Morning Sickness & Miscarriage: How Much Does Nausea Lower Your Risk?

For most women, the first trimester is brutal. About a week or two after you find out you’re pregnant (two lines!), you start to feel exhausted, queasy, and like you might throw up at any moment.

You are not alone. Somewhere between 70-80% of pregnant women experience nausea during their first trimester. About half of women also experience vomiting.

Nausea tends to worsen with each subsequent pregnancy, and become more likely to persist into the second trimester. Your race and ethnic background also matter: White women are more prone to nausea than Black and Asian women, and Black women are more likely to have nausea that starts after the first trimester.

While morning sickness is awful, it does come with a significant silver lining: Nausea tends to signals a healthy pregnancy. Women with nausea have a much lower risk of miscarrying and–as is less widely known–a lower chance of preterm labor.

Morning Sickness and Risk of Miscarriage

For those experiencing nausea, the risk of miscarriage is not just a tiny bit lower, but a huge whopping amount lower than that of women with no nausea.

Woman with nausea have only a third of the chances of a miscarriage as other women. The effect is even stronger among women of “advanced maternal age”–that is, over 35: They have only about a fifth the odds of a miscarriage as other women over 35 with no nausea.

Despite these large effects, if you do not have any nausea, do not panic. A lack of morning sickness does not necessarily imply an impending miscarriage. A lucky 20-30% of pregnant women never experience any morning sickness but give birth to perfectly healthy babies.

Timing also matters: Before 7 weeks, a lack of nausea does not predict miscarriage risk.

Name Calling: Nausea and Vomiting of the Pregnancy (NVP) Versus Morning Sickness

Before we dig into the details, let’s get our terminology straight: Although nausea and vomiting during pregnancy are often referred to as “morning sickness”, most medical professionals prefer the term nausea and vomiting of the pregnancy (NVP). “Morning” sickness, they feel, is misleading.

As many first-time mums-to-be discover to their dismay, nausea often lasts all day long, not just in the morning, . In fact, in one study, less than 2% of women with “morning sickness” had nausea and vomiting only in the morning. Other studies have put the percentage of morning-only suffers at 14%.

The Onset of NVP and Miscarriage Risk

On average, women start to experience NVP 39-40 days after their last menstrual period, around the middle of the 5th week of pregnancy (counting from a woman’s last menstrual period), Symptoms typically begin to ease by around 12 weeks and usually disappear completely by 20 weeks.

That said, 39 days is only the average day of symptom onset. For an unlucky 10% of women, NVP begins much earlier, before they even miss their period. For the 70-80% women who will experience any morning sickness, though, that all day queasy, on-a-winding-road-with-a-bad-hangover feeling will have started by the end of your 8th week of pregnancy, or 7 weeks after conception.

So it’s only in 9th week of pregnancy that a lack of morning sickness predicts higher chances of a miscarriage, according to a prospective study that tracked symptoms of 2407 pregnant women from early in their first trimester.

Line chart shows chances of miscarriage peak in week 8 among those without nausea and vomiting, and remain higher until 13 weeks.

When a women’s nausea begins does not matter. Women who had nausea starting at 4 weeks or at 7 weeks have about the same low chances of a miscarriage.  Similarly, the end of nausea does not appear to make much of a difference. By 12 weeks, the risk of women without nausea drops back down to that of women with nausea.

What Exactly Is Morning Sickness and Why Does It Predict Miscarriage?

So we know that NVP is strongly related to the chances of a healthy, successful pregnancy. But why?

NVP is one of pregnancy’s great mysteries. We don’t know why it occurs. We don’t even know what hormones or other biological changes causes NVP. And we don’t know whether NVP serves a a specific adaptive purpose, as some evolutionary theorists have proposed, or whether it is just an unpleasant side effect of hormonal shifts during early pregnancy.

Rapid rises in hormones like estrogen, progesterone, and human chorionic gonadotropin (HCG) are the prime suspects. So far, though, the evidence for their role is only circumstantial.

Consider HCG, the hormone with the most evidence for a role in NVP. HCG levels in a woman’s blood rises rapidly during the early weeks of pregnancy, doubling every 2 to 3 days. Its concentration peaks sometime between 8-10 weeks of pregnancy.

HCG’s rise corresponds when NVP symptoms are usually at their worst. Conditions which cause high HCG levels like Down’s Syndrome, molar pregnancies, and twin pregnancies are often linked with severe NVP.

