Select a condition Absence seizures Acne ADHD Age-related macular degeneration AIDS Alzheimer's disease AMD Amebic dysentery Anal tears Angina, stable Angina, unstable Ankle sprain Anorexia Anxiety Appendicitis Arthritis Asthma in adults Asthma in children Athlete's foot Atrial fibrillation Attention deficit hyperactivity disorder (ADHD) Autism Back pain Bacterial vaginosis Bad breath Bedsores Bedwetting Bell's palsy Benign prostatic hyperplasia Bipolar disorder Bladder infection in women Blood pressure Breast cancer Breast pain Bronchiectasis Bronchiolitis Bronchitis Bulimia Bunions Burning mouth syndrome Burns and scalds Canker sores Cardiac arrest Carpal tunnel syndrome Cataracts Cellulitis and erysipelas Chickenpox Childbirth, heavy bleeding Childbirth, tear or cut Chlamydia Chronic bronchitis Chronic fatigue syndrome Chronic obstructive pulmonary disease Chronic prostatitis Chronic tension type headache Cold sores Colic in babies Colon and rectal cancer Colon and rectal cancer screening Colonic diverticular disease Common cold Conjunctivitis Constipation in adults Constipation in children COPD Crib death Deep vein thrombosis Dementia Depression in adults Depression in children Diabetes, type 1 Diabetes, type 2 Diarrhea in adults Diarrhea in children Diverticular disease Ear infection, middle ear Ear infection, outer ear Ear infection with discharge Ear infection with fluid Ear pain during air travel Ear wax Eczema Emphysema Endometriosis Enlarged prostate Epilepsy Episiotomy Erection problems Essential tremor Febrile seizures Fertility problems Fibroids Flu Gallstones Genital herpes Genital warts GERD GERD in children Glaucoma Gonorrhea Gout Group B streptococcus H. pylori infection Halitosis Hay fever Headache, chronic tension type Head lice Heart and circulation problems in diabetes Heart attack Heartburn Heart failure Heavy periods Heel pain Hemorrhoids Hepatitis B Hepatitis C Hernia Herpes, genital Herpes simplex eye infection High blood pressure High blood pressure in pregnancy High cholesterol HIV infection Hyperactivity IBS Incontinence in women Infection in newborn babies Infertility Influenza Insomnia in adults Irritable bowel syndrome Jaundice in newborn babies Jet lag Kidney infection Kidney stones Leg cramps Leg ulcers Lewy body dementia Lung cancer Lyme disease Macular degeneration Malaria prevention Manic depression Mastalgia Measles, mumps and rubella: prevention Melanoma Meniere's disease Meningococcal disease Menopause Migraine in adults Migraine in children MMR prevention Morning sickness Multiple sclerosis Nail infection, fungal Neck pain Nicotine addiction Non-Hodgkin's lymphoma Nosebleeds in children Obesity Obsessive-compulsive disorder OCD Oral thrush Osteoarthritis Osteoporosis Ovarian cancer Painful periods Pancreas cancer Panic attacks Parkinson's disease PCOS Pelvic inflammatory disease Perineal care Peripheral arterial disease Peripheral vascular disease Pneumonia Polycystic ovary syndrome Postpartum depression Postpartum hemorrhage Post-traumatic stress disorder Preeclampsia Pregnancy, nausea Premature birth Pressure sores Prostate cancer Prostatitis, chronic Psoriasis PTSD Raynaud's disease Rectal cancer screening Recurrent cystitis Reflux in children Rheumatoid arthritis Scabies Schizophrenia Seasonal allergy Shoulder pain Sickle cell anemia Sickle cell disease SIDS Sinusitis Skin cancer (melanoma) Skin cancer (squamous cell) Sleep apnea Sleep problems in children Slipped disk Smoking Sore throat Stomach ulcers Stress headache Stress incontinence Stroke, emergency care Stroke prevention Sudden infant death syndrome Swimmer's ear Tennis elbow Tension headache Testicular cancer Thrush (oral) Tic douloureux Tinnitus Tonsillitis Toxoplasmosis in pregnancy Trigeminal neuralgia Underactive thyroid Urinary tract infections in children Varicocele Varicose veins Vascular dementia Warts Whiplash Wisdom teeth, impacted Wrinkles Yeast infection, vagina

Select treatment area Bladder & Kidneys Blood Brain & nervous system Cancer Children's health Diabetes Digestive system Ear, nose & throat Eating & weight Eyes Fertility Heart and circulation Hormones Infections Lungs & breathing Men's health Mental health Mouth Muscles & bones Pregnancy & childbirth Sexual health Skin Sleep Staying healthy Travel health Women's health

During the first 12 weeks of pregnancy (called the first trimester), it's normal to have what is commonly called "morning sickness" -- feeling sick to the stomach and throwing up. This is unpleasant, but most often it will not hurt you or your baby. However, a few women do have serious nausea and vomiting during pregnancy and need medical treatment.

• It's normal to feel sick to your stomach and throw up during the first few months of pregnancy. Most pregnant women do.
• Nausea and vomiting won't usually harm you or your unborn baby.
• You may feel sick to your stomach at any time of the day, not just in the mornings.
• About 1 in 200 pregnant women have severe nausea and vomiting that can be dangerous to their health and their baby's health. Doctors call this condition hyperemesis gravidarum.
• Nausea and vomiting usually stop after about 12 weeks of pregnancy. But 1 in 10 pregnant women still have morning sickness after 20 weeks.

