据国外媒体报道，这张引人注目的照片显示的是一个胎儿在子宫里打哈欠的画面。他显然不用夜以继日的工作，也许是努力成长让他感觉很疲倦。然而英国科学家认为，胎儿在子宫里打哈欠并非感觉疲倦，而是为了满足大脑发育的需要。
研究发现胎儿打哈欠或与大脑发育有关
还在母亲子宫里的小家伙其实已能像常人一样打嗝和吞咽，而新一期美国《公共科学图书馆—综合》刊登的一项研究则显示，胎儿在妊娠中期和晚期还会经常打哈欠。
英国达勒姆大学等机构的研究人员拍摄了7名女胎儿和8名男胎儿24周至36周时的立体超声图像。研究人员发现，24周时，胎儿平均每小时打哈欠6次，随着时间推移，从28周开始打哈欠频率逐渐降低，到36周时完全停止。在图像中，打哈欠与胎儿的其他张嘴行为有明显区分。
研究人员并不清楚胎儿打哈欠的功能，但他们认为这并非胎儿瞌睡的标志。研究负责人、达勒姆大学研究人员纳贾·赖斯兰说，由于打哈欠的行为在胎儿发育过程中遵从可预测的曲线，这种行为可能与胎儿的早期大脑发育有关。
赖斯兰还说，与成人不同，胎儿的哈欠不会传染，打哈欠可能是促进胎儿大脑发育的触发行为，将来有望根据打哈欠频率评估胎儿是否发育正常。
Development of Fetal Yawn Compared with Non-Yawn Mouth Openings from 24-36 Weeks Gestation
Nadja Reissland, Brian Francis, James Mason
Background Although some research suggests that fetuses yawn, others disagree arguing that is it simple mouth opening. Furthermore there is no developmental account of fetal yawning compared with simple mouth opening. The aim of the present study was to establish in a repeated measures design the development of fetal yawning compared with simple mouth opening.Methodology/FindingsVideo recordings were made of the fetal face and upper torso visualized by means of 4D full frontal or facial profile ultrasound recordings. Fifteen healthy fetuses were scanned four times at 24, 28, 32 and 36 weeks gestation. Yawning was distinguished from non-yawning in terms of the length of time it took to reach the apex of the mouth stretch, with yawns being defined as more than 50% of the total time observed. To assess changes in frequency, a Poisson mixed effects model was fitted to the count of number of yawn and simple mouth opening events with age and gender as fixed effects, and person as a random effect. For both yawns and simple mouth openings a smooth varying age effect was significant. The number of yawns observed declined with age from 28 weeks gestation, whereas simple mouth openings were less frequent and the decline was observed from 24 weeks. Gender was not significant either for yawn and simple mouth openings. Conclusions/Significance Yawning can be reliably distinguished from other forms of mouth opening with the potential of using yawning as an index of fetal healthy development.
文献链接：Development of Fetal Yawn Compared with Non-Yawn Mouth Openings from 24-36 Weeks Gestation
