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What Causes Morning Sickness

Baby Bump: What Causes Morning Sickness

Morning sickness can last for one day or nine months. Mamas-to-be may experience waves of nausea or hours of vomiting. And, most women are curious to know what causes the sickness. In many studies, researchers test or compare human behavior to animals. Fortunately for other living reproductive animals, humans appear to be the only species that get ill during the expecting months, which has made it tough to decipher the cause.

To see what researchers think may cause morning sickness,


In the July issue of the journal American Naturalist, Samuel Flaxman and his colleague Paul Sherman said morning sickness is triggered in these specific circumstances:

  • The sight, smell, or taste of meats and strong-tasting vegetables, which were historically likely to contain foodborne microbes or birth-defect-inducing chemicals
  • Alcohol and cigarette smoke.

The researchers believe the mother's body is naturally alerting her to stay away from harmful agents, thereby protecting the growing embryo.

While all of this sounds good, I have to wonder about the rest of us that didn't deal with the dreaded sickness. While pregnant with my daughter, I almost craved nausea because it made me feel secure. Having breezed through pregnancy and ended up with a healthy babe, I would never do that again.

Does morning sickness comfort you during pregnancy?

Join The Conversation
hottdana hottdana 9 years
I am 35 weeks pregnant with my second one and I am still throwing up!!! Last time medication works wonders for me, this time it didn't do a damn thing! I'm not expecting it to end until this baby shows her face and i am sooooo ready for that. I don't believe those findings because I don't smoke cigarettes or drink alcohol right now. some women get sick and some don't, just not fair but that's the way it goes.
macneil macneil 9 years
I had very bad morning sickness right up to delivery date for my first. I'm currently pregnant again and have been taking some pills - because I just couldn't cope with a toddler and vomiting all day long. I'm sick just once or twice in the morning now, and am nearly at 12 weeks, but don't really see it ending at 12 weeks because it didn't last time. I've read all the theories, but they still don't make much sense. Both times, I've had the strongest DEcraving for vegetables. If I eat vegetables, the next day I'm sick all day long, pills or no pills. Gwyneth Paltrow said she couldn't eat any healthy food and ate grilled cheese sandwiches and french fries throughout her pregnancy. It is the STUPIDEST survival trick imaginable, whatever nature has in mind. My second pregnancy ended in a miscarriage, and I had no morning sickness. So in a way i was happy when I got it this time. But not VERY happy. The thing is, I know LOADS of women who had no morning sickness at all and had the happiest, healthiest pregnancies and darling healthy babies. But for me, I think the sickness is a sign that it's going ahead as it should.
anniekim anniekim 9 years
I did not suffer from morning sickness in any of my 3 pregnancies and consider myself very lucky. I have a friend who just had her 1st baby. She was horribly nauseated her entire pregnancy regardless of eating or not etc. If she went a day without vomiting it was a good day. Usually she would throw up 3 or more times daily. She did not enjoy her pregnancy. I find it hard to believe that indigenous peoples do not feel pain during childbirth. This is the first I have heard of that. Could you point to a study Mishell?
rgrl rgrl 9 years
I had evening sickness with my son and all day sickness with my daughter (who is not yet born). It was pretty bad in the first trimester. With my daughter I sometimes got sick three times a day, could hardly hold any food down. Plus most foods seemed disgusting to me. No, I don't think it was a comfort to me. Achy boobs and no period were good enough to keep me comforted.
LizL LizL 9 years
I had morning sickness in my 1st trimester. It went away in my 2nd. NOW IT's BACK in my third trimester!! ARG!
tigerlily10 tigerlily10 9 years
I've had morning sickness for 7 months and it's not comforting in the least! Since I don't eat meat, drink alcohol and stay away from cigarette smoke, I'm not so sure about those findings. A lot of people have told me morning sickness is hormonal and is worse with baby girls, I don't know if there's truth to that or if it's just an old wives tale.
faerymagick15 faerymagick15 9 years
I never had morning sickness with any pregnancy except my ectopic pregnancy. I sailed right through both my term pregnancies with no nausea at all. If I am lucky for this IVF to work...I am HOPING for morning sickness!!! I think it will actually make me feel more secure after all my miscarriages.
SweetPeasMom SweetPeasMom 9 years
I am in the worst part of morning sickness right now at 8 weeks pregnant. I can tell you, it's not just linked to the sight and smell of food or alcohol or cigarettes or anything like that. Literally, I can have just eaten, or not eaten for hours and I'm sick. It was like this with the first one, except I didn't have a 2 year old to look after. It's awful. And NO! It's not comforting. It's horrible.
Greggie Greggie 9 years
Did anyone have sickness just in the morning? I don't know anyone who did. We all had the all day thing. Mine actually was worst in the evenings. I had it for 14 weeks with my boys and 22 weeks with my daughter.
MartiniLush MartiniLush 9 years
I had "all day sickness" for the first 10 weeks or so - I could barely eat anything. After that, I could eat everything in sight! (And did!)
Greggie Greggie 9 years
I don't think there's no morning sickness in certain cultures, I just think women are better "trained" to ignore it in some places. Same goes for the pain - for instance, someone who does hypobirthing successfully is going to feel less pain than someone who isn't at all prepared for birth, but that doesn't mean the pain isn't there. It's just a different mindset on how you deal with it. I was not comforted by morning sickness. Considering it kept me from eating anything at all, I fail to see how it protected me. And those suffering from hypermesis certainly aren't avoiding foods to protect the child.
luckyme luckyme 9 years
I was pretty sick for about 6 weeks. I still have a hard time eating mushrooms because they made me so sick. I always thought my morning sickness was linked to the crazy amount of hormones flooding my system. I have a sensitive stomach anyway, so I just attributed it to that. (And yes, when my morning sickness went away and I wasn't to the point that I could feel the baby move, I did freak out. It was definitely a bit of a comfort to me). And while I didn't drink alcohol when I was pregnant, my doctor did say that I could have a glass of wine if I wanted to in the last trimester. I tried a sip and it tasted so wrong! I think that was probably my body saying, "no way, Mama." Mishell, I've never heard about it being a cultural thing. That's interesting. Although, I have to disagree with you about the pain thing. They may not have epidurals and pain killers during child birth, but unless they are somehow numb or knocked out, they feel the pain. We as a culture may be over-sensitized to pain, but that doesn't mean other cultures do not feel any.
Mishell Mishell 9 years
My morning sickness was so bad that we have decided to any adopt future kids. If I ended up as sick with the next one as I was with the first I would be unable to take care of him. Getting pregnant again does not seem like a very smart choice. That being said, I think morning sickness is a cultural thing. I remember hearing in my college anthropology class that it is completely unheard of in indiginous cultures. But then so is pain during childbirth...
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