How Newborns Develop Hearing and Vision

A newborn's hearing and vision are assessed, and he or she will respond to the voice of his or her mother and father, but will not respond to unfamiliar voices. Hearing and vision are similar to adult-level abilities, and newborns can focus on objects that are about nine inches, or about 23 cm, away. Newborns have a fully intact blink reflex, and may have edema around the eye, depending on how the newborn was born. This swelling will resorb within a few days.

In a study of 90 singleton live newborns, the authors investigated the fetal age and anthropometric parameters of the infants. The authors conducted statistical analyses using SPSS windows version 20.0. The authors found that fetal age is a good predictor of the anthropometric characteristics of neonates. However, the researchers noted that there was no consensus on the exact gestational age of newborns. This makes the study difficult to interpret.

The assessment of a Neonate should begin with a thorough history and careful observation. Historical considerations include familial predispositions to disease, the course of pregnancy, and labor and delivery. After establishing a baseline for physical examination, the newborn should be observed for changes in body temperature and muscular tone. The infant's heart rate should be in the range of 160 to 180 beats per minute. The respiratory and femoral pulses should be checked gently and bilaterally.

Evoked otoacoustic emissions (EOE) have been studied in newborns, and the effects of hyperbilirubinemia on the auditory pathway in neonates were evaluated in a study. The ARC is a microprocessor controlled, fully automated machine that was designed for use in hearing screening of neonates at full term. Over a three-year period, this device was evaluated in 6000 neonates. It detected hearing impairment in 20 percent of infants who failed at least two tests. The remaining twenty-one babies were found to be normal or with a mild to moderate hearing impairment.

Audiometry in neonates is still the gold standard for diagnosing hearing loss. However, most referral centers do not offer audiometric screening for infants younger than 6 months old. Behavioral audiometry, which requires no special equipment, is an alternative. ABRs can detect auditory neural disorders in neonates and confirm the thresholds identified by behavioral audiometry. These tests are very time-consuming and expensive and should be performed only when absolutely necessary.

There is still much to be learned about how the human brain develops vision. Behavioral studies of monkeys and humans have revealed that basic binocular connections are immature at birth. Neonatal humans cannot detect objects embedded in random dot stereograms. Monkeys, on the other hand, develop stereopsis quickly after they reach four weeks of age. The lack of stereopsis in newborns may be related to the absence of disparity-sensitive neurons in the V1 of the brain.

However, the metabolic needs of the developing retina may never be fully known. Thus, deprivation of nutrients through RD or low OPP may worsen the visual outcomes in neonates. Although ROP is more common among premature infants, some studies have shown that the condition can affect infants of any race. This suggests that severe ROP may lead to even worse vision problems in the long run. In the short term, it is not clear whether or not the deficiency of nutrients in the neonatal retina will result in the development of ROP.

Using a novel ultrasound technique, we have compared gastric emptying in preterm infants to preterm infants and calculated the half-emptying time for neonates. Our neonates received a nasogastric feed of breast milk or formula milk and a second alternative feed at the next feeding. Our neonates had their antral cross-sectional areas measured before and after feeding and their half-emptying time was determined as the difference in ACSA of 50%.

The results of this study are based on a large number of neonates, and include a large percentage of preterm newborns. The weighting method we used gave more weight to individuals' data points and to the scintigraphic measurements as the gold standard. This suggests that the type of gastric emptying data we used in this study is more reliable than a measure of gastric emptying half-life, which is prone to bias from calculation and extrapolation.

The immune response of the neonate is characterized by a shift towards Th2 cell responses. This shift is mediated by altered expression of IL-27 and IL-12 genes in cord blood derived macrophages. Neonatal lung immune responses show a shift toward Th2 T-cell responses. Neonates also lack CD103+ DCs in the lungs, affecting their susceptibility to cryptosporidium parvum infection. Moreover, neonatal lungs contain lower numbers of plasmacytoid DCs, and less conventional DCs.

A newborn has a developing immune system, and the microbial environment they are exposed to is highly contaminated. Infections cause 40% of the three million neonatal deaths worldwide. Maternally transferred maternal antibodies play an important role in early neonatal defense against pathogenic organisms. Passive protection, however, is rapidly lost by six months of age. For example, immunity to measles and varicella is largely reduced until at least the age of eight.

The lungs of the newborn are full and able to produce only a small fraction of the total lung volume (FRC). This is due to a lack of surfactant, which takes days to synthesize. Neonatal lungs have a very high FRC and large pressure swings are required during the first few breaths. The tidal volume of neonates is very small and their autoPEEP can only be as high as 35 cm H 2 O.

Infancy brings with it many modifications. The rib cage is more horizontal in newborns, which results in reduced lung compliance. In addition, neonates have higher minute ventilation-to-FRC ratios than adult lungs. Neonatal lungs are characterized by a flattened diaphragm and small airways, which can close during inspiration. Despite these changes, neonates are capable of increasing the FRC through various manoeuvres.