Infant crying and the calming response: Parental versus mechanical soothing using swaddling, sound, and movement

BackgroundFrequent infant crying is associated with parental exhaustion, depression, or even infant hospitalization and shaken baby syndrome. Effective prompt soothing methods are lacking for infants under 6 months. We examined whether swaddling, sound, and movement evoked an immediate calming response (CR) when parents soothed their infants and using a smart crib, and whether infant age affected the CR.MethodsInfants’ CR was assessed in a community sample of 69 infants (0–6 months) in a counterbalanced experiment with two conditions (parent, smart crib) each composed of three two-minute phases (baseline, supine, soothing). During baseline 1, parent and infant were sitting together; in supine 1, fussiness was elicited by putting the infant suddenly supine, followed by parental soothing (shushing and jiggling of the swaddled infant). Baseline 2, supine 2, and soothing by the crib followed. Fussiness was observed and infant heart rate (HR) and heart rate variability (HRV) were recorded. The CR was operationalized as decreased fussiness and HR, and increased HRV during soothing compared to lying supine.ResultsInfant fussiness and HR were lower in both soothing phases compared to the supine phases. Infant HRV tended to be higher during parental soothing than during supine, but did not significantly differ between mechanical soothing and supine. Younger infants responded with a stronger CR (decreased fussiness and increased HRV) to parental soothing, but not to mechanical soothing. For HR, infants’ CR was stronger in the crib than in the parent condition, whereas for HRV, infants’ CR was stronger in the parent condition. For fussiness, infants’ CR tended to be stronger in the parent condition.ConclusionParental and mechanical soothing using swaddling, sound, and movement promptly induced a CR in infants. This has important clinical implications for soothing fussy and crying infants. Future studies should investigate the effects of parental versus mechanical soothing in the home setting.

背景：婴儿频繁啼哭与家长疲惫、抑郁，甚至婴儿住院及摇晃婴儿综合征（shaken baby syndrome）密切相关。目前针对6月龄以下婴儿，仍缺乏高效的即时安抚手段。本研究旨在探究两种场景下，襁褓包裹（swaddling）、声响与晃动能否引发即时安抚反应（calming response, CR）：一是家长亲自安抚婴儿，二是使用智能婴儿床（smart crib）进行安抚；同时探讨婴儿年龄是否会对该安抚反应产生影响。
方法：本研究纳入69名0~6月龄婴儿的社区样本，采用平衡设计实验评估婴儿的即时安抚反应。实验包含两种干预条件（家长安抚、智能婴儿床安抚），每种条件均设置三个持续2分钟的阶段：基线期、仰卧刺激期、安抚期。第一阶段为基线期1：家长与婴儿共同就坐；第二阶段为仰卧刺激期1：将婴儿突然放置于仰卧位以引发烦躁状态，随后由家长对襁褓包裹的婴儿进行嘘声安抚与晃动安抚。后续依次为基线期2、仰卧刺激期2与智能婴儿床安抚期。研究人员对婴儿的烦躁程度进行观察，并记录婴儿的心率（heart rate, HR）与心率变异性（heart rate variability, HRV）。本研究将即时安抚反应操作定义为：相较于仰卧刺激期，安抚阶段中婴儿烦躁程度降低、心率下降且心率变异性升高。
结果：相较于仰卧刺激期，两种安抚阶段中婴儿的烦躁程度与心率均更低。家长安抚阶段的婴儿心率变异性相较于仰卧刺激期有升高趋势，但智能婴儿床安抚阶段与仰卧刺激期的心率变异性无显著差异。年龄更小的婴儿在接受家长安抚时，会表现出更强烈的即时安抚反应（烦躁程度降低、心率变异性升高），但该现象未出现在智能婴儿床安抚场景中。针对心率指标，婴儿在智能婴儿床安抚场景中的安抚反应强度高于家长安抚场景；而针对心率变异性指标，婴儿在家长安抚场景中的反应强度更高。针对烦躁程度指标，婴儿在家长安抚场景中的反应强度有更强的趋势。
结论：通过襁褓包裹、声响与晃动实施的家长亲自安抚与机械安抚，均可迅速引发婴儿的即时安抚反应。该发现对烦躁与啼哭婴儿的临床安抚工作具有重要指导意义。未来可进一步探究居家场景中家长安抚与机械安抚的效果差异。