[Does the decreasing rate of neonatal mortality increase severe neonatal neurosensory morbidity?]

To investigate relation between the mortality and the incidence of serious neonatal neurosensoric morbidity in very low birth weight newborns (VLBWN, birth weigh < or = 1499 g) during the three periods as defined by different quality of the parinatal and neonatal care.

Retrospective analysis.

Perinatal center of the General Faculty Hospital. 1st Medical Faculty Charles University, Prague.

All live-born VLBWN in 1987-2001 were divided according to their birth-date to three five-year periods characterized by different quality of the perinatal and neonatal care. Ist period 1987-1991: the presurfactant area with no standard use of antenatal steroids and without defined border of the fetus viability; IInd period 1992-1996: the transient aera; IIIrd period 1997-2001: the surfactant aera with standard use of the antenatal steroids, and defined border of the fetus viability. VLBWN were divided according to birth weight to three subgroups (p. h. < 750 g, p. h. = 750-999 g, p. h. = 1000-1499 g). Mortality was defined by a death in our department until the discharge. VLBW newborns classified as newborns with serious neonatal neurosensoric morbidity (NNsM) had to have one of the following diagnoses at least: severe intraventricular haemorrhage (IVH gr. 3-4), posthemorhagic hydrocephaly (PHH), cystic periventricular leukomalacia (cPVL), meningitis, ventriculitis, encephalitis (M/E), retinopathy of prematurity > or = stage III (ROP > or = III st.). The chi 2 test was used for statistic evaluation.

There were 873 VLBWN born and 208 of them died in the whole period (1987-2001). Mortality decreased in 5 year periods gradually: 1st period 111/226 (49%); IInd period 55/217 (25%); IIIrd period 42/430 (10%). The decrease of mortality was significant in all weight categories (p < 0.001). The incidence of NNsM was evaluated in 612 newborns and was similar in all periods regarding weight subcategories < 1000 g, but decreased significantly in the weight category 1000-1499 g (14/215 (6%) vs 13/73 (18%), p < 0.01).

Improvement in survival of extremely low birth-weight infants did not increase the incidence of serious neurosensoric morbidity and evenmore NNsM was reduced in haevier very premature newborns during the nineties.