Influence of blood pressure changes with and without proteinuria upon outcome of pregnancy.

A prospective study of 10,074 white gravidas and 2,880 black gravidas carried out during the years 1959 to 1967 has been analyzed with respect to the impact of elevated blood pressures and/or proteinuria upon pregnancy outcome. Edema was not considered because no evidence is available to indicate that its occurrence increases risk. The mean arterial pressure exhibited during the fifth and sixth months of pregnancy was found to be of significance, as well as the absolute levels of blood pressure attained prior to labor and delivery. The degree of rise in blood pressure was not of importance in itself. However, categories with significant proteinuria had greater increases in mean arterial pressure than did comparable categories without it. Significant proteinuria alone but especially with hypertension was also detrimental to pregnancy outcome. Eight categories incorporating early and late hypertension with and without proteinuria were created, and these were given descriptive diagnostic labels. Only "gestational hypertension," as defined, proved to be essentially devoid of risk to the fetus. In all other non-normotensive categories there was an increase in the stillbirth rate, the perinatal mortality rate, the frequency of intrauterine growth retardation, and neonatal morbidity. In every category, each of these untoward events was greater in black than in white gravidas, and a higher percentage of blacks was noted in each of the hypertensive categories. It is believed that hypertension, significant proteinuria, or both are associated with decreased uteroplacental blood flow which is the common denominator for all of these deleterious effects. The study suggests that "gestational hypertension" occurring late but without proteinuria may or may not represent an early stage of "pre-eclampsia" but does not, at least, place the infant at any substantially increased risk.