Preeclampsia and Nutritional Priorities
by Michel Odent

[Editor’s note: This article first appeared in Midwifery Today, Issue 112, Winter 2014.]

nutritious salad

[Photo by Jennifer Rosenberg]

The nature and the expression of pregnancy diseases vary among different species of mammals. It is notable that these differences are related to the nutritional priorities during the prenatal phase of development.

Interspecies Comparisons

Among carnivorous mammals, such as dogs, the priority at the end of pregnancy is the development of the bones of the offspring, which are much more mature at birth than the bones of other mammals. The nutritional priorities are therefore in terms of minerals, particularly calcium. It is significant that when the mother has difficulties satisfying the fetal nutritional needs, the pregnancy disease is the expression of hypocalcemia. Treatment is based on the intravenous administration of calcium. Where herbivorous mammals such as ewes are concerned, veterinarians use the term pregnancy toxemia. Among these mammals, the fetus is supplied almost entirely by glucose, consuming 40% of the blood sugar produced by the mother. The disease, also referred to as lambing ketosis, occurs in late pregnancy and is more common in the case of thin ewes pregnant with multiple fetuses. It is characterized by a destabilization of the glycemia that leads to fat catabolism. Treatment is based on the administration of glucose.

The Case of Homo Sapiens

What about Homo sapiens, the member of the chimpanzee family with an enormous highly developed brain? The spectacular brain growth spurt during the second half of fetal life is a specifically human trait. A conflict between the demands of the fetus and what the mother can provide without creating her own imbalances leads us to consider first the needs of the developing brain.

The specific nutritional needs of the developing brain have been recently clarified and are easily summarized through the concept of brain selective nutrients (Cunnane 2005).

It is significant that iodine is the only nutrient for which governments legislate supplementation, so that iodination of table salt is mandatory. In spite of such widespread legislations, iodine deficiency is the most common nutritional deficiency at a planetary level.

Iodine is a typical brain selective nutrient because of its essential role in thyroid hormone production, which, in turn, is needed for normal brain development (Cunnane 2005). It is significant that iodine is the only nutrient for which governments legislate supplementation, so that iodination of table salt is mandatory. In spite of such widespread legislations, iodine deficiency is the most common nutritional deficiency at a planetary level. It is the leading cause of preventable intellectual disabilities. The inability to conserve iodine is a meaningful aspect of human nature, and in situations of iodine deficiency, urinary excretion of iodine continues as usual. This inability suggests an adaptation to diets rich in iodine; this means diets including seafood. The needs are increased during pregnancy and lactation. The reinforced vulnerability to iodine deficiencies during pregnancy makes it significant that the human disease preeclampsia is characterized by impaired thyroid functions. In general, the level of free thyroxine (T4) is low in preeclampsia, while the level of thyroid-stimulating hormone (TSH) is high (Lao et al. 1990; Narin et al. 1990). The alterations of the levels of thyroid hormones reflect the severity of the disease. Furthermore, preeclampsia is associated with fetal and neonatal thyroid enlargement. Iodised salt became recently still more topical since it has been revealed that the salt used for producing the brine for pickling food—and commercialised sea salt—have no iodine added.

The brain, as a fatty organ, also has specific needs in terms of fatty acids, particularly long chain polyunsaturated fatty acids. More precisely, one molecule of fatty acid represents 50% of the fatty acids that incorporate into the developing brain. It is the so-called DHA (docosahaexenoic acid), a molecule of fatty acid as long as possible (22 carbons) and as unsaturated as possible (6 double bonds), which belongs to the omega 3 family. It is preformed in seafood.

I had wondered in the past if discussing these issues with pregnant women might have detectable effects in the perinatal period. In 1991, I started a study at Whipps Cross University Hospital in London. The objective was to evaluate the possible effects of simply encouraging pregnant women to consume sea fish (Odent, McMillan and Kimmel 1996). There was no eclampsia and no recorded preeclamptic toxaemia in the study group; in the control group there was one eclampsia with convulsions and two severe preeclamptic toxaemia. It is highly significant that the human pregnancy disease preeclampsia is associated with low concentrations of polyunsaturated fatty acids in maternal blood. However, whatever the circumstances, the levels of DHA—the brain specific fatty acid—remain stable (Wang, Kay and Killam 1991). The price of a stable DHA is an imbalance inside the omega 3 family that is at the root of a series of further imbalances, particularly in the system of prostaglandins. These facts suggest that when a pregnant human mother has difficulties satisfying the specific nutritional needs of the fetal developing brain, a cascade of physiological imbalances is induced.

After recalling that iodine is mostly provided by seafood and that DHA is preformed and abundant in seafood only, we can conclude that having access to the seafood chain during pregnancy appears as a guarantee that the specific nutritional needs of the developing fetal brain are met (Odent 2000).

Let us take this opportunity to emphasize that, from a physiological perspective, Homo sapiens has all the characteristics of an ape adapted to the coast (Odent 2013; Odent 1995). The daily needs in iodine are highly significant. Another characteristic is easily expressed with the language of biochemists. It is once more about the specific nutritional needs of the brain, particularly the developing brain. As a way to simplify, we can say that the human body is not very effective at making a molecule of fatty acid which is essential to feed the brain and that this molecule is preformed and abundant in the seafood chain only. Let us translate into the language of biochemists: one of the most significant characteristics of Homo sapiens is the association of an enormous highly developed brain with a weak delta 4 enzymatic system of desaturation (Carlson et al. 1987). This fact suggests that Homo sapiens is adapted to an environment providing preformed DHA.

What about Mothers Who Consume Land Food Only?

