Reassessing vitamin D supplementation in preterm infants: a prospective study and review of the literature

Risk factors and outcomes of vitamin D deficiency in very preterm infants

BACKGROUND

Vitamin D is essential for bone health and immune system. Vitamin D deficiency (VDD) poses a high-risk to very preterm (VP) infants. This study aimed to evaluate the risk factors associated with VDD in VP infants and its potential clinical outcomes.

METHODS

A retrospective cohort study was conducted on VP infants admitted to the neonatal intensive care unit of a specialized tertiary hospital in Seoul, Republic of Korea, between January 2018 and June 2022. Serum 25-hydroxyvitamin D (25(OH)D) levels and other biochemical parameters were measured between 4 and 6 weeks of age. VDD was defined as a serum 25(OH)D level <20 ng/mL. Prenatal and postnatal risk factors and clinical outcomes were compared between the VDD and non-VDD groups.

RESULTS

Of the 82 VP infants analyzed, 27 (32.9%) were diagnosed with VDD. The VDD group exhibited a significantly longer duration of parenteral nutrition (PN) compared to the non-VDD group (adjusted odds ratio [OR] = 1.12; 95% confidence interval [CI]: 1.008-1.245). Breast milk intake was lower in the VDD group than in the non-VDD group (adjusted OR = 0.976, 95% CI, 0.955-0.999). Notably, calcium levels were significantly lower in the VDD group, while parathyroid hormone levels were significantly higher, compared with the non-VDD group. Additionally, the rickets severity score was higher in the VDD group than in the non-VDD, although the difference was not statistically significant.

CONCLUSIONS

Prolonged PN duration and low breast milk intake significantly increased the risk of VDD in VP infants.

High Initial Dose of Monitored Vitamin D Supplementation in Preterm Infants (HIDVID Trial): Study Protocol for a Randomized Controlled Study

Vitamin D deficiency can escalate prematurity bone disease in preterm infants and negatively influence their immature immunology system. Infants born at 24 + 0/7 weeks to 32 + 6/7 weeks of gestation will be considered for inclusion. Cord or vein blood samples will be obtained within 48 h after birth for 25-hydroxyvitamin D level measurements. Parathyroid hormone and interleukin-6 levels will be measured. Infants will be randomized to the monitored group (i.e., an initial dose of 1000 IU/day and possible modification) or the controlled group (i.e., 250 IU/day or 500 IU/day dose, depending on weight). Supplementation will be monitored up to a postconceptional age of 35 weeks. The primary endpoint is the percentage of infants with deficient or suboptimal 25-hydroxyvitamin D levels at 28 ± 2 days of age. 25-Hydroxyvitamin D levels will be measured at postconceptional age 35 ± 2 weeks. Secondary goals encompass assessing the occurrence of sepsis, osteopenia, hyperparathyroidism, and interleukin-6 concentration. The aim of this study is to evaluate the efficacy of monitored vitamin D supplementation in a group of preterm infants and ascertain if a high initial dosage of monitored vitamin D supplementation can decrease the occurrence of neonatal sepsis and metabolic bone disease.

Vitamin D supplementation improved physical growth and neurologic development of Preterm Infants receiving Nesting Care in the neonatal Intensive Care Unit

OBJECTIVE

To study the effects of vitamin D supplementation on physical growth and neurologic development of very preterm infants receiving nesting intervention in the neonatal intensive care unit (NICU).

METHODS

A total of 196 preterm infants had been hospitalized in NICU with the gestational age (GA) between 28 and 32 weeks. Among them, 98 preterm infants received nesting intervention, and the other 98 cases received both nesting and vitamin D supplementation (400 IU). The interventions were continued until 36 weeks postmenstrual age (PMA). The 25(OH)D serum levels, anthropometric parameters, and Premie-Neuro (PN) scores were compared at 36 weeks PMA.

RESULTS

Higher median serum level of 25(OH)D was found in the nesting + vitamin D [38.40 ng/mL (IQR: 17.20 ~ 70.88) ng/mL] as compared to the nesting group [15.95 ng/mL (IQR: 10.80 ~ 24.30) ng/mL] at 36 weeks PMA. Besides, infants receiving combined nesting intervention and vitamin D supplementation had less proportion of vitamin D deficiency [VDD, 25(OH)D levels < 20 ng/mL] than those receiving nesting intervention alone. After intervention, the anthropometric parameters of infants, including weight, length, BMI and head circumference were improved in the nesting + vitamin D group as compared to the nesting group at 36 weeks PMA, with higher scores of neurological, movement and responsiveness.

CONCLUSIONS

Vitamin D supplementation effectively decreased the prevalence of VDD and led to higher concentrations of 25(OH)D at 36 weeks PMA. This was one more study that supported the necessity of vitamin D supplementation to improve physical growth and neurologic development of preterm-born newborns who received nesting intervention in the NICU.

