Morning sickness, which involves nausea and vomiting, is one of the earliest and most common symptoms of pregnancy. For many women, morning sickness starts around 6 weeks of pregnancy, but it can begin as early as 4 weeks. There is a wide range in when vomiting starts during pregnancy, but most women will experience it by 9 weeks gestation.
What Causes Vomiting in Early Pregnancy?
The exact causes of morning sickness are not fully understood, but it is thought to be caused by the hormonal changes of early pregnancy. Two main hormones are linked to nausea and vomiting:
- Human chorionic gonadotropin (hCG) – Levels of this hormone rise rapidly in early pregnancy. It is responsible for maintaining the pregnancy.
- Estrogen – Estrogen levels also increase significantly after conception. This hormone stimulates the growth of the placenta.
Rising hCG and estrogen is believed to cause nausea and vomiting by:
- Slowing digestion
- Increasing smell and taste sensitivity
- Stimulating the parts of the brain that control nausea and vomiting
The rapid rise in hormones likely causes more severe nausea and vomiting in some women. Genetics and increased sensitivity to hormonal changes may also play a role.
When Does Vomiting Usually Start in Pregnancy?
Here is an overview of when vomiting often begins during the first trimester:
- 4 weeks pregnant – Some women start feeling nauseous this early. Vomiting is less common.
- 6 weeks pregnant – Most women start experiencing morning sickness around this time. Nausea is common and some vomiting may occur.
- 8-9 weeks pregnant – Morning sickness tends to peak at this time. Most women will experience nausea and vomiting.
- 10-12 weeks pregnant – Hormone levels start to even out. Nausea and vomiting typically improve.
While many women follow this pattern, there is a lot of variation in the timing and severity of nausea and vomiting during pregnancy:
- Some women feel nauseous before missing a period at 4 weeks.
- A number of women don’t experience vomiting until 8 or more weeks.
- Morning sickness ends by 14-16 weeks for most women.
- Up to 20% of pregnant women deal with nausea and vomiting after 20 weeks.
Percentage of Pregnant Women Experiencing Vomiting by Week
| Weeks Pregnant | Percentage Experiencing Vomiting |
|---|---|
| 4 weeks | 10% |
| 6 weeks | 25% |
| 8 weeks | 50% |
| 10 weeks | 60% |
| 12 weeks | 40% |
This table shows the rapid increase in vomiting that occurs between 4 and 10 weeks of pregnancy. More than half of pregnant women experience vomiting by 8 weeks gestation.
How Long Does Morning Sickness Last?
For most women, nausea and vomiting starts to improve significantly by weeks 14-16 of pregnancy. But the duration of morning sickness varies:
- Mild morning sickness – May end by week 12
- Moderate morning sickness – Lasts until week 16
- Severe morning sickness – Can last until delivery
If vomiting and nausea are not improving by weeks 14-15, be sure to talk to your doctor. You may need medication or IV fluids to treat severe morning sickness.
Average Duration of Morning Sickness
| Severity | Weeks Experiencing Vomiting |
|---|---|
| Mild | 4-12 weeks |
| Moderate | 4-16 weeks |
| Severe | Potentially entire pregnancy |
This table indicates most women have vomiting for 8 or more weeks. But severe cases can last 20 weeks or longer.
When to See Your Doctor
Talk to your doctor right away if you have any of the following:
- Vomiting and nausea that prevents eating/drinking for 24 hours
- Losing more than 2-3 pounds due to vomiting
- Dark urine or not urinating for 8 hours
- Symptoms that persist past week 16
Severe vomiting and nausea requires medical treatment to prevent dehydration and electrolyte imbalances. There are prescription medications and IV fluids that can provide relief.
Key Points
- Morning sickness starts around week 6 for most women, but it can begin as early as 4 weeks.
- 60% of pregnant women experience vomiting by 10 weeks gestation.
- Moderate morning sickness typically lasts until weeks 14-16.
- Contact your doctor if vomiting prevents eating/drinking or lasts beyond 16 weeks.
Coping with Morning Sickness
While it’s common, morning sickness can significantly impact your quality of life in early pregnancy. Here are some tips to minimize nausea and vomiting:
- Eat small, frequent meals instead of large ones
- Avoid having an empty stomach by eating snacks between meals
- Stay hydrated by sipping on cold, clear fluids like water or ginger ale
- Get plenty of rest and sleep
- Avoid spicy, greasy, and overly sweet foods
- Increase protein intake from foods like eggs, yogurt and lean meat
- Try ginger, which may reduce nausea
- Use sea bands, which apply pressure to nausea-relieving acupressure points
- Consider using B-6 and doxylamine (Unisom) supplements, which are safe in pregnancy
Making lifestyle changes and using remedies like ginger and B-6 can help minimize vomiting episodes. But don’t hesitate to talk to your doctor if your morning sickness is not improving or preventing you from staying hydrated and nourished.
Conclusion
Nausea and vomiting affects over 60% of pregnant women. Hormone changes are believed to cause morning sickness, which typically peaks between 8 and 10 weeks. For most women, symptoms start improving by weeks 14-16. But severe cases can last the entire pregnancy.
Vomiting and nausea early in pregnancy is normal, but be sure to reach out to your doctor if you can’t keep food or fluids down for over 24 hours. There are medications and interventions that can provide relief from severe morning sickness and prevent dehydration.