These considerations about the specific nutritional needs of the developing brain inspire questions about the many pregnant women who never consume seafood. The land food chain, in practice, can only provide the parent molecule of the omega 3 family, with 18 carbons and three double bonds (alpha linolenic acid). This implies that the enzymatic system of the mother must “desaturate” and “elongate” the molecule. This is facilitated by catalysts such as magnesium, calcium or zinc found in particular in vegetables, fruit, dairy products, etc. The important point, in practice, is to avoid the blocking agents (“anticatalysts”) of the metabolic pathways of polyunsaturated fatty acids. It is worth talking about these substances with all pregnant women, whatever their cultural background. The main blocking agents to mention are pure sugars (soft drinks, etc.), all alcoholic beverages and also trans fatty acids. Most molecules of trans fatty acids are originally the effects of oil processing and conventional methods of making margarines. They may be abundant in biscuits, cookies, certain cakes, etc.

We must add that very long chain molecules of polyunsaturated fatty acids—particularly DHA—are fragile and easily destroyed by oxidative processes. This is a way among others to explain the importance of anti-oxidative substances: it implies in practice daily consumption of fruits and vegetables. This is also a way to explain how cautious health professionals should be before prescribing iron, which is a powerful oxidative substance. Blood iron concentrations are high among women with preeclampsia (Rayman et al. 2002; Kim et al. 2012).

The importance of the issue of preeclampsia in relation to nutritional priorities is confirmed by the enormous differences in the prevalence of this pregnancy disease between poor and wealthy populations. It is also illustrated by the very low prevalence of preeclampsia in populations with high daily consumption of seafood such as those living in the Seychelles Island. Among 300 pregnant women recruited during their first antenatal visit in the framework of the Seychelles Development Study, there was only one case of preeclampsia (Wallace et al. 2008).

Beyond the Dominant Theories

Presenting preeclampsia as the expression of a maternal fetal conflict is a way to understand that a great diversity of factors can independently increase the risk. Faulty placentation, inadequate nutrition, macrosomia, multiple pregnancies, immunologic reactions and certain combinations of maternal and fetal genotypes are among these possible factors.

Any theoretical vision of preeclampsia must be confronted with the most intriguing aspects of the disease.

Preeclampsia is principally a disease of first pregnancies. Yet it has been demonstrated that the metabolism of omega 3 fatty acids is influenced by parity (Carlson and Salem 1991, 14, 15). It is as if brain development is a more absolute and unconditional priority in the case of a first baby. The DHA content of cord blood phospholipids depends on birth order; in other words, the capacity to provide preformed DHA is depleted with repeated pregnancy.

The association of preeclampsia with a reduced risk of cerebral palsy is also intriguing. This is the main conclusion of a study involving 59 very preterm babies who developed cerebral palsy and were compared with 334 controls (Murphy et al. 1995). Let us notice that in this study, none of the mothers had been treated by magnesium sulphate (the magnesium sulphate by itself may reduce the risk of cerebral palsy). In our view, the occurrence of preeclampsia implies that fetal brain development has been such an unconditional priority that there has been a transfer of nutrients (in particular DHA) in excess of the maternal safety limit. The consequence of preserving the needs of the developing brain at any price may be a maternal disease…but the risk of cerebral palsy is reduced.

It is easy to propose an interpretation of the increased risk of preeclampsia in twin pregnancies: two brains must be fed. It is of interest that a case of intrauterine death of a twin was followed by the resolution of the symptoms and signs of preeclampsia; the pregnancy continued safely for another seven weeks (Sarhanis 1992).

The possible association between hydatiform mole and preeclampsia supports the theory of genetic conflict in pregnancy. In the case of a hydatiform mole, there is an excessive placental proliferation without associated fetal tissues; significantly there are two paternal genomes but no maternal genomes. A hydatiform mole is characterized by high levels of HCG. This fact suggests that, in the case of preeclampsia, it is probably via HCG that the placenta manipulates maternal physiology in order to maintain high levels of DHA available.

Even the high level of DHA in preeclampsia has been considered as enigmatic. The authors of a Dutch study were intrigued at such a point that they raised the possibility that fish oil supplementation may be contraindicated in pregnancy (Al et al. 1995). There is no enigma if the focus is on the collapse of the parent molecule EPA and if the link between preeclampsia and brain development is understood.

It is well known that women with preeclampsia are at risk of having low-birth-weight babies. They are also at risk of having large babies. A study looking at 97,270 births in 35 hospitals in Alberta, Canada, revealed that, after adjustment for gestational age and other factors, the rates of large-for-gestational-age babies were twice as high among women with preeclampsia (4.7%) and gestational hypertension (4.5%) than among women with normal blood pressure (2.2%). The authors conclude that their findings cannot be reconciled with the currently held pathophysiologic notions. In our view it is possible to explain that when the baby is large the demand in nutrients is high and the risk of maternal fetal conflict is increased. It is also possible to understand that when the conflict lasts long enough the baby is at risk of being small-for-dates (Xiong et al. 2000).

As a student of human nature, I give a great importance to the issue of maternal fetal conflicts in our species and, by comparison, in other species of mammals.


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Michel Odent, MD, has been influencing the history of childbirth and health research for several decades. As a practitioner he developed the maternity unit at Pithiviers Hospital in France (1962–1985). With six midwives, he was in charge of approximately one thousand births a year and achieved excellent statistics with low rates of intervention. Odent is familiarly known as the obstetrician who introduced the concept of birthing pools and home-like birthing rooms. He later founded the Primal Health Research Center in England. After his hospital career, Odent practiced homebirths. His approach to childbirth has been featured in eminent medical journals such as The Lancet and in TV documentaries such as the BBC film, Birth Reborn. Odent is a contributing editor to Midwifery Today magazine.

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