Patterned auditory stimulation and suck dynamics in full-term infants

The association between infant non-nutritive suck and oral motor development

This study investigated if non-nutritive suck (NNS) at 3 months is related to subsequent oral motor and motor skills using caregiver-reported scores on the Child Oral and Motor Proficiency Scale (ChOMPS) at 12 months in a cohort of 69 full-term infants and their caregivers. Longer NNS burst durations were associated with lower oral motor coordination and total ChOMPS scores. More NNS cycles per minute was associated with lower complex motor movement scores. More NNS bursts, cycles per burst, and cycles per minute were related with lower total ChOMPS scores. Early NNS outcomes can provide valuable insight in future neuromotor development.

Associations between biomarkers of prenatal metals exposure and non-nutritive suck among infants from the PROTECT birth cohort in Puerto Rico

Background/Aim

Infant non-nutritive suck (NNS) has been used as an early marker of neonatal brain function. Although there is an established relationship between prenatal exposure to certain metals and brain development, the association between metal exposure and NNS has not been explored. Therefore, in this study we assessed associations between maternal urinary metal(loid) concentrations and NNS measurements among infants from the Puerto Rico PROTECT birth cohort. We hypothesized that maternal urinary metal(loid) concentrations are significantly associated with infant NNS measures in a sex-dependent manner.

Methods

We measured urinary concentrations of 14 metal(loid)s in pregnant women at up to three time points in pregnancy. The geometric mean of each metal(loid) for each pregnant woman was calculated and used as an exposure measurement across gestation. NNS measurements (duration, frequency, amplitude, bursts/min, cycles/burst, cycles/min) were collected from infants between 4 and 6 (±2 weeks) weeks of age using our custom research pacifier. Linear regression was used to estimate associations between urinary metal(loid) concentrations across pregnancy and continuous NNS variables. Sex-specific effects were estimated using interaction terms between NNS variables and infant sex.

Results

We observed significant positive associations between mercury, manganese, and tin with NNS duration (mercury: %Δ = 1.08, 95% CI: 0.42, 1.74; manganese: %Δ = 0.67, 95% CI: 0.15, 1.20; tin: %Δ = 0.83, 95% CI: 0.17, 1.49) and NNS cycles/burst (mercury: %Δ = 1.85, 95% CI: 0.58, 3.11; manganese: (%Δ = 1.37, 95% CI: 0.40, 2.34; tin: %Δ = 1.68, 95% CI: 0.46, 2.91). Furthermore, the association between NNS cycles/min with cadmium (%Δ = 8.06, 95% CI: 3.33, 12.78), manganese (%Δ = 4.44, 95% CI: 1.40, 7.47), and tin (%Δ = 4.50, 95% CI: 0.81, 8.18) were in the opposite direction from its association with zinc (%Δ = -9.30, 95% CI: -14.71, -3.89), as well as with copper (%Δ = -6.58, 95% CI: -12.06, -1.10). For the sex-stratified analysis, the negative associations between metal(loid)s and NNS duration were predominantly driven by male infants; however, the negative associations between metal(loid)s and NNS bursts/min were mainly driven by female infants.

Conclusion

We observed significant associations between prenatal metal(loid) exposure and NNS measurements among infants from the ongoing Puerto Rico PROTECT cohort. Similar to previous studies that have demonstrated associations between NNS and subsequent neurodevelopment, this study highlights the potential of NNS as a quantitative index to measure altered neurodevelopment from prenatal metal(loid) exposures. We believe this study will inform future efforts aimed at reducing health risks related to early life metal exposures, such as developing early identification of metal-induced adverse outcomes in child neurodevelopment.

Non-nutritive suck and airborne metal exposures among Puerto Rican infants

Air pollution has been shown to impact multiple measures of neurodevelopment in young children. Its effects on particularly vulnerable populations, such as ethnic minorities, however, is less studied. To address this gap in the literature, we assess the associations between infant non-nutritive suck (NNS), an early indicator of central nervous system integrity, and air pollution exposures in Puerto Rico. Among infants aged 0-3 months enrolled in the Center for Research on Early Childhood Exposure and Development (CRECE) cohort from 2017 to 2019, we examined associations between exposure to fine particulate matter (PM_2.5) and its components on infant NNS in Puerto Rico. NNS was assessed using a pacifier attached to a pressure transducer, allowing for real-time visualization of NNS amplitude, frequency, duration, cycles/burst, cycles/min and bursts/min. These data were linked to 9-month average prenatal concentrations of PM_2.5 and components, measured at three community monitoring sites. We used linear regression to examine the PM_2.5-NNS association in single pollutant models, controlling for infant sex, maternal age, gestational age, and season of birth in base and additionally for household smoke exposure, age at testing, and NNS duration in full models. Among 198 infants, the average NNS amplitude and burst duration was 17.1 cmH₂O and 6.1 s, respectively. Decreased NNS amplitude was consistently and significantly associated with 9-month average exposure to sulfur (-1.026 ± 0.507), zinc (-1.091 ± 0.503), copper (-1.096 ± 0.535) vanadium (-1.157 ± 0.537), and nickel (-1.530 ± 0.501). Decrements in NNS frequency were associated with sulfur exposure (0.036 ± 0.018), but not other examined PM components. Our findings provide new evidence that prenatal maternal exposure to specific PM components are associated with impaired neurodevelopment in Puerto Rican infants soon after birth.

