregnancy sickness in the comment box below.