So, where did this recent tummy time debate start in the first place? Prior to the Back to Sleep campaign in 1992, various researchers investigated the benefits and drawbacks of sleeping on the stomach. In one study done in 1983 by Hashimoto, T. et al1, there was evidence to suggest that newborn infants had significantly more quiet sleep on the stomach than on the back with breathing more regular while on the stomach. Further, sleep apnea was less when infants slept on their stomach as well as pulse rate higher. Another study done in 1987 by Masterson J., et al2, looked at the energy expenditure of low birth weight neonates summarizing that “when low birth weight infants are changed from the supine (back) to the prone (stomach) position, energy expenditure decreases, time spent in quiet sleep increases, and time spent awake decreases.” The conclusion was that low birth weight infants’ position of choice was on the stomach.
After the Back to Sleep campaign, there seemed to be a shift in the number of studies that were out to prove that stomach sleeping was harmful. In 2001, Horne, RS., et al33 studied the arousal from sleep in term infants concluding that arousal thresholds were higher when infants slept on the stomach at 2 to 3 weeks and 2 to 3 months, but not at 5 to 6 months. This was considered an “impairment” by the researchers stating this “provides an important insight into its role as a risk factor for sudden infant death syndrome.” Sleeping soundly was considered a benefit by researchers just a few years before, but was now considered an impairment.
In 2009, Ammari A., et al4, took a look at what I would consider the most important factor in this debate-the actual cardiorespiratory and metabolic activity going on in the infant (or the breathing, heart activity and energy expenditure) while asleep. This group studied low birth weight infants who are considered at higher risk for complications than term, healthy weight infants. Sleeping on the stomach “exhibited many physiological differences from sleeping supine (back)”. These included less energy expenditure and less heat loss which influenced cardiorespiratory activity. It was concluded that infants who slept on their stomachs consumed less oxygen and produced less carbon dioxide as well as had a higher respiratory quotient.
What does all this scientific stuff mean? To me, it means that infants tend to sleep more soundly on their stomachs likely due to the positive effects on the cardiorespiratory system. I do not see sleeping soundly as a negative thing for infants. I do see the concern for arousal level by the opposing side IF the baby was in an unsafe sleeping environment. With all the research I have done on this topic, the primary concern is the baby’s reaction to adverse conditions while sleeping like a stuffed animal falling over the face causing him or her to breathe poorly oxygenated air. The argument is if the baby is on his or her back, he or she is not sleeping as soundly and is aroused easier to change position to find a better source of oxygen. Again, the counterpoint stresses the importance of a safe sleeping environment because a baby does not have the muscle strength to do anything about something blocking the face in any position for the first few months.
Ultimately, the decision is undoubtedly yours. Your comfort level will determine how you proceed in this long-standing debate. Have questions or comments? Email me: Stephanie@abouttummytime.com
1. Hashimoto, T, et al, “Postural effects on behavioral states of newborn infants- a sleep polygraphic study” Brain Development 1983; 5(3):286-91
2. Masterson, J, et al, “Prone and supine positioning effects on energy expenditure and behavior of low birth weight neonates.” Pediatrics 1987 Nov; 80(5):689-92
3. Horne, RS, et al, “The prone sleeping position impairs arousability in term infants” J Pediatrics June; 138(6):811-6.
4. Ammari, A, et al, “Effects of body position on thermal, cardiorespiratory and metabolic activity in low birth weight infants” Early Human Development 2009 Aug; 85(8):497-501. Epub 2009 May 5
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