Maternal-fetal conflict

= Definition =

When mother and offspring’s (in utero) ideas of the allocation and amount of resources differ, maternal-fetal conflict arises. This conflict generally presents as a health problem for the mother, fetus, or both.

= Examples of use in context =

Maternal-fetal conflict can occur even at the early stages of pregnancy. According to Nesse &amp; Williams (1994), 78 percent of all fertilized eggs are not implanted or spontaneously aborted by the mother at the beginning of pregnancy, mostly due to the fetus’ chromosomal abnormalities. It seems as if mothers have an adaptation in which they can detect these abnormalities and spontaneously abort in order to avoid investing in a baby with low fitness. So, the fetus has evolved an adaptation to combat this spontaneous abortion- the production of human chorionic gonadotropin (hCG), a hormone that secretes into the mother’s bloodstream. hCG keeps the fetus implanted because it keeps the mother from menstruating, the mother’s body interprets high levels of hCG as a sign that the fetus is healthy and thus does not spontaneously abort. Towards the end of pregnancy, the placenta, a fetal product, secretes a hormone that hinders the effectiveness of the mother’s insulin. But, the mother continues to produce more insulin, which lowers blood sugar levels. The fetus might see this as a way for the mother to limit how much nutrients the fetus gets. The fetus will then try to get as much as it can. Sometimes, this can result in gestational diabetes (Barash 2001).

= Scientific background  =

Maternal-fetal conflict is a branch of the theory of parental-offspring conflict, developed by Robert L.Trivers in 1974. He stated that parental-offspring conflict comes from the difference in parental investment and the child wanting more than the parent is willing to give. David Haig, an Australian evolutionary biologist and geneticist broadened this theory to discuss the conflict among mothers and their offspring in utero. He believed that fetuses would be selected to take more resources from the mother than it would be optimal for the mother to distribute. In Buss’ book, Evolutionary Psychology: The New Science of the Mind, he describes maternal-fetal conflict, “A mother contributes 50 percent of her genes to the fetus, but the fetus also receives 50 percent of its genes from its father. Mothers will be selected to channel resources to the child who will yield the greater reproductive benefit. This child, however has a greater stake in itself than it has in the mother’s future child. Therefore, selection will create mechanisms in the fetus to manipulate the mother to provide more nutrition than will be in the mother’s best interest to provide” ( Buss pg.216).

= Debates =

Some evolutionary biologists have tried to use maternal-fetal conflict as the cause for preeclampsia, a condition characterized by a mother’s high blood pressure and protein in her urine (Preeclampsia Foundation). At the beginning of pregnancy, the placental cells damage the arteriolar muscles that control blood flow to the fetus. A mother’s blood pressure is elevated when something constricts her other arteries and therefore will increase blood flow to the fetus. When a fetus wants more food and nutrition (provided by the mother’s blood), it will secrete substances into its mother’s bloodstream that will constrict her arteries (Buss 1999). This is believed to cause preeclampsia for the mother. Also, data states that mothers with increased blood pressure during pregnancy have lower rates of spontaneous abortions (Haig 1993). In the medical world, preeclampsia does not have a definite cause. According to the Preeclampsia Foundation, theories for the cause of preeclampsia are; high body fat, insufficient Magnesium Oxide and B6, Calcium deficiency, endothelial activation and dysfunction, Hemodynamic vascular injury, and autoimmune disorders.

The largest risk factors are; -Previous history of preeclampsia, particularly if onset is before the third trimester -History of chronic high blood pressure, diabetes or kidney disorder -Family history of the disorder (i.e., a mother, sister, grandmother or aunt who had the disorder) -Women with greater than 30% Body Mass Index (BMI). -Multiple gestation -Over 40 or under 18 years of age -Polycystic ovarian syndrome -Lupus or other autoimmune disorders such as rheumatoid arthritis, sarcoidosis or MS. (Preeclampsia Foundation)

= References =

Barash, David P. Revolutionary Biology: The New, Gene-Centered View of Life. Transaction, 2001. Print.

Buss, David. Evolutionary Psychology: The New Science of the Mind. Allyn and Bacon, 1999. Print.

Haig, David. "Genetic Conflicts in Human Pregnancy". Quarterly Review of Biology 68: 495-531. 1993.

Nesse, Randalph, George, Williams. Why We Get Sick:The New Science of Darwinian Medicine. Times Books, 1994. Print.

Trivers, R.L. “Parent-offspring conflict”. American Zoologist 14: 249-264. 1974. http://www.preeclampsia.org

= Image/Figure =

For a more thorough explanation of preeclampsia,

= Author =

Erica Lupinacci