Prentice A M, Whitehead R G, Watkinson M, Lamb W H, Cole T J
Lancet. 1983 Mar 5;1(8323):489-92. doi: 10.1016/s0140-6736(83)92188-8.
Gambian women, who show marked seasonal fluctuations in energy balance, were offered a dietary supplement during pregnancy. This resulted in a net energy increment of 431 kcal/day. In the wet season, when the women were normally in marked negative energy balance due to food shortages and a high agricultural work load, the supplementation improved birth-weight by a mean of 224 g and reduced the incidence of low-birth-weight babies (less than 2.5 kg) from 28.2% to 4.7%. In the dry season, when the women were previously in positive energy balance despite an energy intake of only 60% of the recommended dietary allowance, the supplement had no beneficial effect on birth outcome. This threshold effect indicates the need to identify truly at-risk groups for prenatal supplementation programmes in developing countries.
能量平衡呈现明显季节性波动的冈比亚女性在孕期获得了膳食补充剂。这使得每日净能量增加了431千卡。在雨季，由于食物短缺和繁重的农业劳动，这些女性通常处于明显的能量负平衡状态，补充剂使出生体重平均增加了224克，并将低出生体重婴儿（低于2.5千克）的发生率从28.2%降至4.7%。在旱季，尽管这些女性的能量摄入量仅为推荐膳食摄入量的60%，但她们之前处于能量正平衡状态，补充剂对出生结局没有有益影响。这种阈值效应表明，在发展中国家，有必要确定真正处于风险中的群体以实施产前补充计划。
