BIRTH WEIGHT OF LIVEBORNS AND RELATED IMPACT FACTORS IN CHINA

Mi J, Lin LM, Liu YL, Zhang XL, Cao LH.

Dept.of Epidemiology, Capital Institute of Pediatrics, Beijing, China.

Objective: To understand national birth weight (BW) status of live-born and to explore the impact factors related to BW in China.

Methods: A national survey on BW of 22350 live-born with stratified sampling method was performed in 1998. Data about local maternal anaemia, Gross National Product (GNP) and altitude were collected as well in all sampling sites.

Results: The ratio of male to female of liveborns was 1.08. Multiple-birth rate and preterm (<37 weeks) rate were 1.8% and 3.5%. Babies born in urban were heavier (3310g) than those in rural (3225g) (t=9.4, P<0.001). Mean BW in coastal, inland and remote area were 3262g, 3254g and 3115g, respectively (F=177.9, P<0.001). Mean BW-by-gestational-age was higher in male than that in female with exception of the 29^th and 31^st gestational week. The increasing trend of fetal weight along with gestational weeks stopped at the 42^nd week. The peaks of weekly increase of fetal weight were found at the 34^th and 37^th gestational week. Multiparity (³4 times) was significantly associated with low BW. BW decreased by 6.1g with each 100m increase in altitude. The incidence of low BW (LBW) (<2500g), intrauterine growth retardation (IUGR) and proportion of IUGR among the LBW varied directly as local maternal anaemia rate, inversely as local GNP.

Conclusions: Mean BW of liveborns in China was similar to developed countries, but varied remarkably with regions. Regional mean BW was associated with local altitude, maternal anaemia rate and socioeconomic status.

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