That said, HCG levels do not reliably distinguish women with and without NVP, and no one understands why, at a biological level, HCG would induce nausea.

Another potential suspect is pregnant women’s bloodhound-like sense of smell. In a small study of 9 women who had congenital anosmia–they were born with without the ability to smell–only 1 of the 9 suffered from NVP during pregnancy, a rate substantially lower than the usual 4 out 5.

Despite our poor understanding what causes nausea biologically, few researchers believe that a lack of symptoms causes miscarriage.

Why not? For one, treating NVP does not lead to worse pregnancy outcomes. If anything, the opposite is true: Women who take anti-nausea medications have better outcomes, on average, than women who do not take anti-nausea medications–not because treatment itself improves outcomes, but because severe NVP severe usually indicates a healthy placenta.

The Bottom Line

For everyone discretely ducking out of meetings to quietly vomit in the ladies room, there is light at the end of the tunnel. And knowing that your sickness likely means that your pregnancy may provide some comfort. I always clung to that fact as I was clinging to the toilet bowl after dinner.

But please do not think I am trying to minimize the dreadfulness of nearly non-stop nausea.

Nausea and vomiting are more than a simple inconvenience. Women with NVP, even those with so-called “mild” NVP accompanied by little or no vomiting, commonly report decreased productivity at work, taking sick time, strained relationships with their partners, and heightened anxiety and depression.

For around 1 in 100 pregnant women, NVP is life-threatening. Women with especially severe NVP, a condition known as hyperemesis gravidarum, suffer from such severe nausea that they cannot keep food or water down, and require hospitalization. In the U.S. each year, around 50,000 women are hospitalized for severe NVP.

If you are vomiting several times a day or unable to keep fluids down, seek medical help right away. Early treatment may help prevent NVP from becoming dangerously severe.

Published by

Amy Kiefer

As a former research scientist and proud mama of three little munchkins, I love digging into the research on all things baby-related and sharing it with my readers.

31 thoughts on “Morning Sickness & Miscarriage: How Much Does Nausea Lower Your Risk?”

  1. Thanks Amy for this post. Somehow, I find it comforting to read some real scientific facts about so-called “morning sickness”, even though the main conclusion is that scientists don’t understand why it’s there and don’t know how to make it stop. In my experience NVP per se is bad, but what makes it even worse is the lack of consideration you get from healthcare providers and the society. From “It’s all in your head” to “You’re so lucky to be pregnant, why are you complaining?” and “You can’t get any medicine but you should try homeopathy”, most reactions I got to my severe NVP during my first pregnancy didn’t help much… I’m now 3 months into my second pregnancy and, surprisingly enough, NVP is less severe now than it was the first time (and no, it’s not a sign of impending miscarriage, we’ve just had a ultrasound, everything’s fine). I’d love to understand why it is so, from a scientific perspective: how can hormon releases be so different from one pregnancy to the next? Do you have any readings to suggest? Thanks!!

    1. Hi Clara!

      I agree–unsympathetic reactions to morning sickness are infuriating. Even recently, some doctors have subscribed to the idea that psychological problems lead to hyperemesis gravidarum, an incredibly condescending and retrogressive view. I have no doubt that women would receive more empathy and better treatments if men suffered from morning sickness too.

      As for why you’d have less morning sickness the second time around, I don’t think there are any truly good answers. Some things that might be at play: Older women tend to have less severe morning sickness. Women who have very severe morning sickness, with a diagnosis of hyperemesis gravidarum (HG), are more likely to be carrying girls (about 60% of the time). Oddly enough, fetal sex does not correspond to severity of NVP symptoms for women without HG.

      You may want to read some of Marlena Schoenberg Fejzo’s publications. She’s a researcher who studies the genetics of HG, and she suffered from extremely severe HG during her second pregnancy. If you needed rehydration for severe morning sickness during your first pregnancy, you might also be eligible for her ongoing study on the severity of morning sickness.

      1. Thanks Amy for your reply! I was lucky enough to escape HG on my first pregnancy. And even luckier this time: now in my second trimester, nausea almost disappeared, what a relief 🙂

  2. I’ve had 5 miscarriages, and was sick as a dog with all of them. In my case, at least, morning sickness did not equal healthy pregnancy. 🙁

    1. I am so sorry to hear about your miscarriages. And you provide a good reminder–none of these associations are 100%. Some people with morning sickness will go on to miscarry, and some without will go on to have perfect normal healthy pregnancies.

