pituitrin and Fetal-Growth-Retardation

The occurrence of electrolyte disorders as hypocalcemia and/or hyponatremia is an uncommon event in preeclampsia, which can be the sign of serious situation, with potentially unfavourable consequences for the mother and her fœtus. Hyponatremia in the setting of preeclampsia is an indicator of severity, and requires the understanding of the etiologic mechanisms to initiate an appropriate treatment. Indeed the often-considered fluid restriction is rarely a treatment option for pregnant women. Hypocalcemia is a complication that must be monitored when a treatment with high doses of intravenous magnesium sulphate is introduced. In this context, hypocalcemia must be sought, with the exclusion of other etiologies as vitamin D deficiency, hypoparathyroidism or renal and extrarenal loss of calcium. A replacement therapy, intravenous or oral according to circumstances, should be considered in case of severe or symptomatic hypocalcemia.

Topics: Adult; Aldosterone; Antihypertensive Agents; Capillary Leak Syndrome; Cesarean Section; Emergencies; Female; Fertilization in Vitro; Fetal Growth Retardation; Humans; Hypocalcemia; Hyponatremia; Infant, Newborn; Infusions, Intravenous; Labetalol; Magnesium Sulfate; Male; Pre-Eclampsia; Pregnancy; Pressoreceptors; Renin-Angiotensin System; Vasopressins

Heat-stressed pregnant ewes deliver intrauterine growth-retarded lambs. Selected maternal and fetal changes were investigated during acute heat stress in order to elucidate the mechanism for this growth retardation. Uterine blood flow decreased 20 to 30% in pregnant ewes during 1 degree C increases in core temperature. The decreases were accompanied by 60 and 100% increases in serum oxytocin and antidiuretic hormone, respectively. These effects were mimicked by salt loading or injections of antidiuretic hormone or oxytocin, suggesting a role for either or both hormones in regulating uterine blood flow during pregnancy. Chronically heat-stressed pregnant ewes were delivered by Caesarean section. Their fetuses were approximately 20% smaller than thermoneutral controls. Within each pair of heat-stressed twins, one fetus weighted one-third less than its litter mate. No difference in weights were observed within the control twins. The livers and brains of the heat-stressed fetuses were disproportionate in size. The livers from the small heat-stressed twins contained only one-half the protein of the controls and one-fourth the protein of their litter mates. Muscle protein was decreased in the heat-stressed fetuses, and liver and muscle glycogen were elevated as were liver arginase, glutamate-pyruvate transaminase and muscle creatinine. These results are consistent with the following hypothesis: heat stress stimulates the release of maternal antidiuretic hormone or oxytocin, which reduces uterine blood flow and causes a shift in fetal metabolism from anabolic to catabolic pathways; one fetus of heat-stressed twins is more severely affected than its litter mate.

Topics: Animals; Body Weight; Female; Fetal Growth Retardation; Hot Temperature; Litter Size; Myocardium; Organ Size; Oxytocin; Pregnancy; Pregnancy Complications; Regional Blood Flow; Sheep; Sheep Diseases; Stress, Physiological; Uterus; Vasopressins

Oxytocin and vasopressin are hormones having a number of peripheral and (more recently detected) central activities. The two peptides are found to be present in both human amniotic fluid and in that of rats. The origin of these substances was studied in combined clinical and experimental investigations, as were also the relationships of these compounds with intra-uterine growth and the process of labour. Oxytocin was not found to originate from the foetal brain, the foetal adrenals being suggested as a possible alternative source. There was found to be a positive correlation between amniotic oxytocin and measures of the foetal brain, amniotic vasopressin possibly reflecting a poor condition of the foetus (stress?).

Topics: Amniotic Fluid; Animals; Female; Fetal Growth Retardation; Humans; Labor, Obstetric; Maternal-Fetal Exchange; Oxytocin; Physiology, Comparative; Pregnancy; Pregnancy, Animal; Rats; Vasopressins

Cord plasma vasopressin concentration, determined by radioimmunoassay, was higher in arterial than in venous blood in 122 (84%) infants; the highest vasopressin values were recorded in 21 acidotic infants (mean cord pH, 7.13) delivered per vaginam and the lowest values in 50 infants delivered by cesarean section. Cord vasopressin levels were not elevated in infants delivered by cesarean section because of obstructed labor. There was a lack of correlation between vasopressin levels and the length of labor or cervical dilatation; a significant correlation was found between cord arterial vasopressin values and pH. Low vasopressin values were recorded in a group of 22 healthy infants (mean cord pH, 7.29) delivered by low forceps operation.

Topics: Abruptio Placentae; Adolescent; Adult; Cesarean Section; Delivery, Obstetric; Female; Fetal Growth Retardation; Humans; Hydrogen-Ion Concentration; Infant, Newborn; Infant, Premature; Labor, Induced; Obstetrical Forceps; Pre-Eclampsia; Pregnancy; Pregnancy Complications; Radioimmunoassay; Umbilical Cord; Vasopressins