The effect of gestational parity on FEV1 in a group of healthy volunteer women

In the past, studies utilizing within-subject comparisons of small groups o f pregnant women showed that forced expiratory volume in is (FEV1) remained essentially unchanged during pregnancy. However, one of the findings from an epidemiological study was that women with greater number of children exp erienced a faster decline of FEV1. The aim of this study was to examine the effect of parity on FEV1 in a group of healthy volunteer women. To this en d, cross-sectional multiple regression analyses of data from 397 healthy wo men participants in the Baltimore Longitudinal Study of Aging (BLSA) with a mean (range) age of 47.7 (18-92) years were performed. Similar analyses we re done using the younger (50 years or less) and the older (>50 years) subg roups. After controlling for age, height, weight, and smoking, parity as a dichotomous variable was associated with a higher FEV1 in women of child-be aring age (0.1391; P=0.02) but not in the older women. There was a modest l ink with the number of children (P=0.05), with the first child possibly hav ing the greatest effect on FEV1. We could not account for the effect of par ity on FEV1 by the educational level, occupation, health status of the wome n, or by the presence of a cohort effect. Thus the nulliparous state is ass ociated with lower FEV1 in this group of healthy adult women of child-beari ng age.