morning sickness

Some degree of morning sickness is experienced by almost every pregnant woman (in interviews conducted after the peak period of pregnancy sickness, up to 90% of women reported some amount of nausea or food sensitivity). Because it is so common, the concept of morning sickness as a 'sickness' (read 'malfunction') is suspect.

One theory that is starting to gain acceptance is that the food aversions, nausea, and vomiting associated with pregnancy sickness serve as a mechanism to prevent the pregnant mother from consuming toxins that might harm the developing fetus.

Many of the foods humans commonly eat are loaded with carcinogens and other toxins. For example, black pepper contains sarole, a substance which is both carcinogenic and mutagenic. Tea consumption during the first trimester been associated with the development of spina bifida in fetuses. Grilled meats are loaded with carcinogens. The foods most commonly cited by pregnant women as causing nausea, vomiting, or being generally aversive are foods that have the highest concentrations of substances that could be harmful to a developing fetus.

The developing fetus is most vulnerable to toxins during the period from about 2 weeks after conception to roughly 10 weeks into development. During this period, the major organ systems are being formed. Pregnancy sickness is most pronounced during this period, and it drops off and often disappears afterwards.

Perhaps the most telling evidence in support of this theory is that women who report no pregnancy sickness are about 3 times more likely to experience spontaneous abortion (i.e. miscarriage) than women who do have pregnancy sickness.

It's not an illness, it's an adaptation!

This theory was developed by Margie Profet. For more information, see her article: Profet, M. (1992). Pregnancy sickness as adaptation: A deterrent to maternal ingestion of teratogens. In J. Barkow, L. Cosmides, & J. Tooby (Eds.), The adapted mind (pp. 327-366). New York: Oxford University Press.

factgirl: In response to your various comments: All scientists develop hypotheses using induction. People do not require graduate degrees to have good ideas. Margie Profet may not have done scientific research herself, but that does not invalidate her theory. Some people do research, some people process it and form hypotheses, few people are good at both. Here is some relevant research in support of Profet's theory of morning sickness:

*regarding the toxicity of various foods: Buttery, R.G., Guadagni, D.G., Ling, L.C., Siefert, R.M., and Lipton, W. (1976). Additional volatile components of cabbage, broccoli, and cauliflower. Journal of Agricultural and Food Chemistry, 24, 829-832; Nesse, R.M., and Williams, G.C., (1994). Why We Get Sick. New York: Times Books Random House.
*studies on the foods pregnant women find aversive: Tierson, F.D., Olsen C.L., and Hook, E.B. (1985). Influence of cravings and aversions on diet in pregnancy. Ecology of Food and Nutrition, 17, 117-129; Dickens, G., and Threthowan, W.H. (1971). Cravings and Aversions during pregnancy. Journal of Psychosomatic Research, 15, 259-268.
*describing the typical time course of morning sickness: Gadsby, R. (1994). Pregnancy sickness and symptoms: your questions answered. Professional Care of Mother and Child, 4(1), 16-17.
*review of fetal development: Vasta, R., Haith, M.M., and Miller, S.A. (1995). Child Psychology: the Modern Science, 2nd Edition. New York: John Wiley and Sons, Inc. (Chapter 5)
*describing the connection between pregnancy sickness and spontaneous abortion: Yerushalmy, J., and Milkovich, L. (1965). Evaluation of the teratogenic effects of meclizine in man. American Journal of Obstetrics and Gynecology, 93, 553-562.
*recent review article supporting Margie Profet's theory of morning sickness: Flaxman, S.M., and Sherman P.W. (2000). Morning sickness: a mechanism for protecting mother and embryo. Quarterly Review of Biology, 75(2), 113-148.
*association of tea and spina bifida: Correa, A., Stolley, A., Liu, Y. (2000). Prenatal tea consumption and risks of anencephaly and spina bifida. Annals of Epidemiology, 10(7), 476-477.

A word from someone who has both experienced morning sickness in all its glories as well as read some of Margie Profet's articles: hmmmm.

Margie Profet holds two Bachelor's Degrees, one in political philosophy, one in physics. She spent two years in Germany programming computers, and three years in San Francisco working part time jobs and "thinking". Though sometimes referred to as "Dr. Margie Profet" she holds no postgraduate degree and no University position.

After her paper on pregnancy sickness was published in 1986, she went on to produce two more theories. One allergic reactions, the other regarding menstruation being a form of expelling toxins from the body (when interviewed shortly after her article was published she did not know if other primates menstruate - all female mammals do). She won a Macarthur Genius award in 1993 and went on sabbatical to write Protecting Your Baby-to-Be : Preventing Birth Defects in the First Trimester. She has never conducted any scientific study on any of her theories, she relies instead on anecdotal evidence from her family members.

Here is a short list of her dietary cautions:

Good foods
- fruits and fruit juices
- milk and plain yogurt
- processed grains made into bland breads, pastas, and other starchy foods
- cooked fresh eggs
- fresh meat, boiled or in microwave

Food to be cautious about--eat only in small quantities
-vegetables that are not bitter or pungent (green beans, carrots, tomatoes and peas
-oils and oily foods
- dessert flavoring derived from bitter or pungent plants (chocolate, vanilla, ginger)

Food to avoid in first trimester
- pungent or bitter vegetables such as broccoli, Brussels sprouts, and peppers
- all spices and herbs
- onions, garlic, hot peppers and mustard
- mushrooms
- potatoes
- barbecued or burned foods
- beverages derived from bitter plant parts (i.e., coffee, tea, herb teas, colas)

Ok so there are the facts, here is my opinion. Miss Profet's book is yet another piece of the information bombardment that pregnant women face. Eat this, don't eat that, lay on your left side, buy a bunch of stuff - all at a time when you feel a mix of emotions and physical distress you can't imagine unless you've experienced it. It pulls our attention away from other, sound science that says eat a balanced diet and exercise.

She gives parents who have children with special needs to obsess, "was it something I did?", and all with no science backing her up. She could've waited to publish her book to the public until after a study or two, but didn't. Irresponsible. I, for one, am sick of "Flavor of the Month" pseudo-science being shoved at me from all sides with interesting titles and hot air backing it up.

You are completely correct radlab0, people do not require graduate degrees to have good ideas, I hope I have one someday.

My problem is not at all with Miss Profet's theory, it is with her adaptation of that theory for the consumer. She outlines a diet for pregnant women with boiled and microwaved meat? That is making me nauseous now! Potatoes have less chance of producing a child with Spina Bifida than fluoridated water (the data from the potato-spina bifda study says that because there is a high concentration of SB in Ireland, potatoes must be the culprit - boolean logic fails us again). Ginger RELIEVES morning sickness. ALL spices and herbs? What about Red Raspberry Tea Leaf - given to pregnant moms to help keep those lady parts healthy?