Bacterial or viral infection of the mother during the course of pregnancy can cross the placenta and actively infect the fetus. However, especially for bacteria, it is more common for mothers to experience an infection that can be treated without overt fetal infection.
Which bacteria can cross the placental barrier?
Maternal infections caused by most organisms which can cross the placenta (including rubella, mumps, poliomyelitis, smallpox, rubeola, syphilis, malaria, toxoplasmosis, and infections caused by S typhosa, V fetus, L monocytogenes, cytomegalovirus, and herpes simplex virus) may result in abortion or stillbirth.
What can pass through placental barriers?
Lead, cobalt, arsenic and selenium appear to pass the placental barrier by a diffusion mechanism. It was also found that the mercury levels in cord blood were almost double those of the mother, suggesting that the foetus may act as a filter for the maternal mercury levels during pregnancy.
What substances can not cross placental barrier?
Most drugs with MW < 500 Da cross the placenta, and most drugs with MW > 1000 Da do not cross the placenta (ex. heparin, protamine, insulin). Neither succinylcholine (highly ionized) or non-depolarizing NMBDs (high molecular weights) cross the placenta.
Does the placenta allows passage of bacteria and virus?
During pregnancy, viruses and bacteria may be transmitted to the developing placenta via ascending infections, because retrograde transmission from decidual cells through cell columns to anchoring and floating villi is possible.
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