Adrenomedullin in perinatal medicine

This review will consider whether adrenomedullin (AM) plays a role in the different aspects of perinatal medicine: contributing to maternal systemic vasodilatation during pregnancy, regulating uterine and placental blood flow, being involved in the process of implantation and participating in uterine quiescence prior to parturition. In addition, this will also consider whether a modification of AM secretion contributes to some pathological conditions in pregnancy such as preeclampsia and impairment of fetal growth. The biosynthesis of AM increases in gravid rats and in pregnant women, and the placenta represents an important site of AM production during pregnancy. Both the peptide and its receptors have been found in the uterus, placenta, fetal membranes and cord vessels, and fetal membranes and placental tissues in culture secrete AM. AM contributes to maternal systemic vasodilatation, the placental vessels are relaxed by AM in a dose-dependent manner and AM is expressed in the fetoplacental and umbilical vascular endothelium where basal production of AM contributes to low fetoplacental vascular resistances. Controversy exists over the status of circulating and placental AM in preeclampsia and of the relative contribution of AM to impaired fetoplacental circulation and fetal growth. Moreover, the uterus expresses AM mRNA and exogenous AM relaxes the myometrium in a dose-dependent manner; however, clinical studies have shown that AM does not decrease before the onset of parturition. Rather, AM secretion increases during spontaneous labor and in preterm delivery.     

Specialized perinatal care: impact on perinatal mortality.

A neonatal intensive care unit was established at one hospital in 1972 when the neonatal mortality was 7.6 and the perinatal mortality 20.9 per 1000 deliveries. In 1973, with full operation of that unit and partial introduction of a high-risk pregnancy unit for fetal monitoring, the rates decreased to 6.4 and 14.9, respectively. With full operation of both units the rates decreased further, to 3.4 and 9.0 in 1974 and 3.8 and 8.9 in 1975. The frequency of cesarean section was 10.1% in 1972-73 and 11.6% in 1974-75. It is concluded that the centralization of obstetric and neonatal care, together with the development of qualified medical and nursing teams, had a major impact in reducing perinatal mortality, and that the frequency of cesarean section was not affected by the introduction of fetal monitoring, although the indications for this precedure became more specific.     

Practical management of perinatal death.

After the loss of a newborn baby the parents are usually too shocked and unfamiliar with the complicated administration procedures to cope with the registration of death and burial (or cremation). The medical and nursing staff also tend to be unfamiliar with the procedures. Some of these can be streamlined, thus reducing the stress caused to parents. By giving positive instruction the staff will in their turn be able to improve their care of the bereaved parents.     

The Scottish perinatal mortality survey.

Perinatal deaths in single births that occurred in Scotland during 1977 were investigated by case-record analysis. Causes of death were divided into nine categories, an extended version of the Aberdeen classification being used. Out of 1012 single perinatal deaths, 265 were due to fetal abnormality, which in 140 cases was malformation of the central nervous system. Of the 747 normally formed infants, 446 weighed 1500 g or more, of whom 82 died intra partum and 154 were born alive. The largest single cause of death was low birth weight in normally formed babies whose mothers had no complications of pregnancy (302 cases). Of these babies, 103 (34%) were growth-retarded. Rhesus incompatibility (16 deaths) and maternal diabetes (seven deaths) were not major causes of perinatal loss. These results were thought to be valuable in illustrating the main causes of perinatal mortality and directing attention to important issues. Hence a modified version of the study is being continued to see whether yearly audit by regional assessors is a feasible and practical way of monitoring trends in perinatal mortality.