Morning sickness is experienced by more than half of all pregnant women and has long been considered one of the unfortunate side effects of pregnancy. Women all over the world hate morning sickness and many take different measures to reduce its effects.
However, morning sickness may be a defense mechanism to protect the unborn child. Numerous research has suggested that nausea and vomiting is triggered purposefully to expel potentially harmful foods such as meat, which would have contained parasites in years gone by, and strong tasting vegetables that may contain plant toxins. These materials could harm the baby at a crucial stage when its organs are forming.
The nausea and vomiting reaction would then deter the mother-to-be from consuming that item again. Likewise, tea and coffee suddenly smell disgusting to a pregnant woman, even if she normally likes them.
This may be to protect her baby from the negative effects of caffeine, which increases the risk of miscarriage. The same effect is sometimes seen with cigarette fumes.
So morning sickness directs the expectant mother into a healthy lifestyle, which she might not otherwise adopt.
Another theory about morning sickness suggests that it may be a side effect of the mother’s newly immune-compromised state. All pregnant women have a certain degree of immune suppression because half of the baby’s genes come from the father and are foreign to her, therefore, the immune system has to be restricted in order to prevent her from rejecting it as a foreign body.
Scientists also hypothesize that there is a constant physiological battle between the baby and the mother over how nutritional resources are divided between them. The baby needs enough resources to continue to develop, while the mother needs to be healthy in order to carry the pregnancy to term.
A side effect of this internal battle is thought to be morning sickness. This theory is called "gestational conflict."
The problem with this theory is that we are the only placental mammals that experiences morning sickness during pregnancy. If a conflict in division of resources were the only reason people experienced morning sickness, then humans would not be the only species to suffer from it.
This led researchers to believe that the first theory -- that of protecting the baby from noxious substances -- probably held more weight. They noted that in communities that have entirely plant based diets, excluding all meat, women have much less morning sickness. So do societies that consume less alcohol.
Animals are thought to be lucky enough to escape morning sickness because they have a relatively plain diet of only a few staples and we eat a larger variety of foods than any other mammal. Animals then have less chance of poisoning their embryos.
Scientists think this is why women who report severe morning sickness usually have healthy babies. Although this is not always the case. Absence of morning sickness can indicate miscarriage.
So next time you berate the fact that you can’t leave the house without throwing up, just remember, it’s the baby’s survival mechanism.
Sources:
Morning Sickness: Adaptive Cause or Nonadaptive Consequence of Embryo Viability? vol. 172, no. 1 the American naturalist July 2008. Full Text: http://www.colorado.edu/eeb/facultysites/flaxman/pubs/FlaxmanSherman08.pdf
Morning Sickness, American Pregnancy Association. Web. 17 November 2011. http://www.americanpregnancy.org/pregnancyhealth/morningsickness.html
Joanna is a freelance health writer for The Mother magazine and Suite 101 with a column on infertility, http://infertility.suite101.com/. She is author of the book, 'Breast Milk: A Natural Immunisation,' and co-author of an educational resource on disabled parenting.
She is a mother of five who practiced drug-free home birth, delayed cord clamping, full term breast feeding, co-sleeping, home schooling and flexi schooling and is an advocate of raising children on organic food.
Reviewed November 18, 2011
by MIchele Blacksberg RN
Edited by Malu Banuelos