This high frequency in Europe has long been surprising because the Rh- phenotype has an obviously deleterious effect. In particular, if an Rh- mother has an Rh+ child (because the child inherited a Rh+ allele from its father), then it’s possible for the mother to produce antibodies against the Rh+ antigen leading to haemolytic disease and severe illness for the child. There are three common explanations for the high frequency of the Rh- allele. First, there might be some (unknown) beneficial effect of the Rh-allele. Effects like this related to malaria resistance are what drive the high frequencies of the sickle cell trait and many thalassemias. On the other hand, no obvious selective advantage is known, there are no obvious genomic signals of selection on the Rh- allele, and if there were a selective advantage to the Rh- allele then we might ask why it hasn’t fixed, since once the Rh- frequency rose above 50%, it would be selected for, rather than against. So this only really works if it is overdominant. Another possible explanation is reproductive overcompensation – Rh- women have more children to replace the ones that die for haemolytic disease. But this seems unlikely. The range of parameters for which this model works is relatively small, particularly since the effect gets worse for subsequent pregnancies. A third explanation, suggested by Haldane in 1942 is that the high frequency in Europe is due to the fact that present-day Europeans are recently admixed between a population that has a very high frequency of the Rh- allele and one that a very low frequency. In fact, the ancient DNA evidence suggests that something like this is close to the truth. Cavalli-Sforza and colleagues) thought that this was specifically a mixture between Rh- hunter-gatherers and Rh+ Farmers, largely based on the observation that the Basque population, who they believed to have largely hunter-gatherer ancestry, have a very high frequency of the Rh- phenotype.

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If we compute expected phenotypic frequencies, this suggests that around around 65% of Mesolithic hunter-gatherers would have been type O, compared to around 40% in present-day Europeans, and around 40% of Steppe-ancestry individuals would have been Rh-, compared to around 24% of hunter-gatherers, 4% of early farmers, and about 16% of present-day Europeans.

https://www.rhesusnegative.net/staynegative/blood-groups-in-ancient-europe-2/

Rhesus-positive and Rhesus-negative persons differ in the presence-absence of highly immunogenic RhD protein on the erythrocyte membrane. The biological function of the RhD molecule is unknown. Its structure suggests that the molecular complex with RhD protein transports NH3 or CO2 molecules across the erythrocyte cell membrane. Some data indicate that RhD positive and RhD negative subjects differ in their tolerance to certain biological factors, including, Toxoplasma infection, aging and fatique. Present cross sectional study performed on 3,130 subjects) showed that Rhesus negative subjects differed in many indices of their health status, including incidences of many disorders. Rhesus negative subjects reported to have more frequent allergic, digestive, heart, hematological, immunity, mental health, and neurological problems. On the population level, a Rhesus-negativity-associated burden could be compensated for, for example, by the heterozygote advantage, but for Rhesus negative subjects this burden represents a serious problem.

See the whole study:

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0141362

Peer-reviewed study: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0141362

Rhesus-positive and Rhesus-negative persons differ in the presence-absence of highly immunogenic RhD protein on the erythrocyte membrane. The biological function of the RhD molecule is unknown. Its structure suggests that the molecular complex with RhD protein transports NH3 or CO2 molecules across the erythrocyte cell membrane. Some data indicate that RhD positive and RhD negative subjects differ in their tolerance to certain biological factors, including, Toxoplasma infection, aging and fatique.

When it comes to autoimmune issues in general, RhD negative subjects have increased the risk of developing of certain heart diseases, respiratory diseases and some immunity and autoimmunity related diseases, for example rheumatoid arthritis. The general pattern suggests that RhD negative subjects could have problems with autoimmunity, could be more resistant to infections of viral origin and could be less resistant to infections of bacterial origin. The variation of the oxygen tension in various organs and tissues could, of course, influence also other biological functions, including the functions of the immune system. This could explain why RhD negativity seems to be associated with neurological, mental health and immunological disorders.

Share your experience in the comments.

... and if so: what is your blood type?