Facial expressions such as laughter and crying develop before birth and become more complex as the pregnancy progresses to 36 weeks of gestation, according to a study led by British researcher Nadja Reissland.
The development of facial movements in a fetus is essential for various functions after birth - the infant sucking movement required for feeding, jaw and tongue movements necessary for speech, and movements in the face necessary for facial expressions. It is also necessary for the postnatal bonding between the baby and parents and theoretically for the study of the origins of affect.
AdvertisementAlthough facial muscles begin to develop by 8 weeks and all the muscles used in facial expressions are formed by 16 weeks, it is possible to evaluate fetal facial expressions only between 24-36 weeks as the adipose tissue builds up during this period.
The Facial Action Coding System (FACS) was available for infants and for adults but no comprehensive coding system applied to fetuses. So, the aim of this study was to develop a coding system for fetal facial movement to address two questions - 1) Does the complexity of facial movement increase with fetal age? And 2) Do facial movements associated with positive and negative emotions emerge from the second to third trimester of pregnancy?.
The researchers studied the fetal facial expressions by applying the Facial Action Coding System (FACS) on modern 4-D ultrasound recordings. With increasing gestational age fetal movements of the face, limbs and torso become correlated with the structural development of the central nervous system (CNS). This development demonstrates that the connection between cerebral cortex and peripheral structures of the fetus are functional. In compromised fetuses this development is at variance from normal fetuses. Therefore by evaluating fetal expressions it is possible to predict the healthy brain function of the fetus.
Based on research using facial muscle movements to code recognizable facial expressions in adults and adapted for infants, the scientists have defined two distinct fetal facial movements- 'cry-face-gestalt' and 'laughter-gestalt'. Both the movements are made up of up to 7 distinct facial movements. During the study when two healthy female fetuses were scanned at different gestational ages in the second and third trimester it was observed that the number and complexity of simultaneous movements increased with gestational age. It was noted that between 24-35 weeks the mean number of co-occurrences of 3 or more facial movements increased from 7-69 percent. The number of co-occurrences of 3 or more movements making up a 'cry-face gestalt' facial movement increased from 0-42 percent while that of 'laughter-face gestalt' increased from 0-35 percent. Recognizable facial expressions were also observed to develop during this period.
Dr Nadja Reissland from Durham University, the lead researcher of this study says, 'This research provides the first evidence of developmental progression from individual unrelated facial movements toward fetal facial gestalts. We propose that there is considerable potential of this method for assessing fetal development: Subsequent discrimination of normal and abnormal fetal facial development might identify health problems in utero'. This means, this coding and analysis allows researchers to 'objectively trace the increasing complexity of movements over time which results in recognisable facial expressions'.
Thus this fetal facial movements coding method:
• can serve as a marker for normal development;
• has considerable potential for assessing the integrity of the fetal central nervous system;
• can possibly be used for the detection of functional or structural brain disorders;
• can subsequently discriminate between normal and abnormal fetal facial development to identify health problems in utero.
Reference: Do Facial Expressions Develop before Birth?; Nadja Reissland et al; Plos One 2011.