Associations of gestational phthalate exposure and non-nutritive suck among infants from the Puerto Rico Testsite for Exploring Contamination Threats (PROTECT) birth cohort study

BACKGROUND

Infant non-nutritive suck (NNS), or sucking on a pacifier with no nutrients being delivered, has been used as in index of brain function and has been linked to subsequent neurodevelopment. Yet, no data are available connecting NNS to environmental exposures in utero. The goal of this study was to examine the relationship between gestational exposure to phthalates (a group of chemicals found in personal care products, PVC plastics, and other products) and NNS among infants in a birth cohort study in Puerto Rico.

METHODS

Urinary phthalate metabolite levels were measured in women at up to three time points in pregnancy as a measure of in utero exposure to the child. We calculated the geometric mean of each metabolite for each woman as a measure of exposure across gestation. Infants had their NNS sampled using our custom research pacifier between 4-6 (± 2 weeks) weeks of age, yielding the following NNS dependent measures: cycles/burst, frequency, amplitude, bursts/min, and cycles/min.

RESULTS

Two hundred and eight mother-infant dyads completed this study We used multiple linear regression to assess associations between individual phthalate metabolites and NNS measurements, adjusting for infant sex, birthweight, and urinary specific gravity. An interquartile range (IQR) increase in mono carboxyisononyl phthalate across pregnancy was associated with 3.5% (95%CI: -6.2, -0.8%) lower NNS frequency and 8.9% (0.6, 17.3%) higher NNS amplitude. Similarly, an IQR increase in mono-2-ethylhexyl phthalate was also associated with 3.4% (-6.5, -0.2%) lower NNS frequency, while an IQR increase in di-2-ethylhexyl terephthalate metabolites was associated with 11.2% (2.9, 19.5%) higher NNS amplitude. Gestational exposure to phthalates may alter NNS amplitude and frequency in full-term infants. These findings indicate that the infants may be increasing their NNS amplitude to compensate for their slower NNS frequency. These preliminary findings could have important clinical implications for earlier detection of exposure-related deficits in neurofunction as well as implications for subsequent neurodevelopment and related interventions.

Changes in non-nutritive suck between 3 and 12 months

BACKGROUND

Non-nutritive suck (NNS) is one piece of the complex oral feeding process, yet there is paucity on how it develops throughout the first year of life.

AIMS

To determine changes in infant NNS between 3 and 12 months of age.

STUDY DESIGN

Twenty-six full-term infants (65% male) completed this study. All infants were offered our custom research pacifier to attain a quantitative analysis of their suck pattern. Based on quantitative analyses of NNS cycle count, the best 2 min of infants' suck were selected and analyzed.

OUTCOME MEASURES

NNS duration, amplitude, cycles/burst, frequency, cycles, and bursts.

RESULTS

NNS duration, bursts, cycles/burst and cycles significantly decreased from 3 to 12 months, yet amplitude significantly increased over the same time period. Additionally, no significant differences were evident for NNS frequency. Three-month-old infants produced a median of 4.50 suck bursts per minute that contained 9.60 cycles/burst, resulting in a burst duration of 4.74 s. The median NNS frequency was 2.09 Hz, with an average amplitude of 14.05 cmH₂0. Twelve-month-old infants produced a median of 2.50 suck bursts that contained 3.75 cycles/burst, resulting in a burst duration of 1.67 s. The median NNS frequency was 2.11 Hz with an amplitude of 19.75 cmH₂0.

CONCLUSION

Full-term infants significantly change their NNS duration, amplitude, burst number, cycles/burst and cycle number with no significant changes present in NNS frequency between 3 and 12 months. Knowledge of NNS emergence and maturation during the first year of life is imperative for proper NNS assessment so that healthcare professionals can identify delays.

Social visual stimuli increase infants suck response: A preliminary study

This study investigated whether visual stimuli (FACES vs. CARS) combined with the presence of maternal scent can influence suck patterning in healthy infants. Fifteen healthy full-term infants (six months and younger) were exposed to their mother’s scent during a visual preference paradigm consisting of FACES vs. CARS stimuli while sucking on a custom research pacifier. Infants looked significantly longer to the FACES compared to CARS, p = .041. Repeated Measures ANOVA revealed a significant main effect for non-nutritive suck (NNS) bursts and visual stimuli (p = .001) with the largest differences evident between FACES and when the infant looked away from the visual stimuli (p = 0.008) as well as between FACES and CARS (p = 0.026). These preliminary findings suggest that infants have more suck attempts when looking at FACES in the presence of maternal scent thereby indicating potent links between visual preference and suck behavior.

Not All Pacifiers Are Created Equal: A Mechanical Examination of Pacifiers and Their Influence on Suck Patterning

PURPOSE

Many pacifier companies advertise that their product is the "best choice" to support proper sucking, feeding, and dental development; however, very little evidence exists to support these claims. As the primary differences across pacifiers are structural and mechanical, the goals of this study were to measure such properties of commercially available pacifiers and to examine how these properties alter suck patterning in healthy, full-term infants.

METHOD

Seven commonly utilized pacifiers were mechanically tested for pull and compression stiffness levels and categorized into nipple shape types based on their aspect ratio. Next, 3 pacifiers (Soothie, GumDrop, and Freeflow) with the most salient differences in pull stiffness levels with 2 different pacifier nipple types were tested clinically on 16 full-term infants (≤ 6 months old) while measuring non-nutritive suck (NNS).

RESULTS

A repeated measures analysis of variance revealed significant differences between NNS burst duration (p = .002), NNS cycles per burst (p = .002), and NNS cycles per minute (p = .006) and pacifier type. With each significant dependent measure, pairwise comparisons showed that the GumDrop and Freeflow pacifiers differed significantly on these measures.

CONCLUSIONS

Pacifier compression, pull stiffness, and nipple shape type yield different NNS dynamics. These findings motivate further investigation into pacifier properties and suck patterning in young infants.