That first glimpse of two pink lines–can it be?–and your heart start to pound with excitement. You’re pregnant!
But after a few moments of celebration, you descend back to earth. Okay, you’re pregnant, but for how long? Will this pregnancy stick?
You have entered a new, more hopeful limbo than the much bemoaned two-week wait. But it’s still no picnic.
We all know that miscarriage is very common, especially early in pregnancy. And for most women, good info about viability does not come until the first ultrasound, usually performed at 8-10 weeks.
Undergoing fertility treatments is less fun than a hangover. But they have one silver lining: Once pregnant, you receive information about your chances of a healthy pregnancy much earlier, from your “betas”–blood tests of your beta hCG (Human Chorionic Gonadotropin) levels.
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.
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.
Three years ago, sitting with my 15-month-old son and my husband during a long layover, on our way back home from Norway, I felt a sudden gush of warm blood.
So much for my miracle pregnancy, I thought. I was only six weeks along and certain I was miscarrying.
Our return trip was already off to a poor start. United Airlines had cancelled our original flight from Newark home to San Francisco. Then, to rub salt in the wound, they refused to refund our first-class tickets.
We never fly first class, but had made an exception for this trip. We were travelling overseas with my 15-month old son and facing a 9-hour jet lag. The chance of sleeping on route, we decided, was worth the extra cash. We had bought our tickets a year in advance to lower the cost.
But United, being United, told us wewould have to request a refund, and then maybe theywould grant it. And–perhaps just for kicks–they refused to let us access the first-class lounge while in Newark, because our replacement tickets were now in Economy.
My husband–who nevers argues with anyone behind a counter and hates it when I do–spent half an hour arguing with their “customer service” that they should give us passes to the first class lounge. After all, we had paid for first-class tickets even if we no longer had them. But no dice.
So there we were, exhausted and enraged. I had not slept in over 24 hours. My son, sick for the last 3 days with a high fever, had nursed continuously the entire flight from Oslo to Newark. And then I started bleeding.
At that point, I contemplated tweeting, “United, you ate my baby,” but decided against publicly sharing my pregnancy or what I assumed was an impending miscarriage.
The pregnancy had been a surprise, but a welcome one. We had taken over a year to conceive my son. This time we had not been trying. I was still breastfeeding, and my cycles had only resumed a month earlier. We were planning to wait a few more months and then start trying for #2, expecting that it could easily be another 6 to 12 months before we conceived.
The bleeding tapered off by the next morning. I had no pain or cramping, so little fear of an ectopic pregnancy. And I still felt pregnant: nauseated, tired, and lightheaded.
I called my OB, but they could not fit me in for another 5 weeks. Until then, they told me, just sit tight. Oh, and assume that I was still pregnant, because a miscarriage would have caused several days of heavy bleeding.
I found another OB.
My new OB ran tests. My HCG levels were normal, but my progesterone was low, perhaps because of the nearly constant breastfeeding, the lack of sleep, and the stress. She could not say for sure. She prescribed progesterone supplements for the rest of my first trimester.
Progesterone helps build up and maintain the uterine lining for implantation of the fertilized egg. High levels of progesterone are required to sustain an early pregnancy. But taking progesterone supplements during the first trimester to prevent a miscarriage is controversial.
Over half of miscarriages result from chromosomal abnormalities, and no amount of progesterone will save these pregnancies. A 2013 review of randomized trials, however, found that while progesterone supplements did not alter the risk of miscarriage for pregnant women as a whole, they did significantly lower the chances of miscarriages for women with 3 or more prior miscarriages.
And for women like me, with a threatened miscarriage (defined as any bleeding within the first 20 weeks of pregnancy), who have more than double the normal odds of a miscarriage*, progesterone supplements appear to cut the risk of miscarriage in half, and oral progesterone, as opposed to suppositories, may be especially effective.
So, although I will never know for sure, my OB may have saved my pregnancy.
A Subchorionic Hematoma
At that initial visit, she also performed an ultrasound. The fetal heartbeat was loud and clear, fast and reassuring, racing along like a rabbit’s. When I heard my baby’s heartbeat, I fully exhaled for the first time in days.
Less reassuringly, the ultrasound revealed a subchorionic hematoma–a blood clot next to the placenta and the cause of my bleeding.
Pregnancies with a subchorionic hematoma are considered high risk. They have a higher risk of miscarriage (17.6% versus 8.9%), stillbirth (1.9% versus 0.9%), and placental abruption (3.6% versus 0.7%). They have a slightly higher risk of preterm delivery (13% versus 10%) and for the waters breaking before labor starts (tv-style labor).
The risk varies by the location of the hematoma. Pregnancies with recurrent bleeding or with hematomas located between the placenta and the uterine wall (retroplacental hematomas) have a higher risk of miscarriage and other pregnancy complications like placenta abruption. Because of the risk of placental abruption, bleeding in the second and third trimesters require immediate medical attention.
As worrisome as these statistics sound, most subchorionic hematomas resolve on their own, as mine eventually did. By 11 weeks, we could no longer see the hematoma on an ultrasound. And thankfully, rest of my pregnancy was uneventful. I gave birth to healthy baby girl, who in a few months will turn 3.
Do you have a story of bleeding in early pregnancy? Was a cause detected, and how did things turn out?
Footnote
*About 20% of women experience bleeding during early pregnancy. Figuring out their chances of a miscarriage is far from simple.
One commonly cited statistic states that roughly 50% of these women eventually miscarry. Some digging reveals that this claim derives from a 1981 obstetrics textbook rather than recent research. (Lots of researchers cite papers that cite papers that cite this textbook, and I am willing to bet that none of them have read the original research behind this claim.)
If bleeding starts after detection of a normal fetal heartbeat, most prospective studies find a much lower rate of miscarriage, of 3.4-5.5%.
References
Haas DM, Ramsey PS. Progestogen for preventing miscarriage. Cochrane Database of Systematic Reviews 2013, Issue 10. Art. No.: CD003511. DOI: 10.1002/14651858.CD003511.pub3.
Getting pregnant is a numbers game. Here’s what every woman should know about her odds of success in her late 30s and early 40s.
One of my former colleagues became pregnant her first shot out of the barn, the first month off the pill. Her story would hardly be noteworthy, except that she was 41 at the time.
She wanted to tell other women about her experience, she confided to me. She saw it as a sign that women can have children after age 40.
I simply nodded in response, while I privately wondered if she had not just been very lucky.
But–and this is key–how lucky?
Having a baby in your 30s and early 40s–and earlier, for that matter–is always a chance event. There will be outliers. Some women will give birth naturally at 44. Some women will suffer from early menopause at age 30. But outliers tells us little about the norm.
Anyone who wants to play the conception game, especially if they are postponing childbearing, needs to put anecdotes aside and try to grasp the actual odds. Here’s what every woman needs to know:
