Why do so many of us barf up breakfast-especially when baby is at such critical stages of development? The truth is that we don't know what causes morning sickness, at least not with any certainty. Here are three of the most common theories:

Theory #1: Blame it on the hormones

When you're creating a new life, Mama, your body is flooded with hormones. Remember that hormone you needed to get a positive reading on your home pregnancy test? That's your human chorionic gonadotropin (hCG). While you have lots of hormones swirilng around in your system right now, hCG in particular is often blamed for making women feel queasy, perhaps because it peaks-to as high as 300,000 mIU/ml of urine- when morning sickness symptoms are typically at their worst, during weeks 9-12 of your pregnancy. (By comparison, the pregnancy test you bought likely registered at just 20 mIU/ml!)

Then again, it could be that rising levels of hCG trigger your ovaries to produce more estrogen. Women who use hormonal contraception or undergo horomone replacement therapy, both of which increase estrogen levels, often experience nausea, too.

You're also producing more progesterone, which relaxes not only the muscles in your uterus- discouraging early contracts, so you don't expel your growing baby- but also the muscles of the stomach and intestines. This makes digestion less efficient, which can lead to heartburn and acid reflux (not to mention burping and flatulence). Good times right?

Theory #2: Consider it a sign of a nutritional deficiency

Some experts believe that morning sickness is caused, at least in part, by low blood sugar, although there are no studies to support this theory. (Nausea can definitely be worse on an empty stomach, however, so you';; want to try and eat something, even if dry toast is all you can keep down.) Others believe that mamas-to-be are often deficient in key vitamins and minerals, which may contribute to or exacerbate that queasy feeling:

There are 8 different vitamins that make up the B family. Several studies have shown that taking supplemental B6 can significantly reduce the symptoms of morning sickness. There's also some evidence to suggest that the majority of Americans, pregnant or not, have some level of magnesium deficiency. We talked a little about soil depletion in week 3, the idea, backed up by plenty of research, including a landmark 2004 study from University of Texas at Austin's Department of CHemistry and Biochemistry, that the fruits and veggies grown today aren't as nutritionally dense as those gronw decades ago. Combine that with the stressful lifestyle and a high sugar diet (two more things that deplete magnesium stores), and its no wonder that many of us are desperate need of a mineral boost. 

You can find magnesium in supplement form, but the best way to get this calming mineral is directly through the skin. Topical magnesium oil, which you can rub on your stomach and the insides of your arms and legs (think thin-skinned areas) just like lotion. Magnesium is also great for the bowels... keeps things... moving.

Theory #3: Chalk it up to survival of the species

Back in week 3 (check our Week-by-Week on Instagram), we talked about the fact that Mama's heightened sense of smell might be all about survival- if she's better able to smell spoiled, rotten, or poisonous food in the wild, the logic goes, she may be better able to protect her growing baby. According to a couple of biologists at Cornell University, morning sickness may provide a similiar protection, encouraging mama to avoid or regurgiate potentially harmful foods. 

During the first trimester, your immune system is suppressed- this makes your body less likely to label and attack baby as a "foreign intruder", but renders you more susceptible to foodborne illness. That may explain why Japanese women experience morning sickness at the highest rates of any industrialized society in the world (at least, according to the Cornell researchers)- raw fish, highly susceptible to contaminants, is a Japanese dietary staple. Societies with the lowest rates of morning sickness, on the other hand, eat a diet composed primarily of "safer" plant products like rice and corn. Interestingly, women who experience morning sickness are less likely to miscarry and more likely to deliver healthy babies, another indiciation that nausea and vomiting may be protective measures.

Taking The Queasy Way Out:

Now that we know what causes morning sickness- well sort of- let's get to work soothing those symptoms, Mama. First you'll want to start with the basics. As best you can:

• Eat a balanced nutrient-rich diet.

• Get adequate sleep (at least 8 hours a night)

• Exercise regularly (even if that just means squeezing in a walk around the block)

• Get loads of fresh air and sunshine. 

If you find that certain smells or aromas are suddenly turning your stomach, consider switching to unscented toiletries and household products (don't be afraid to ask hubby to switch his products off if necessary) for the next few weeks. And even though it may be difficult to keep food down, try not to let yourself get too hungry.

Nausea + an empty stomach = a greater chance of losing your lunch. 

If bland foods are the most palatable right now, try to choose nutritionally dense options, such as brown rice and sea salt, avocado on whole-grain toast, bone broth, or banans and natural almond butter. You may find that eating a late-night snack or nibbling on some crackers before getting out of bed in the mornings helps, too, in part by keeping your blood sugar stable.

Of course, even when you're being diligent about your health, nausea, dizziness, or the urge to purge can strike out of nowhere... good luck mamas! You can make it through anything.