      Have you talked with someone who specializes in recurrent losses about what might be going on?

  3. It might be reassuring and comforting for pregnant women who have MS. However, for pregnant women with no or very little nausea like me, reading everywhere that MS is a sign of an healthy pregnancy is very stressing.. I am spending my whole first trimester worrying. I am almost 11 weeks and hope everything is going well and cannot wait to pass the 14-week mark.

    1. I can see how not experiencing nausea might be scary too. At 11 weeks, though, your chances of a miscarriage are much lower than earlier, so it’s very likely you just lucked out when it came to morning sickness.

      Congrats on your pregnancy–and I hope everything continues to go smoothly.

  4. Hi, I’m not sure I understand your odds comparison, would you be able to explain a bit more? The y axis scale of your graph – odds of miscarrying – is ‘odds’ a measurement? I’m not sure I understand the unit being measured. So in other words – a 0.1 chance of miscarrying, the highest one in the graph, does that mean a 1 in 9 chance? Or is this way too simplistic. This may be my lack of stats knowledge showing Thanks!

  5. Might sound like silly questions but what if your man is experiencing “morning sickness” too? I read your miscarriage pages and data. Is there any data for when he gets sick with you or is it an entirely different subject that has no grounding on miscarriage statistics?

  6. Hi. Thanks for your post–I like your stuff. I’m a researcher (epigenetics) and acupuncturist, and I just wanted to push back a bit on your statement that “acupuncture, though popular, does not appear to be effective.” I know this to be untrue personally and clinically, and I do not want folks who are suffering and read this to dismiss what is a gentle, non-pharmaceutical and effective solution.

    Now don’t get me wrong–acupuncture does not *cure* NVP. Acupuncture doesn’t work against nature and I am one of those scientists who believes that we are sick during pregnancy because this sickness played a role evolutionarily, ie, those who got sick were less likely to eat toxic foods and thus fitter than others. But I have never met a pregnant woman with NVP (and I have treated dozens of them) who did not get relief from acupuncture, either for a day, and sometimes up to five days.

    Ironically, I don’t know the research on this. You probably do, though I thought it was interesting that your dismissal of acupuncture was without evidence. I’m sure there are articles that say acupuncture doesn’t work for NVP because there is tons of sloppy research on acupuncture by non-practitioners. This isn’t a bias of mine, truly, but I am qualified to make that statement as a scientist and practitioner.

    I will tell you, when I am treating something tricky I live and breathe the evidence–all I do is read paper after paper. Parkinson’s, neuralgia, this is some tricky stuff to treat. There are lots of opinions. Reading the data matters. But with NVP, I haven’t even done a single search. There’s no need to. It’s the most simple treatment there is. Depending on severity it can be done in 5 minutes with 4 needles. And it works.

    You don’t seem to be someone who would make a comment like the aforementioned without evidence, so even though you didn’t cite it, I trust that you made an informed comment and were not providing readers with your opinion. But please, this is my plea to women who need help with NVP and who are reading your blog (and thus interested in evidence): regardless of what researcher says acupuncture doesn’t work for NVP, talk to people. Or better yet, try it yourself. Research does not and cannot (and I am a researcher here) fully capture the lived experience. Be open to helping yourself naturally.

    Two stories for those who want some anecdotal data:

    (1) I treated a woman, pregnant with twins, with the most severe NVP I’ve ever seen. She hadn’t tried acupuncture before pregnancy so didn’t think of it for her NVP. She found me at 9 weeks, at which time she had lost significant weight. I treated her twice a week until 14 weeks. On treatment days, she feels like normal–she eats whatever she wants, doesn’t vomit, and doesn’t have a problem. On the day after treatment she starts to feel mildly nauseated, but can still eat normally and doesn’t vomit. Two days after treatment she is very nauseated. She would come back the 3-4 days after treatment. By the way, she drove 75 minutes to come for treatment. After getting treated she gained her weight back and continued to gain.

    (2) I treat myself! I am pregnant (that’s how I got to this site!) and suffer from NVP. When I start to feel sick, I treat myself. I do mini treatments (I take care of a 2 year old), so not as effective as real treatments, but my pattern is I treat so I can eat. Treat myself, eat, treat myself again when I can’t eat the next time. I wouldn’t take the time during the day to stick myself with needles if it didn’t provide me with significant relief, believe me.

