Neonatal and maternal platelet cytosolic calcium in normotensive and hypertensive pregnancies.

A prospective study investigated platelet cytosolic calcium in non-pregnant volunteers (n = 30) and samples from the umbilical veins of babies from both normotensive (n = 18) and hypertensive (n = 15) primigravidae, and their mothers. There was no significant difference between the neonatal umbilical venous platelet cytosolic calcium concentration (p[Ca2+]i) in babies born to normotensive primigravidae or to those whose pregnancies were complicated by gestational hypertension (88 x 9 (SE) 2 x 5) in normotensive primagravidae, 80 x 6 (2 x 8) in pregnancy induced hypertension without proteinuria, and 89 x 3 (3 x 2) nmol/l in pre-eclampsia. There was also no significant difference in the p[Ca2+]i from the umbilical veins of the pregnancies studied and those of non-pregnant female volunteers in the follicular phase of their menstrual cycle. This was despite a gradual and significant rise in p[Ca2+]i with increasing severity of disease in the mothers of the babies studied (119 x 9 (4 x 1) in normotensive primagravidae, 130 x 8 (7 x 3) in pregnancy induced hypertension without proteinuria, and 148 x 2 (4 x 5 ) nmol/l in pre-eclampsia). The mean maternal p[Ca2+]i in the three samples returned to concentrations comparable with those in non-pregnant subjects by 12 weeks after birth. These data demonstrate no significant difference between the mean p[Ca2+]i in non-pregnant women and those obtained from the umbilical venous blood of normotensive or hypertensive primigravidae. They suggest that the functional hypoactivity of neonatal platelets is probably not secondary to a decrease in basal p[Ca2+]i. They also suggest that the progressively raised p[Ca2+]i in normal and hypertensive pregnancies might be due to a pregnancy specific factor that does not cross the placenta,