Volume Hi-l I\ umber I. ParL 2

669 A DECLINE IN VERY LOW BIRTH WEIGHT INFANTS FOLLOWING STATE-WIDE PROJECT TO IMPROVE PREGNANCY OUTCOME S. Kardosx , R. Knuppel, J.T. Harrigan, S. Sun, T. Hegyi, R. Chez and F. Eisner Blue Cross and Blue Shield of New Jersey UMDNJ-Robert Wood Johnson Medical School New Brunswick, New Jersey

Data from 401,000 pregnancies over a four year period (1985-1988) was analyzed. A progressive decline in very low birth weight infants occurred. The rate changed from 40/1000 deliveries in 1985 to 38/1000 in 1987 and 36/1000 in 1988. The rate of low birth weight infants remained at 60/1000 during the entire 4 year period. Several projects to improve pregnancy outcome were instituted during the 4 year period. This data suggests the projects contributed to the reduction in very low birth weight infants.

670 EFFECT Of MAGNESIUM SULfATE THERAPY (M9S04) ON THE BONE MINERAL CONTENT OF WOMEN AND THEIR NEWBORNS

Leon G. Smith. Jr., Richard J. SchanlerX, Pamela BurnsX,

Kenneth J. Moise, Jr., Departments of Obstetrics and

Gynecology and Pediatrics, Chi ldren's Nutrition Research Center, Baylor College of Medicine, Houston, Texas.

Bone mineral abnormal ities have been reported in neonates

whose mothers were treated with Hg504. We investigated the

effects of long- term intravenous HgS04 therapy for tocol ys i s

on the bone mineral content (BHC/BII) of parturients (n=10

MgS04' n=5 control, 24 -32 wk gestation) and their preterm infants_ BHC/BII of the distal 1/3 radius was measured by

single photon absorptiometry in women after delivery, their

infants at 1 wk, and both at 40 wk postconception_ There

were no differences between groups in maternal age (28 = 5

yr, mean ~ SO), parity (median 0, range 0-3), race, body weight, or gestation at delivery (31 = 3 wk). The median

duration and total dose of Hg504 therapy was 23 d (range

8-66 d) and 1298 g (390-4542 g). BHC/BII was simi lar between

study and control groups for mothers, 696 = 62 vs 712 = 17

mg/cm2 , and for preterm infants, 112 = 25 vs 121 = 27

mg/cm2 , respectively. At 40 wk postconception there were no

significant differences in maternal or infant absolute

BHC/BW or in the increment in BHC/BII in the preterm infants_

The relationship between the duration or quantity of HgS04

and maternal or preterm infant BHC/BW at del ivery or 40 wk

was not significant. Prel iminary data suggest that long-term

therapy of parturients with H9S04 does not affect maternal

or pre term infant BHC/BII of the distal radius.

SPO Abstracts 427

671 THE EFFECT OF CIGARETTE SMOKING ON INFANT SIZE AND FETAL GROWTH

Cliver Spx, Goldenberg RL, Cutter GRx, Hoffman HJx, Davis RO, Copper RLx _ The Dept. of OB­GYN, University of Alabama Birmingham & NICHD.

The effect of cigarette smoking on neonatal anthropometric measurements and on fetal growth parameters measured ultrasonically four times during pregnancy was evaluated in 1200 live­born term singletons. In multiple regression analyses adjusting for gestational age at delivery, race, infant sex, maternal age, body mass index, height, and previous low birthweight, a significant (p<.003) dose­response relationship with number of cigarettes smoked was evident in birthweight, crown-heel length, and chest, abdominal, arm and thigh circumferences. Head circumference, arm and femur lengths also showed significant decreases in smokers. All skinfold measurements were less in infants of smokers, but the differences were minimal except in the heaviest smokers_ The effect was most apparent in subscapular skinfold and less 50 in triceps and thigh. When measured by ultrasound, femur length, head circumference, and abdominal circumference were all significantly smaller at 36 weeks showing a clear dose-response (Pi-005 in each case). Although not statistically significant, the femur length was smaller in smokers as early as 16 weeks, head circumference at 30 weeks and abdominal circumference not until 36 weeks. These data suggest that smoking reduces overall fetal growth throughout pregnancy, affecting bone growth as well as fat deposition.

672 WHY DO BLACK AND WHITE NEWBORNS DIFFER IN WEIGHT AT BIRTH?

Gotdenberg RL* Cliver Spl~ Cutter GRX, Hoffman Hi ' Copper R , Neggers Y , Davis RO, Cassady G. Uni v _ of Alabama Birmingham and the NICHD_

The mean birthweight of black infants is consistently less than white infants. In 1500 low income multiparous women, the mean difference was about 200g. Using multiple regression analyses controlling for maternal age, smoking, height, weight, infant sex and a previous low birthweight infant, 41g of the mean black-white difference was due to an excess of preterm births and another 34g due to lower gestational ages in term births. Controlling for factors listed above, and gestational age, a series of regression analyses were used to determine the effect of black race on various newborn measurements. In this model, black race accounted for a decrease in weight of 154 g and 0 _ 53cm in length. There were also significant decreases in head (.44cm), chest (0 . 67cm) and abdominal (0.60cm) circumferences . Arm and leg lengths were not different. Black arm and thigh circumferences were slightly but not signifi­cantly larger. Triceps and thigh skinfolds were not different, but black subscapular skinfolds were smaller (0 . 19mm, p<0_003)_ The ponder a I index in blacks was statistically less_ These data suggest that factors associated with race and not the risk factors studied account for most of the smaller black newborn measurements and for much of the racial difference in birthweight at term.