The Effect of Order of Birth and Age of Parents Upon Neonatal Mortality

Abstract

T | THIS STUDY deals with neonatal mortality as it is affected by order of birth and age of parents. It is felt that variations in neonatal mortality is dependent upon congenital differences to a larger degree than are variations in adult or infant mortality. In New York state, exclusive of New York City, infant mortality was 51.3 per 1000 live births in i9i5 and I7.2 in I936, a reduction of 66 percent. The corresponding rates for neonatal mortality (deaths of infants under one month) were 49.3 and 3 I.6, a reduction of only 36 percent. If further significant reductions are to occur, they will have to be in neonatal mortality. We studied 82,140 live births which occurred in New York state, exclusive of New York City, in I936. (See cited paper for method.) Of these, 2566 infants died under one month of age. The neonatal mortality for this group was, therefore, 31.2 per 1000 live births. I. Order of Birth. First births formed 28.8 percent of all births in i9i7 and 36.o percent in I936, an increase of 25 percent. Similarly, the proportion of second births was 9.5 percent higher in I936 than in i9i7. The births of order three and higher were proportionately fewer in I936. The largest reduction occurred among births of order six to nine. It is of interest to note that births of order ten and over were relatively as frequent in I936 as they were in i9i7. First and second births formed 6o percent of all births in 1936 and only 25 percent of all the births were of order higher than three. The neonatal mortality was high for first births, dropped to a minimum for second births, increased slightly for third and fourth births and rose sharply beginning with fifth births. The rate for first births was 24 percent higher than for the minimum, while the rates for births of order ten and over was more than twice as high as that for second births. The neonatal mortality for boys was 30 percent higher than that for girls for all orders of birth. First births formed 39 percent of all births in urban and only 33 percent in rural areas. The neonatal mortality was slightly lower in the cities for practically all birth orders. Births out of Wedlock and Plural Births. The rates by order of birth are