The Evolution of the Primal Health Research Database

I started to compile studies in the framework of Primal Health Research at the time of the publication of “Primal Health” (1986). All these studies, published in authoritative medical and scientific journals, explore correlations between what happens during the primal period (fetal life, perinatal period, and year following birth) and what happens later on in terms of health and personality traits. With the development of information technology, this collection of studies eventually became a database everybody can explore on the web ( and

Originally, I often presented our database as a tool to train ourselves to think long-term. Until now, the practices of obstetrics and midwifery have been evaluated through short term criteria (in particular perinatal mortality/morbidity rates and maternal mortality/morbidity rates). In the age of simplified fast techniques of cesarean sections with minimal blood loss and regional anaesthesia, it is becoming justified to offer this operation to all pregnant women …if the only list of conventional criteria is taken into account. In such a context, scientific advances (and intuitive knowledge) suggest the need for long-term criteria. There are also reasons to enlarge our horizon by thinking in terms of civilization, a specifically human dimension: our database can also be presented as a tool to become familiar with this collective dimension, since researchers ignore anecdotes and need huge numbers to detect statistically significant effects of early experiences. A typical example, among many others, is provided by a study of the risk factors for autism. The researchers had at their disposal the birth records of the whole Swedish population born during a period of twenty years; they also had at their disposal the medical files of all Swedish subjects who had been diagnosed autistic with strict criteria, plus five controls for each of them. With such a material they could detect statistically significant risk factors in the perinatal period. (see entry 0396 via keyword “autism”)

The advent of epigenetics suddenly gave the Primal Health Research Database a new function. This emerging discipline is based on the concept of gene expression. Some genes may be allocated a kind of label (an “epigenetic marker”) that makes them silent. This marker can be a DNA methylation; it can also be a change in the nuclear protein content, such as modifications to histones. This phenomenon of gene expression is influenced by environmental factors, particularly during the primal period. An overview of the database suggests the importance of the concept of timing: the nature of an environmental factor often appears less important than the time of exposure to this environmental factor. For example, when exploring our database from a keyword related to a metabolic type (such as “diabetes type 2” or “obesity”), fetal life usually appears as a critical period for gene-environment interaction. If the keyword is related to the capacity to love it appears that the period surrounding birth is critical. Our database has become a unique tool to provide some clues about the critical periods regarding the genesis of diseases and personality traits. From a practical perspective it is often more important to identify such critical periods than to identify the genes involved or the comparative parts of genetic factors and environmental factors.

The paramount importance of the concept of “timing” explains my interest for pathological conditions that share the same critical period for gene-environment interaction. It appears that when two diseases share the same critical period, other similarities are probable from other perspectives, such as clinical and physiopathological perspectives. This is how I have explored the multiple links between autism and anorexia nervosa.1 Can the Primal Health Research Database inspire new ways to classify diseases?

In the age of epigenetics, we have been encouraged to pay a renewed attention to studies exploring the transgenerational effects of what happens during the primal period. It appears today that the epigenetic markers (the “epigenome”) may be to a certain extent transmitted to the following generation. Understanding how acquired traits can be transmitted to the following generation is an important step in our understanding of the transformation of species and their adaptation to environmental factors. The keyword “transgenerational” leads in particular to Dutch studies about the effects on the second generation of exposure during fetal life to the famine of winter 1944-1945 (see entries 0753, 0756). It also leads to a unique Swedish study in the isolated rural area of Overkalix (entry 0796) and to a study of the effects of exposure during fetal life to diethylstilbestrol , the synthetic estrogens given to pregnant women in the middle of the twentieth century (entry 0796).

The concept of heritability of epigenetic markers will justify an increased number of animal experiments, particularly among mammals with a short lifespan. This is why we have decided to stop feeding the keyword “experimental primal health research”, in order to remain inside the limits of a specialised branch of human epidemiology.

In general, it appears that the functions of the Primal Health Research Database are constantly renewed under the influence of a grand diversity of emerging disciplines. Many correlations established by epidemiologists can inspire plausible new interpretations. For example, according to an American study, caesarean birth appears as a risk factor for obesity in childhood (entry 0829 via keyword “obesity in childhood”). At the same time we have learned that the gut flora of obese people is different from the gut flora of lean people2, and we start realizing that the way the human gut flora is established in the perinatal period cannot be the same after a birth via the bacteriologically rich perineal zone compared with a birth by caesarean. It is also probable that in the near future studies included in our database will inspire interpretations based on explorations of the expression of Mitochondrial Uncoupling Protein2 (UCP2) in hippocampal neurons. These studies confirm the positive effects of stress in the perinatal period on brain development.3 They might offer new interpretations to established correlations, such as those among conscripts. According to one of them, there is a correlation between forceps delivery and comparatively high Intellectual Quotient (IQ), while another one found a comparatively high IQ among conscripts born by vaginal route after breech presentation compared with those born by caesarean. (See entries 0001 and 0002 via keyword “forceps”, and entry 0530 via keyword “breech presentation”).

The vitality of the Primal Health Research Database is an effect of its constant interaction with a great diversity of emerging scientific perspectives.

Michel Odent
August 2012


  1. - Odent M. Autism and Anorexia Nervosa: two facets of the same disease? Medical Hypotheses 2010. doi:10.1016/j.mehy.2010.01.039 .
  2. - Turnbaugh PJ, Ley RE, Mahowald MA, etc An obesity-associated gut microbiome with increased capacity for energy harvest.. Nature 2006. Dec 21; 444(7122): 1027-31.
  3. - Simon-Areces J, Dietrich MO, Hermes G, et al. UCP2 Induced by Natural Birth Regulates Neuronal Differenciation of the Hippocampus and Related Adult Behavior. PLoS ONE, 2012; 7 (8): e42911 DOI: 10.1371.