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The objective of this work was to investigate the emergence of intrapair stimulation between twin fetuses and the presence of possible changes in types and percentage of evoked patterns with advancing gestational age. The existence of intrapair stimulation would indicate the functioning of fetal tactile and proprioceptive sensibility. This was studied from video recordings of 30 min ultrasonographic observations of 8 twin pregnancies at 8, 9 and 10 weeks gestational age, of 20 twin pregnancies at 11, 12 and 13 weeks and of 20 twin pregnancies studied with 60 min observations at 15-16, 18-19 and 21-22 weeks. All age groups were subdivided in Monochorionic (Mc) and Dichorionic (Dc) pregnancies. Intrapair stimulation before 11 weeks gestational age is an exceptional event. Due to greater spatial contiguity and thinness of the membrane dividing the two amniotic sacs in Mc pregnancies, it was noted only in these. From 12 weeks onwards, evoked movements began to be observed in Dc pregnancies as well. After the 15th week, intrapair stimulation is a constant and increasing feature of all twin gestations. Movements vary from generalized bodily activity to being progressively localized. No specific evoked movement patterns were observed.

Objective: To construct reference ranges for fetal pH, oxygen pressure (PO2), and hematologic and biochemical blood constituents, which can be used to analyze changes with gestation and differences with maternal values, thus elucidating some aspects of fetal biology and the effects of the maternal and placental environments., Methods: We assayed venous pH, PO2, hematocrit, glucose, uric acid, urea, creatinine, total protein, total and direct bilirubin, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyltransferase, alkaline phosphatase, lactic dehydrogenase, amylase, pseudocholinesterase, creatine kinase, triglycerides, and cholesterol concentrations in 157 fetuses and 134 mothers who underwent fetal blood sampling from 18 to 37 weeks' gestation. None of the fetuses was infected or had chromosomal, hematologic, or hormonal abnormalities., Results: All the variables analyzed were similar in fetuses sampled at the placental cord insertion (n = 125) or at the intrahepatic vein (n = 32). Maternal and fetal concentrations of glucose (r = 0.79, P < .001), urea (r = 0.96, P < .001), creatinine (r = 0.83, P < .001), and uric acid (r = 0.94, P < .001) correlated significantly, and their differences exhibited significant changes: the maternal-fetal differences of glucose and urea increased, whereas those of uric acid and creatinine decreased with advancing gestation. Fetal pH and PO2 decreased with gestational age, whereas hematocrit increased, similar to what has been described previously. All of the other variables, with the exception of amylase and cholesterol, changed significantly during the investigated period of pregnancy. Gestational age explained at least 40% of the variance in values of fetal total protein, pseudocholinesterase, alanine aminotransferase, creatine kinase, and triglycerides, but only 3-25% of the variation in the remainder. Most enzymes were higher in the fetus than in the maternal circulation, and all except alkaline phosphatase increased with gestational age. The maternal-fetal glucose difference correlated significantly with hematocrit, pH, and PO2, independent of gestational age and independent of each other., Conclusion: With the exception of aspartate aminotransferase, all of the analyzed fetal variables were different from the maternal values, and most changed with gestational age. The mechanisms leading to these fetal specificities remain mostly uncertain, but the provision of reference ranges for several blood constituents may be useful in the differential diagnosis of fetal disease.