季节对上海地区婴幼儿体格生长的影响

Seasonality of Growth in Shanghai Infants.

【目的】 研究婴幼儿生长的季节性变化及出生季节对生长的近期和远期影响。 【方法】 对上海市枫林街道 0～ 2岁婴幼儿纵向健康监测资料进行分析。 【结果】 上海地区婴幼儿的生长有着明显的季节性。身高速率在春夏季长得快 ,体重和身体重指数 (BMI)在秋冬季增加较多。出生季节对出生后生长有影响作用。夏季出生的小儿在 0～ 2岁各年龄段的身高均比其他季节出生的同龄儿高。小儿 1月龄的身高、1～ 2 4个月身高增值和 2 4月龄身高均与出生月份呈显著的曲线相关 (P <0 .0 5 )。 6月份出生的小儿在 1月龄时身高比 1月份出生的同龄儿高约 2 .0cm ,二者差距随年龄的增加逐渐减少 ,到 2周岁时差值减至约 0 .7cm。 【结论】 婴幼儿的生长呈明显季节性变化 ,出生季节对出生后生长有较长远的影响。在生长的监测和研究中 ,季节应作为一个影响因素给予考虑。

To describe the seasonal growth patterns in Shanghai infants and to investigate the long based effect of birth season on postnatal early human growth. This community based longitudinal study was carried out in Fenglin community,Shanghai,China.The study series consisted of 4 128 full term children,born between 1st January 1980 and 31 st December 1990.Children was followed up monthly from 1 to 6 months,three monthly from 6 to 12 months,six monthly from 12 to 24 months.The year was divided into four seasons:spring,summer,autumn and winter.Weight gain,length gain and changes in body mass index(BMI) were calculated over the seasons of the year. The data demonstrated a clear and consistent seasonality in growth velocity for length,weight and body mass index(BMI) over all birth year cohorts.The infants tended to grow faster in height in spring and summer and faster in weight and BMI in autumn and winter in all age intervals.There was some long term seasonal effect on early human growth;infants born in the summer attained higher body length than those born in other seasons at each age,whereas the differences of mean SDS values for weight and BMI in the four seasons were less marked.The mean length SDS value at 1 month of age,delta SDS value between 1 to 24 months of age,and the mean length SDS value at 12 months of age were all significantly( P <0.05) associated with birth months.Their cubic regression functions were:Length SDS 1month = 0.881 241+0.433 532*Birthmonth 0.048 418*Birthmonth 2+0.001 364*Birthmonth 3;Delta length SDS 1,24months =0.109 794 0.285 579*Birthmonth+0.035 611*Birthmonth 2 0.001 196*Birthmonth 3;Length SDS 24months = 0.720 517+0.134 98*Birthmonth-0.012 696*Birthmonth 2+0.000 236*Birthmonth 3.According to these functions,the mean length SDS value at 1 month of age was higher in infants born in June than those born in January,the mean difference about 0.8 standard deviation score,or 2.0 cm.At 24 months of age this difference was reduced to about 0.3 standard deviation score,or 0.7 cm. [Conclusions] There is a clear seasonality in growth in Shanghai infants.Birth month has some association with attained size,but this is reduced during the first two years of life.Seasonality in infant growth represents a significant potential confounding factor in growth studies,such as nutritional clinical trials.