There are lots of myths about nausea and vomiting in early pregnancy. See how much you know by taking our quiz, Myths about nausea and vomiting in early pregnancy.

Feeling sick to your stomach and throwing up is often the first sign that you're pregnant. In fact, you may not have realized you were pregnant until you started to feel like this.

Almost all pregnant women have some nausea, although not everyone throws up. These symptoms usually begin around six weeks after the start of your last period.^{1 2}

Even if you throw up two or three times a day, usually you can keep some food down and won't lose weight during the first few months of pregnancy.

A survey of 1,000 women in the first half of their pregnancy gives us some idea of how you may feel during your pregnancy:¹

• About 6 in 10 pregnant women feel sick to the stomach every day
• About half of all pregnant women throw up, but only about 1 in 5 throw up every day
• Although nausea and vomiting in pregnancy is often called "morning sickness," only about 1 in 5 women say that their symptoms stop by noon
• Many women feel sick to the stomach and throw up at any time of the day, although they usually feel worse in the morning
• The earlier in your pregnancy that symptoms start (for example, around the fourth week), the more frequent they are likely to be.

Many women notice that certain things make them feel worse, or "trigger" their symptoms. Here are some common triggers:^{3 4}

• Smelling certain odors, especially coffee, perfumes, cigarette smoke and gasoline
• Cooking and eating certain foods, especially meats, fatty meals or spicy meals
• Becoming very tired
• Feeling anxious or worried
• Changing position quickly (for example, standing up fast).

We know very little about why some pregnant women get morning sickness and others don't. But it's nothing to worry about. In fact, women who do feel sick are less likely to have a miscarriage than women who don't feel sick.⁵

It's normal to feel sick to the stomach and throw up when you're pregnant. But it's not normal to feel so sick that you can't hold down any food or fluids for days on end.

Here's what we know about severe nausea and vomiting in pregnancy, which is called hyperemesis gravidarum.

• About 1 in 200 pregnant women have severe nausea and vomiting.⁶
• If you have hyperemesis gravidarum, your vomiting may be so bad that you lose weight, often about 10 pounds. To learn more, see What are the symptoms of normal and severe nausea and vomiting in early pregnancy?
• When you're pregnant, it's normal to feel very tired and emotional and to be worried about your unborn baby. You may feel even more emotional if you also have severe nausea and vomiting.
• You might be upset that you feel sick to your stomach, especially if you were looking forward to your pregnancy.
• Your symptoms may seem to clear up after your third month of pregnancy, but they might come back from time to time.
• You may be treated in the hospital to avoid becoming dehydrated and to make sure you get enough of the right nutrients. To learn more, see What happens in the hospital?
• Unborn babies are usually not harmed by severe nausea and vomiting. There's a small chance that you will lose weight or have a small baby, but if you receive treatment, this probably won't happen.
• If you feel very sick to your stomach and vomit during one pregnancy, you have about a 50 percent chance of feeling like this during another pregnancy.⁷

Doctors are not sure why most women feel sick to the stomach and throw up when they're pregnant. But some doctors think morning sickness may protect your baby from threats in the environment. Being pregnant may make you more sensitive to these dangers.⁴

For example, when you are near car or gas fumes, you may move away because the smell makes you feel queasy. This may keep poisons out of your body and away from your unborn baby.

Nausea and vomiting may go away when you're about three months pregnant because your baby has passed through important stages of development. Poisons are generally less harmful to your baby later in your pregnancy.

Here are some of the most popular theories that explain why pregnant women feel sick to the stomach and throw up.

• Many doctors think that the sudden rise of a hormone called human chorionic gonadotrophin (HCG) during early pregnancy makes women feel sick to the stomach.⁴ There seems to be no link, however, between how much HCG you have in your blood and how bad your nausea and vomiting will be. Still, you are more likely to feel sick to your stomach and throw up if you're expecting twins, when levels of this hormone rise higher than if you're expecting a single baby. You're also more likely to feel very sick to your stomach if you have a hydatidiform mole, also called molar pregnancy. To learn more, see Molar pregnancy.
• HCG looks a lot like another hormone (thyroid stimulating hormone or TSH) that tells the body to make more thyroid hormone. So HCG can also send a message to the body to make more thyroid hormone. It is possible that high levels of thyroid hormone are what causes the nausea and vomiting.
• Not getting enough of some vitamins and minerals, such as vitamin B-6, may cause nausea and vomiting.⁸

Doctors and researchers have many more ideas about what causes nausea and vomiting in early pregnancy. For more of their thoughts, see Other possible causes of nausea and vomiting in early pregnancy.

Doctors don't know why some women feel sick to the stomach and throw up during pregnancy and others feel fine. They also don't know why one pregnant woman has only mild nausea while another vomits several times a day for many months.

But there are certain factors that increase your chances of nausea and vomiting when you're pregnant. Doctors call these risk factors. To learn more, see Risk factors for nausea and vomiting in early pregnancy.

This information is for educational use only, and is not a substitute for prompt professional medical advice. Readers should always consult a physician or other professional for advice and treatment. ©BMJ Publishing Group Limited 2008. All rights reserved.