THE COMBINED EFFECT OF BIRTH WEIGHT AND LENGTH OF GESTATION ON NEONATAL MORTALITY AMONG SINGLE PREMATURE BIRTHS

The combined effect of birth weight and length of gestation on mortality during the neonatal period was studied, using information obtained from birth and death certificates filed with the New York State Department of Health for births occurring during 1949, 1950, and 1951 in New York State, exclusive of New York City. The study covered 436,254 single live births over 20 weeks gestation for which data on both birth weight and length of gestation were available. Case fatality rates were determined by birth weight and gestation groups for the entire neonatal period and for 3 age intervals during the neonatal period. For the neonatal period as a whole a characteristic pattern is observed. Within each birth weight group 2500 gm. or less, longer gestation increases the chance of survival; within each gestation group 36 weeks or less, a higher birth weight has a similar effect. A typical example is the range in fatality rates for infants weighing 1001 to 1500 grams at birth. Within this birth weight group, the fatality rate ranges from 40 per cent in the gestation group of 36 weeks or over to 75 per cent in the 24 to 27 weeks gestation group. When fatality rates are computed for 3 successive age periods within the neonatal period, the combined effect of birth weight and gestation produces a characteristic pattern of fatality which is found to be most clearly defined during the first day after birth. However, a similar pattern of fatality is found to exist as well in the age periods from 1 through 6 days and for the remainder of the neonatal period.

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INCIDENCE OF GROSS VISUAL DEFECTS DUE TO RETROLENTAL FIBROPLASIA

PEDIATRICS ◽

10.1542/peds.11.3.238 ◽

1953 ◽

Vol 11 (3) ◽

pp. 238-245

Author(s):

EDWARD R. SCHLESINGER ◽

ISABEL MCCAFFREY

Keyword(s):

New York ◽

Birth Weight ◽

Incidence Rate ◽

New York State ◽

Birth Certificates ◽

Weight Group ◽

Retrolental Fibroplasia ◽

Birth Weight Group ◽

Visual Defects ◽

Period Of Gestation

A study was made of the incidence of gross visual impairment due to retrolental fibroplasia among infants born to residents of New York State, exclusive of New York City, in 1948 and 1949, whose birth certificates indicated birth weights of less than 2000 gm. and who survived to the age of 4 months. Information was obtained regarding 3377 infants or 92.1% of the 3667 in the group described. A total of 50 cases with gross visual defects due to retrolental fibroplasia, or an over-all incidence rate of 1.5%, was found. The incidence rates decreased from 15.9% in the birth weight group under 1000 gm. to 4.3% in 1000-1499 gm. group, and 0.7% in the 1500 to 1999 gm. group. The infants reported to have the shortest period of gestation were found to have the highest incidence, the rate in the group with a period of gestation under seven months being 7.6% as compared with a rate of 0.3% in the group whose gestation period was reported as eight months or more. Although the numbers are small and the measure of gestation as reported on the birth certificate is open to question, the incidence of the condition within each birth weight group was found to be inversely related to the length of gestation. In the 1000-1499 gm. birth weight group, for example, an incidence rate of 7.0% was found among the infants with recorded periods of gestation of less than seven months, as contrasted with a rate of 1.9% among those eight months or more. There was no statistical difference in the incidence of the condition in the group of infants for whom one or more major complications of the mother's pregnancy was reported when compared with the group of infants on whose birth certificates the statement appeared that no such complication occurred. Among infants weighing less than 1500 gm. at birth, a statistically significant variation in the incidence of the condition was found in different regions of the State. The incidence rate, adjusted for differences in weight distribution was found to be 1.7% in males and 1.2% in females. The incidence rate among infants born to mothers under 30 years of age was 1.3%, which is not significantly different from the rate of 1.9% among the infants born to mothers 30 years of age or more.

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