Changes in Birth Weight between 2002 and 2012 in Guangzhou, China

<div><p>Background</p><p>Recent surveillance data suggest that mean birth weight has begun to decline in several developed countries. The aim of this study is to examine the changes in birth weight among singleton live births from 2002 to 2012 in Guangzhou, one of the most rapidly developed cities in China.</p><p>Methods</p><p>We used data from the Guangzhou Perinatal Health Care and Delivery Surveillance System for 34108 and 54575 singleton live births with 28–41 weeks of gestation, who were born to local mothers, in 2002 and 2012, respectively. The trends in birth weight, small (SGA) and large (LGA) for gestational age and gestational length were explored in the overall population and gestational age subgroups.</p><p>Results</p><p>The mean birth weight decreased from 3162 g in 2002 to 3137 g in 2012 (crude mean difference, −25 g; 95% CI, −30 to −19). The adjusted change in mean birth weight appeared to be slight (−6 g from 2002 to 2012) after controlling for maternal age, gestational age, educational level, parity, newborn's gender and delivery mode. The percentages of SGA and LGA in 2012 were 0.6% and 1.5% lower than those in 2002, respectively. The mean gestational age dropped from 39.2 weeks in 2002 to 38.9 weeks in 2012. In the stratified analysis, we observed the changes in birth weight differed among gestational age groups. The mean birth weight decreased among very preterm births (28–31 weeks), while remained relatively stable among other gestational age subcategories.</p><p>Conclusions</p><p>Among local population in Guangzhou from 2002 to 2012, birth weight appeared to slightly decrease. The percentage of SGA and LGA also simultaneously dropped, indicating that newborns might gain a healthier weight for gestational age.</p></div

Percentage distribution of singleton live births by birthweight, born in 2002 and 2012.

<p>(A, 28–41 completed weeks of gestation; B, 28–31 completed weeks of gestation; C, 32–36 completed weeks of gestation; D, 37–38 completed weeks of gestation; E, 39–40 completed weeks of gestation; F, 41 completed weeks of gestation).</p

Maternal and newborn characteristics among singleton live births in 2002 and 2012.

<p>Data are expressed as mean ± standard deviation or n(%).</p><p>Maternal and newborn characteristics among singleton live births in 2002 and 2012.</p

Percentage of singleton live births with SGA, AGA and LGA, by maternal and newborn characteristics in 2002 and 2012.

<p>SGA, small for gestational age; AGA, appropriate size for gestational age; LGA, large for gestational age.</p><p>^* Standardized to the 2002.</p><p>Percentage of singleton live births with SGA, AGA and LGA, by maternal and newborn characteristics in 2002 and 2012.</p

Changes in birth weight among singleton live births between 2002 and 2012.

<p>Data are expressed as mean ± standard deviation.</p><p>^* Adjusted for maternal age, gestational age, educational level, parity, newborn's gender and delivery mode.</p><p>^** Adjusted for maternal age, educational level, parity, newborn's gender and delivery mode.</p><p>Changes in birth weight among singleton live births between 2002 and 2012.</p