Breastfeeding and vitamin D

The recent re-emergence of vitamin D deficiency (VDD) and rickets among breastfed infants without adequate sunlight exposure and vitamin D supplementation has been reported worldwide. Breastfed infants are particularly vulnerable to VDD because of the low vitamin D content of breast milk, restricted sunlight exposure, increased pollution, and limited natural dietary sources of vitamin D. The prevalence of VDD in breastfed infants differs vastly between studies and nations at 0.6%-91.1%. The recommended intake of vitamin D for lactating mothers to optimize their overall vitamin D status and, consequently, of their breast milk is 200-2,000 IU/day, indicating a lack of consensus. Some studies have suggested that maternal high-dose vitamin D supplementation (up to 6,400 IU/day) can be used as an alternate strategy to direct infant supplementation. However, concern persists about the safety of maternal high-dose vitamin D supplementation. Direct infant supplementation is the currently available option to support vitamin D status in breastfed infants. The recommended dose for vitamin D supplementation in breastfed infants according to various societies and organizations worldwide is 200-1,200 IU/day. Most international guidelines recommend that exclusively or partially breastfed infants be supplemented with 400 IU/day of vitamin D during their first year of life. However, domestic studies on the status and guidelines for vitamin D in breastfed infants are insufficient. This review summarizes the prevalence of VDD in breastfed infants, vitamin D content of breast milk, and current guidelines for vitamin D supplementation of lactating mothers and infants to prevent VDD in breastfed infants.

Preterm Infants on Early Solid Foods and Vitamin D Status in the First Year of Life—A Secondary Outcome Analysis of a Randomized Controlled Trial

Preterm birth places infants at high risk for mineral and micronutrient deficiencies important for bone health. The aim of this study was to examine whether two timepoints for the introduction of solid foods in preterm infants have an impact on vitamin D status in the first year of life. This is a secondary outcome analysis of a prospective, randomized trial on very low birth weight (VLBW) infants, randomized to an early (10–12th week corrected age) or a late (16–18th week corrected age) complementary-feeding group. Vitamin D status was assessed by blood samples taken at 6 weeks, 6, and 12 months corrected age. In total, 177 infants were randomized (early group: n = 89, late group: n = 88). There was a tendency toward lower levels of serum 25-OH-vitamin D in the early group throughout the first year of life (p = not significant (n.s.)); no differences were detected in the other parameters. At 6 months corrected age, infants of the early group had a significantly higher incidence of vitamin D deficiency. The timepoint of the introduction of solid foods had no impact on the serum 25-OH-vitamin D levels and other parameters important for bone health but showed a tendency toward lower levels in the early-feeding group.

Nutrient composition of preterm mother's milk and factors that influence nutrient content

BACKGROUND

Breast milk feedings are the optimal feeding choice for premature infants. Clinicians depend on accurate nutrient profiles of the breast milk in order to make informed decisions regarding the need for nutrient supplementation. Existing data for nutrient composition of preterm breast milk are dated and not representative of the current population of women delivering prematurely in the United States.

OBJECTIVES

The purpose of this prospective, longitudinal, single-center observational study was to measure the macronutrient and micronutrient composition of breast milk expressed by mothers, including women who self-identify as black, delivering preterm infants at ≤33 completed weeks of gestation.

METHODS

We collected breast milk samples from mothers of preterm infants admitted to the neonatal intensive care unit at Augusta University Medical Center from January 2019 through November 2019. Mother's milk samples were collected on postpartum days 7, 14, 21, and 28 and analyzed for macronutrients (energy, fat, protein, and carbohydrates) and micronutrients (sodium, potassium, chloride, calcium, phosphorus, magnesium, vitamin D, and zinc).

RESULTS

Thirty-eight mothers, mean age 27 ± 5.1 y and majority black (66%), provided milk for the study. The mean estimated gestational age and birth weight were 28.2 ± 2.8 weeks of gestation and 1098 ± 347 g, respectively, with 42% of mothers in the cohort delivering before week 28 of pregnancy. Differences in protein, sodium, potassium, calcium, phosphorus, and zinc concentrations based on race, day, and milk volume were identified. Dilution effects for protein, sodium, chloride, and vitamin D concentrations over time were identified.

CONCLUSIONS

Our study is among the first to characterize breast milk composition from women who delivered extremely preterm infants and adds to the evidence that race, gestational age, and volume influence the composition of preterm mother's milk. These factors should be considered when designing mother's milk-based feeds for premature infants.

Evaluation of vitamin D protocol in the neonatal intensive care unit at Rush University Medical Center

BACKGROUND

In 2017, the neonatal intensive care unit (NICU) at Rush University Medical Center (RUMC) implemented a protocol to provide individualized vitamin D supplementation dosing for very low-birth-weight (VLBW) and very preterm infants. This study evaluated the association of demographic and socioeconomic factors, vitamin D dose, and health indicators, including bone mineral status, measured by alkaline phosphatase and phosphorus levels; linear growth velocity; and occurrence of fractures.

METHOD

This retrospective cross-sectional study included 227 VLBW or very preterm infants (34 VLBW, 12 very preterm, and 181 VLBW and very preterm) born in and discharged from the RUMC NICU between February 1, 2017, and October 31, 2019. Vitamin D dose was classified as adjusted (supplemental dose of 800 IU/day, n = 169) or standard (recommended dose of 400 IU/day, n = 58), per the protocol. Binary logistic and linear regression models were constructed to test the associations between infant and maternal characteristics and vitamin D dose group and between vitamin D dose group and health indicators.

RESULTS

The analysis found a statistically significant association between maternal age, gestational age, infant birth weight, and race/ethnicity and receipt of an adjusted vitamin D dose. No significant associations were found between health indicators and vitamin D dose.

CONCLUSION

Sociodemographic factors may influence vitamin D deficiency in VLBW and very preterm infants in the NICU. At this time, there is insufficient evidence to support a tailored approach, but further research in this area is warranted.