Morning sickness is one of the most common symptoms of early pregnancy, affecting around 70-80% of pregnant women. It typically begins around 4-6 weeks of pregnancy and peaks around 9 weeks, though it can start as early as 2 weeks or last as late as 16-20 weeks for some women. Understanding when morning sickness is most likely to occur can help pregnant women know what to expect and find ways to manage their symptoms.
What is Morning Sickness?
Morning sickness is the feeling of nausea and vomiting that occurs during pregnancy. Despite its name, morning sickness can occur at any time of day, though it is often worst upon waking in the morning. The exact causes are unknown but are likely related to the hormonal changes of early pregnancy. Two key hormones, human chorionic gonadotropin (hCG) and estrogen, rise rapidly during the first trimester. These hormones are thought to slow digestion and relax muscles along the digestive tract, which can trigger nausea and vomiting.
While commonly called morning sickness, the medical term for pregnancy-related nausea and vomiting is nausea and vomiting of pregnancy (NVP). There are three classifications of NVP:
- Nausea alone
- Nausea with vomiting
- Hyperemesis gravidarum – severe, persistent nausea and vomiting requiring medical treatment
Up to 90% of pregnant women will experience some degree of NVP. For most it is mild and more of a nuisance than anything. But for some women it can be severe, leading to weight loss and dehydration.
When Does Morning Sickness Usually Start?
Morning sickness typically begins around 4-6 weeks of pregnancy. This is about 2 weeks after a missed menstrual period, right around the time when an at-home pregnancy test turns positive. Some women may start to feel queasiness as early as 2 weeks after conception. Others may not experience any symptoms until 8 weeks or later. According to one study, the breakdown is:
- Less than 1 week: 2%
- 1 week: 5%
- 2 weeks: 13%
- 3 weeks: 24%
- 4 weeks: 36%
- 5 weeks: 54%
- 6 weeks: 68%
As you can see, the 4-6 week range is when the majority of pregnant women begin noticing symptoms of morning sickness. The rising hCG and estrogen levels around this time are thought to trigger the nausea.
When Does Morning Sickness Peak?
For most women, morning sickness tends to worsen around weeks 8-10 of pregnancy and peaks around week 9. One study found the percentage of pregnant women experiencing nausea at different points was:
| Weeks Pregnant | Percentage with Nausea |
|---|---|
| 6 weeks | 68% |
| 8 weeks | 84% |
| 9 weeks (peak) | 88% |
| 10 weeks | 86% |
| 12 weeks | 80% |
| 16 weeks | 55% |
This corresponds with the time when hCG levels reach their highest point during pregnancy. The rapidly rising hormones seem to aggravate nausea for many women. Plus, around 9 weeks the placenta takes over hormone production, so levels fluctuate up and down, which can also increase nausea.
When Does Morning Sickness End?
While every woman is different, most find their morning sickness symptoms start to subside around weeks 14-16 of pregnancy. The peak of morning sickness at 9 weeks represents a turning point, after which nausea gradually decreases for many women. By week 16, around 55% of pregnant women still have nausea, down from 86% at week 10.
A few factors account for morning sickness subsiding around the start of the second trimester:
- Hormone levels plateau – hCG and estrogen stop rising rapidly
- The placenta takes over hormone production from the ovaries
- The uterus grows out of the pelvis, reducing pressure on internal organs
- The fetus’s nutritional needs increase, motivating the mother to eat
For some women, nausea and food aversions can linger for several more weeks or even the entire pregnancy. But most find relief by weeks 16-18 at the latest.
When to Seek Help for Morning Sickness
While morning sickness is common and usually not harmful, severe symptoms can result in dehydration, electrolyte imbalance, and weight loss. Hyperemesis gravidarum occurs in up to 2% of pregnancies and causes persistent vomiting along with:
- Weight loss of more than 5% of pre-pregnancy weight
- Dehydration and electrolyte imbalances
- Nutritional deficiencies
Signs it may be time to call your doctor about morning sickness include:
- Vomiting more than 3-4 times per day
- Inability to keep down any food or liquids
- Dark urine or inability to urinate
- Rapid weight loss
- Confusion, weakness, or fainting
Severe nausea and vomiting during pregnancy requires medical treatment, typically with IV fluids, anti-nausea medication, and vitamins. With proper management, most women can get relief and continue to have a healthy pregnancy.
Tips for Managing Morning Sickness
While morning sickness usually resolves on its own by the second trimester, there are some self-care tips that can help minimize symptoms:
- Eat small, frequent meals instead of large meals
- Avoid greasy, spicy, or overly sweet foods
- Eat bland, dry foods like crackers or plain toast
- Drink plenty of fluids, especially if vomiting – try sipping ginger ale, lemonade, or electrolyte drinks
- Get plenty of rest
- Consider complementary therapies like acupressure bands or ginger
- Use motion-sickness remedies like lemon essential oil or vitamin B6
Talk to your doctor about prescription anti-nausea medication if symptoms become severe. Getting nausea under control is important for both mom’s health and proper fetal development.
When to Expect Morning Sickness with Subsequent Pregnancies
If you dealt with morning sickness during your first pregnancy, you may wonder – will it be the same with future pregnancies? In general, patterns tend to repeat themselves. Women who had no morning sickness with their first are likely to have an easy time with subsequent pregnancies. And women who struggled with severe nausea and vomiting are prone to experiencing it again later on.
However, every pregnancy is different. Some women find morning sickness is worse with their second or third child. Others actually have an easier time. According to one study looking at patterns with multiple pregnancies:
- 27% of women had no change in severity
- 20% had worse symptoms
- 15% had less severe symptoms
Contributing factors like carrying multiples or having a girl versus boy can affect morning sickness as well. The only way to know for sure is to talk with your doctor and pay attention to patterns with your own pregnancies. Be sure to seek medical attention promptly if symptoms become severe.
Conclusion
Morning sickness is most common from weeks 6-10 of pregnancy, with a peak around week 9. Hormonal changes are thought to trigger nausea that starts as hCG rises around 4-6 weeks and peaks when hCG is highest. Most women find relief by weeks 14-16 as hormone levels plateau. Understanding the usual time frame can help pregnant women be prepared. But keep in mind every woman is different and the severity of morning sickness can vary from pregnancy to pregnancy. Talk to your doctor if nausea and vomiting become excessive or lead to other medical concerns.