The Mystery of Morning Sickness and Other Symptoms

"Five weeks on the dot." That's when Emma Pattee first felt the inner rocking of morning sickness. "It's a very hard time to feel sick, because you probably haven't told many people that you're pregnant yet."

Pattee struggled with juggling work while feeling extremely ill in those first months. The freelance writer wasn't comfortable telling clients about her pregnancy right away—so for the most part, she suffered in silence. Whenever she drove somewhere, she'd have to pull over and throw up.

While most women experience nausea and/or vomiting in the first trimester of pregnancy, a much smaller percentage (0.3 to 2 percent) will face a severe version of morning sickness called hyperemesis gravidarum, which can require hospitalization due to dehydration and weight loss.

Despite the ubiquity of nausea and vomiting during pregnancy, the exact cause of morning sickness and why some people experience it worse than others remains unconfirmed.

"If you've had prior history of morning sickness in a previous pregnancy, you're more likely to get it again," Conti said. "But if you've never been pregnant before, it's really hard to predict."

Kathy Fray, senior midwife and author of Oh Baby: Birth, Babies & Motherhood Uncensored, suggests that even without a definitive cause, we know these symptoms aren't useless—they're a sign our body wants us to rest.

The most common theory is morning sickness is due in part to a rise in pregnancy hormones, including hCG and progesterone. Fray said progesterone "acts as a smooth muscle relaxant, to inhibit the womb from expelling its contents." In other words, it's helping to prevent a miscarriage.

So while morning sickness can make you miserable, it might also be a sign your body is working hard to make a safe space for your baby.

Unfortunately, our jobs and personal responsibilities aren't as adaptive as our bodies, and a common reaction to morning sickness is to power through it. After all, you don't even look pregnant yet. You should be able to go to work and clean the house and spend time with friends just fine—right?

Not so fast. Your pregnancy might still be invisible to most, but there is so much happening in those first few weeks and months. You're building a brand-new organ. And a human! And that takes a lot of energy.

"[Morning sickness] is the woman's body doing everything in its power to make her rest," Fray said. "Rest, rest, rest!"

Exhaustion in the first trimester is another common symptom that often accompanies nausea. But exhaustion in early pregnancy also has a tendency to catch women off-guard with its severity.

"It almost feels like you've got mono. Or maybe you slept all night and it feels like you never actually went to sleep," Conti said.

"It's an extreme kind of exhaustion—which I think people don't really talk about," added Pattee, who often struggled to get out of bed.

Progesterone is the likely culprit with first trimester exhaustion as well, which rises quickly at the start of pregnancy. Your blood volume is also increasing at this time, requiring your heart to beat faster and stronger, distributing all that blood to develop the placenta and fetal circulation. It's like you're working out, even when you're sitting on the couch watching Netflix.

Can you guess what midwife Fray advises? Rest!

Suddenly a smell you've hardly noticed before is intense and offensive. Many women report an unpleasant sharpening of their olfactory senses during pregnancy, which often accompanies morning sickness, or worsens it.

One study, published in the peer-reviewed journal Chemical Senses from Oxford Academic, found pregnant women are especially sensitive to the smell of cooking foods, cigarette smoke, perfume and spices.

However, another study, published in Medicinski Pregled from the Society of Physicians of Vojvodina of the Medical Society of Serbia, found no increase in sense of smell of pregnant women compared to women who are not pregnant. This led researchers to hypothesize that pregnant women are more turned off by smells they were already capable of detecting—they're just more grossed out by them now.

Again, it is likely pregnancy hormones are to blame. But no direct causation has been determined.

When Fray was pregnant with her first baby, she craved yogurt pops. With the second, she craved orange popsicles. And with the third, it was caramel chocolate. With each pregnancy, the experience of eating the food she craved most was euphoric. As soon as she gave birth to each baby, those cravings went away.

"It is so cool of Mother Nature to steer the mother toward her physical needs," Fray said.

It makes sense that pregnant women would experience a strong desire for the food they need to support a healthy pregnancy. And most doctors and midwives agree that it's smart to listen to your body—to a certain extent.

But food cravings have also been linked to gestational weight gain, which, in excess, can have adverse effects on mom and baby.

Additionally, there can be a disconnect between what women crave during pregnancy and the nutrients they need most, according to a 2014 article in Frontiers in Psychology. It seems cravings during pregnancy are inconsistent on a global scale: Pregnancy cravings are most prevalent in North America and aren't really a thing in some other countries. In places where it is prevalent, they crave very different things, depending on their culture's cuisine.

This could indicate cravings are less related to a need for certain nutrients and more related to the comforting nature of the foods we love most—combined with the fact that in cultures that encourage restraint, women feel a little more freedom to indulge during pregnancy.

The common narrative of extreme cravings during pregnancy might just inspire those cravings. (Try thinking about how it feels to crave ice cream. Kinda makes you want ice cream, right?)

That said, a few yogurt pops aren't going to hurt you. And when you're working on cooking up a whole human from scratch, you shouldn't feel shame in allowing yourself to enjoy the foods you most desire—as long as you're still prioritizing your health and the health of your baby.

There is so much we don't know about why we experience certain symptoms during pregnancy. It can be tempting—especially at first—to go looking for all of the answers. Especially when we have access to endless information and opinions, conflicting advice and self-diagnoses.

But everyone experiences pregnancy differently, so if your pregnancy symptoms seem especially unusual or intense, seek medical advice—and talk about it! It's always helpful to hear what other women have been through, too. Our bodies are powerful and mysterious. And you deserve a nap.