An infant’s first cry may occur not in the delivery room, but in the womb, study suggests.
With the help of video-recorded ultrasound images, the investigators found that a group of third-trimester fetuses showed evidence of “crying behavior” in response to a low-decibel noise played on the mother’s abdomen.
Fetuses showed a “startle” response to the noise, along with deep inhalations and exhalations, an open mouth and a “quivering” chin - all signs of crying.
The behavior, seen in 11 fetuses, began as early as the 28th week of pregnancy.
It was only by chance that the researchers made their observations, said study co-author Dr. Ed Mitchell of the University in Auckland in New Zealand.
The ultrasounds and noise stimulation were performed as part of research looking into the effects of maternal smoking and cocaine use during pregnancy. At first, the researchers thought the fetal responses they saw might be seizures, but when they took a closer look at the video recordings, they realized the fetuses’ behavior was analogous to an infant’s crying.
It’s not surprising that fetuses this age would show such behavior, Mitchell said, since premature infants born even earlier than the 28th week of pregnancy can cry.
“But it had never been observed or recognized for what it is,” he said of the fetal crying.
The researchers first noted the crying behavior in an ultrasound of a 33-week-old fetus. When the stimulus - noise and vibration akin to a rumbling stomach - was placed on the mother’s abdomen, the fetus “startled” and turned its head. That was followed by heavy breaths, jaw opening and chin quivering, according to the researchers.
Subsequent ultrasounds found similar behavior in 10 fetuses, all 28 weeks old and up, that lasted for 15 to 20 seconds after the noise exposure.
“This phenomenon, suggests a prenatal origin of crying”, Mitchell report.
The findings have developmental implications, according to Mitchell and his colleagues. To “cry,” they note, the fetus would need not only the movement capability, but also the necessary sensory and brain development to process the offending sound and recognize it as something negative.
In a recent, controversial study, researchers at the University of California, San Francisco concluded that fetuses are unlikely to feel pain before the 29th week of pregnancy. It’s believed, Mitchell noted, that the “pain pathways” in the brain begin to develop between weeks 23 and 30.
SOURCE: Archives of Disease in Childhood Fetal Neonatal Edition, September 2005.
Revision date: June 14, 2011
Last revised: by Jorge P. Ribeiro, MD