Blood maternal placental

Kuhnert PM, Kuhnert BR, Erhard P. 1981. Comparison of mercury levels in maternal blood, fetal cord blood and placental tissues. Am J Obstet Gynecol 133 209-213. 

Effect of Varying Maternal Placental Blood Flow. Figure 11 shows the dependence of end-capillary p02 on maternal placental flow, Qm. At large flow rates the p02 of end-capillary blood approaches that of the maternal artery. At lower rates of flow the equilibrated po2 value decreases because less 02 is available for exchange. The rate of 02 transfer follows a trend similar to that of end-capillary po2, except that increases in above 300-400 ml/min result in little additional 02 transfer because the rise in mean maternal p02 adds little 02 content to the flat part of the fetal oxyhemoglobin saturation curve. 

Cyclic Changes on Maternal Velocity. During labor the contractions of the uterus create a rhythmical increase and a decrease of the amniotic pressure. Although no specifically determined relationship between amniotic pressure and maternal placental blood flow rate has been shown, it is well known that the maternal blood flow rate is retarded in... 

Cadmium in umbilical cord blood and placental tissue was determined for 31 samples collected at the Gynecology Maternity Ward in Kikinda Hospital, and 30 samples collected at the Gynecology Maternity Clinic in Novi Sad, in the period 1996-1997. The samples of hepatizated blood and placental tissue were broken down by nitrous acid using a wet process, the fats were extracted using diethyl ether, and the cadmium concentration was determined by atomic absorption spectrophotometry on a graphite furnace (Vather, 1982 Stoeppler, 1983 Beauty, 1988). 

Pinheiro FS, Jorge SM, Martinez FE. 1992. Plasma zinc and copper levels in maternal, placental intervillous space and cord blood. Nutrition Research 12(3) 367-373. 

Hauser, G., and Junker, G. Comparison of Chlorinated Hydrocarbon Pesticides in Maternal Blood and Placental Tissues Environ. Res. 2(4) 247-255 (1969) CA 71 111829n... 

Table 1 includes neonatal outcome variables reported to be significantly related to low-level maternal, placental, cord, or very early infancy PbB in one or more studies. Case reports and some older studies that include additional adverse outcomes, usually as a result of high-level exposure (Rom, 1976), have been excluded. To save space. Table I excludes reports of assessed outcome measures not significantly related to PbB in any study in the review. These variables are pre-eclampsia, spontaneous abortion, foetal distress, ponderal index, intrauterine growth retardation, meconium staining, Apgar scores, jaundice, blood type, sex of infant and most scales of the Brazelton Newborn Assessment Scale. 

Placental transfer of trichloroethylene occurs in animals. Trichloroethylene inhaled by pregnant sheep and goats, at levels used to induce analgesia and anesthesia, is rapidly distributed into the fetal circulation, with peak levels occurring approximately 40-50 minutes after maternal exposure (Helliwell and Hutton 1950). The concentration of trichloroethylene in umbilical vein blood was comparable to that found in the maternal carotid artery. 

Lauwerys R, Buchet J-P, Roels HA, et al. 1978. Placental transfer of lead, mercury, cadmium, and carbon monoxide in women I. Comparison of the frequency distributions of the biological indices in maternal and umbilical cord blood. Environ Res 15 278-289. 

The interaction between the adrenal cortex of the foetus and the placenta in production of steroid hormones is complex. In outline, the placenta produces progesterone from cholesterol (which is available from the maternal blood) whereas the foetal adrenal cortex produces corticosteroids and androgens from the progesterone produced in the placenta. The placenta then converts some of these androgens into oestrogens. The interplay between the placenta and the foetal adrenal cortex is acknowledged by the use of the term foeto-placental unit to describe steroido-... 

Fluoride readily crosses the placenta and is found in foetal and placental tissue. There appears to be a direct relationship between fluoride levels in maternal blood and cord blood [79-82]. At relatively low maternal blood levels, the cord blood levels were at least 60% of that of maternal blood [80,82]. Although cord fluoride levels were typically lower than maternal levels, one study found no statistical difference between maternal and newborn (1-day-old) serum fluoride levels, suggesting that cord serum fluoride levels do not reflect foetal fluoride status [83]. There is also evidence, however, that the placenta can accumulate fluoride, possibly playing a regulative role that helps protect the foetus from excessive amounts of fluoride, when maternal fluoride intake is high [79,84]. 

The placental membranes are also lipoidal in nature and lipophilic drugs (also nonlipid soluble drugs to some extent) can easily cross the placental barrier. It is a contact between the foetal blood and the maternal blood. Drugs are transferred through this barrier by simple diffusion method, once across this, drug molecules circulate in the foetal blood before diffusing back. 

Placental transfer of di(2-ethylhexyl) phthalate has been observed following intra-peritoneal administration of di(2-ethylhexyl) [car6o y/- C]phthalate on gestational day 5 or 10 in rats (Singh et al, 1975). The dams were killed at 24-h intervals starting on days 8 and 11 until day 20 of gestation. Radioactivity was detected in fetal tissues, amniotic fluid and placenta at all time points. The radioactivity peaked at 48 h and declined rapidly thereafter. The concentration was less than that in maternal blood and less than 1% of the administered dose. 

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