The relationship between maternal hypertensive disease of pregnancy and the incidence of idiopathic respiratory distress syndrome.

The relationship between maternal hypertensive disease of pregnancy (HDOP) and idiopathic respiratory distress syndrome (IRDS) was analyzed in 2,105 premature infants weighing between 1,000 and 2,199 gm and born between January 1968 and December 1975 at the Kings County Hospital Center and State University Hospital. HDOP was diagnosed in 250 mothers of 2,105 infants studied. The incidence of IRDS (15.2%) in the HDOP group was significantly lower than the 29.9% in the non-HDOP group (P less than .001). In infants whose gestational age was 32 weeks or less, the incidence of IRDS was 26.1% in the HDOP group and 40.8% in the non-HDOP group (P less than .01). In infants whose gestational age was 33 weeks or more, the incidence (9.3%) in the HDOP group was significantly lower than the 18.4% in the non-HDOP group (P less than .005). The low incidence of IRDS in the HDOP group remained even after eliminating infants with known predisposing and protecting factors from the development of IRDS. The incidence of IRDS was inversely related to the severity of maternal toxemia. The total mortality and mortality with IRDS were not significantly different in both HDOP and non-HDOP groups. When the infants did not develop IRDS, the mortality rate in the HDOP group was significantly higher than that in the non-HDOP group especially in the lower gestational age group. These data suggest that chronic stress accelerates fetal lung maturation and severe chronic stress is even more effective in accelerating fetal lung maturation. When maternal toxemia was severe enough to accelerate the fetal lung maturation, the mortality rate of the infants without IRDS increased.