Further, in RA patients, symptoms tend to only show improvement during pregnancy, but exacerbation of symptoms postpartum 100. In 2011, the flu vaccine was included in the National Immunization Schedule (NIS) as mandatory and free of charge, with the aim of decreasing complications and death due to influenza in the at-risk population in Argentina. Fetal cells enter the maternal tissues during pregnancy, possibly enhancing susceptibility to some diseases such as autoimmune diseases and cancer. Together these findings suggest that fetal microchimeric cells may play a role in breast physiology and milk supply, but the effects on maternal health are not yet clear.

De statistiek van de moedersterfte wordt opgesteld op basis van de gegevensbank van de doodsoorzaken. In a cross-sectional population-based serosurveillance study conducted in 2006-07, from a randomly selected age-stratified sample of 7,903 persons, serum IgG-Ptx concentrations were analyzed using a fluorescent bead-based multiplex immuno assay. Fetal IgA showed a slow linear rise with fetal levels at term remaining approximately 1,000 times lower than the concentration in the maternal circulation. This means that there can be conflict over maternal milk supply, with offspring interests favoring higher milk supply than what is optimal for the mother 5.

Fetal cells with stem‐like properties located in the mammary gland could be responding to the same maternal signals.

Both, IgG and IgA throughout pregnancy decreased to a level of 60-70% (37-41 WG) of the initial concentration in early pregnancy. Fetal cells in the mouse maternal brain have been found to be able to integrate into to maternal brain circuitry and express appropriate immunocytochemical markers for brain tissue 47. In 2010, due to a pertussis outbreak and neonatal deaths, the California Department of Health recommended that the tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine (Tdap) be administered during pregnancy.However, a murine model of breast cancer found that high‐grade tumors harbored significantly more fetal cells than low‐grade tumors 58 and fetal cells have also been found in the tumor stroma of human females 59. Given the recent increases in the rate of pertussis infection and morbidity and mortality in neonates, these early data provide initial evidence for evaluating the safety of the vaccine in pregnancy for health professionals and the public and can help to inform vaccination policy making.

Humans have very high levels of postpartum parental investment compared to other species, and have clear adaptations for parental investment which include lactation but also extended food sharing 32 both of which are facilitated by emotional attachment and bonding 33. Microchimerism is common in humans and has been found across eutherian mammals of all placental types. Similar to fetal trophoblast cells invading maternal endometrium during placentation, fetal cells circulating in the maternal body may be able to colonize other tissues and persist in the maternal body after parturition.Presence of fetal cells in the thyroid might also contribute to thyroid cancer risk or susceptibility to other thyroid diseases if these cells are proliferating or producing factors that may induce abnormal thyroid physiology. This conflict is instantiated through a number of mechanisms including genomic imprinting and placental hormone production 3, 5. Pasgeborenen en jonge, nog niet of onvoldoende gevaccineerde zuigelingen vormen de belangrijkste risicogroep voor het krijgen van een ernstige kinkhoestinfectie. Waning of vaccine-induced immunity has been cited as one of the reasons for the observed epidemiologic trend. In patients with preexisting autoimmune disease, a family history of autoimmune disease, and no susceptibility to autoimmune disease, measure abundance of fetal cells and measure autoimmune disease symptoms, C‐reactive protein levels, and abundance of T regulatory cells pre‐partum, each trimester, and postpartum.