    So acupuncture does work for NVP. It doesn’t rid your first trimester of the experience, but it makes life much happier. This is less an advertisement for acupuncture and more a counter-balance to the comment that acupuncture isn’t effective.

    Thanks.

    1. I too thought that last sentence regarding acupuncture was very brief and decisive sounding for something I found DOES work personally. I was reading this because I am pregnant with my 3rd, am 6 weeks along and not feeling sick yet as I did with my first two and feeling anxious about it because he grass is always greener on the other side. It is reassuring when you can’t feel movement yet or listen for a heartbeat to feel some symptom that your baby is well, even if it is miserable. With my second I started seeing am accupumcturist around 8 weeks after feeling sick for 2 and being sick of it! In my first pregnancy I was sick until 10.5 weeks. With my second after starting acupuncture I was much more mildly ill and then completely better at 10 weeks.

  7. Excellent summary! Might be worth including that Diclegis is actually a combination of two otherwise OTC medications (doxylamine AKA Unisom and B6) and that its effect size in studies has been very small… more serious options for nausea control include ondansetron AKA Zofran.

  8. i am 5 days away to the 2nd trimester and i have not had any morning sickness …though i have all the other symptoms and bump already showing . i can also feel my baby move . was wondering if am among the lucky ones

  9. I had a miscarriage in early December last year at about 12 weeks. I had had no morning sickness. I’m now five weeks pregnant and I’m increasingly anxious and paranoid as so far no sickness this time either. I think I’m feeling slightly nauseous from time to time but not sure if it’s my mind playing tricks on me. I’m going to sleep each night hoping I’ll wake up sick the next day.

  10. Do you know why there is a spike in miscarriages at week 8? I would expect that the odds for miscarriage for either group would be higher initially (weeks 5, 6, 7), then slowly decline (maybe decline at a quicker rate for the nausea group).

    1. I do not know for sure. But my best guess is that many early losses go unrecorded, and that some miscarriages are not detected until the first doctor’s appointment around 8-9 weeks.

  11. Was there anything in the study about duration of morning sickness and miscarriage rate? It sounds like the most common pattern is for morning sickness to last throughout the first trimester. What if it starts before the 8 week mark, but only lasts a week or two?

  12. Hi Amy, thanks for your article. I have 4 children and experienced NVP with 3 of the 4, interestingly the only one I didn’t have NVP with, and didn’t even have any nausea with was with our son with down syndrome! Since then have had 3 early miscarriages and did not have anything more than super mild nausea with them. Currently 8+6 and having the worst NVP of any of my pregnancies. I am nearly 39 now, so your article and stats on only having 1/5 of the chance of miscarriage as others my age who don’t experience NVP is super reassuring! Thanks again

  13. Thanks for an interesting article. I do wonder about the percentages for women experiencing sickness though – and whether they change over time or with (a healthier??) diet. Only because, anecdotally, only two of the pregnant women I’ve known have said they had any nausea – the rest, myself included, have experienced nothing at all (although it did worry me earlier that I had none – I’m well into the second trimester now). 80% seems awfully high, makes me wonder about reporting bias…

    1. You are lucky! I had horrible nausea with all three, as did most women I know! Anecdotal evidence aside, I have no idea how representative the samples were, or whether women are likely to exaggerate or discount their nausea after the fact. I have heard people talk about plant based diets lowering the risk of nausea, but it did not help me.

  14. This article been helpful I’m a 7-week today and since 3 days ago I’ve been feeling the nauseous in the morning is drink a little bit of ginger ale 3or 4 saltine crackers and it helped me a lot by doing this in Natural way. If I only have nauseous but it’s not severe well I do is put a little bit of alcohol and a little washcloth or tissue and smell it a couple of times and it cut meat the nauseous at once… I know probably this will not work to everybody but its natural way you should try it every pregnancy and everybody is different.

  15. I don’t agree. I had severe nausea with vomiting from week 6 to week 16. At week 16 I had a miscarriage. I was 36 years old and it was my first pregnancy.

  16. I’ve had 2 missed miscarriages and in both I had severe morning sickness from 5 weeks until the miscarriage at 12 weeks and then 8 weeks. I think it should be mentioned in your article that there is a chance that morning sickness and a healthy pregnancy are related but it has not been proven. You lead readers to believe that it is proven through the study by your use of “strongly” and other poorly chosen words.

    https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/expert-answers/nausea-during-pregnancy/faq-20057917

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