Maternal age and parity effects on human birth weight: a hospital survey from Lahore (Punjab), Pakistan.

The study is based on a total sample of 994 live births (470?$ and 524 dV) and 15 stillbirths in a hospital survey from Lahore (Punjab), Pakistan. The mean birth weight of newborns is 109±0109.025+0.95. The mean birth weight for female infants is 1G7.31±1.19 and that of male births 110.74+.0.71. The difference between the two sexes is highly significant (t 992 =2.46; P <0.02). Lighter males are born to younger mothers (<19 years) than the females (t 48 =0.47; P>0.6) but heavier male births are observed in the first birth order than the female babies (t 335 =0.93; P>0.3). The stillborn arc lighter than the live births with an average difference of 4.87 oz. The liveborn males and females are heavier than the male and female stillbirths with an average difference of 4.92 oz and 6.51 oz respectively. The advancing maternal age shows highly significant negative effects on male birth weights (P<0.01), and non-significant positive effects on female (P>0.1). Birth order has highly significant positive influence on male birth weights (P<0.001), but insignificant effects on female birth weights. Maternal age indicates non-significant effects on sex ratio (P>0.1); however birth order shows highlv significant negative effects on sex ratio(P <0.01) (JPMA30:131, 1980).