Low Vitamin D Levels at Birth and Early Respiratory Outcome in Infants With Gestational Age Less Than 29 Weeks

Vitamin D status and the adequacy of its supplementation during the first year of life in preterm infants in northern Japan

BACKGROUND

Vitamin D (VD) deficiency (VDD) is a major concern in preterm infants. The prevalence of VDD in mothers and infants varies between countries and is affected by a range of factors, such as geography and lifestyle. Thus, strategies aimed at preventing VDD must consider the status of each region. However, few reports have explored VDD in preterm infants in Japan and the safety and efficacy of VD supplementation in addressing VDD remain unclear.

METHODS

This study was conducted between September 2019 and October 2022. The participants were 108 preterm infants who were divided into three groups based on their gestational age: <28 weeks (Group 1), 28-33 weeks (Group 2), and 34-36 weeks (Group 3). VD status at birth was assessed, and 25-hydroxyvitamin D (25OHD) levels and biochemical markers were monitored during supplementation with 400 IU/day of VD over the first year of life.

RESULTS

Levels of 25OHD at birth were 10.0 (10.0-16.1), 10.5 (10.0-18.0), and 13.0 (10.0-19.0) nmol/L in Groups 1, 2, and 3, respectively. Infants in all three groups exhibited marked VDD. Their 25OHD levels gradually increased with VD supplementation before plateauing at 6 months. Nevertheless, VDD persisted in the majority of infants at 1 month of age. Serum intact parathyroid hormone levels peaked at 1 month of age and declined thereafter, negatively correlating with 25OHD levels. None of the infants exhibited symptoms of VD toxicity.

CONCLUSION

Preterm infants in northern Japan exhibited substantial VDD, regardless of gestational age. In our cohort, VD supplementation at 400 IU/day safely increased 25OHD levels. However, VD levels improved gradually over the months, and several of these infants developed secondary hyperparathyroidism. Further studies are warranted to determine the optimal VD supplementation dose for preterm infants in this region.

Vitamin D for very preterm infants-determining the how, when, and why

A recent survey study found that 400 IU/day vitamin D is the most common dose in United States neonatal intensive care units. Results of clinical trials are inconsistent, and, therefore, have not determined the optimal vitamin D dose for efficacy and safety in the neonatal intensive care unit. Future studies must consider the unique attributes of perinatal vitamin D metabolism and the potential role of vitamin D in immune function and organ development. IMPACT: Preterm infant vitamin D metabolism is a complex yet important area of research.

Is 25OH Vitamin D Excess before 36 Weeks Corrected Age an Independent Risk Factor for Bronchopulmonary Dysplasia or Death?

Low 25-Hydroxyvitamin D (25(OH)D) in preterm infants is a risk factor for bronchopulmonary dysplasia (BPD), but increased supplementation failed to demonstrate a beneficial effect on BPD. In neonatal animal models, deficiency and excessive vitamin D exposure have been associated with increased mortality and histological alterations in the lung evocative of BPD. Our hypothesis is that 25(OH)D levels ≥ 120 nmol/L are also a risk factor for BPD or death. This retrospective single-center cohort study included only infants born at <31 weeks gestational age without major malformations with at least a determination of 25(OH)D at <36 weeks corrected age and no determination <50 nmol/L. Routine 25(OH)D determination was performed at 1 month and monthly thereafter. A total of 175 infants were included. Infants with BPD or who died had a significantly lower term and weight, but a similar frequency of 25(OH)D ≥120 nmol/L (50.5% vs. 43.9%, p = 0.53). The logistic regression identified weight (OR 0.997, 95% CI [0.995-0.998]) and term (OR 0.737, 95% CI [0.551-0.975]) as significantly associated with BPD or death; the occurrence of excessive 25(OH)D was not significantly associated (OR 1.029, 95% CI [0.503-2.093]). The present study did not demonstrate any significant association between excessive 25(OH)D after one month of age and BPD or death.

Association of Maternal Gestational Vitamin D Supplementation with Respiratory Health of Young Children

This study aimed to evaluate the association between maternal gestational Vitamin D3 supplementation and early respiratory health in offspring. This was a population-based record-linkage study which used data from the French National Health Database System. Maternal Vitamin D3 supplementation consisted of a single high oral dose of cholecalciferol, (100,000 IU) from the seventh month of pregnancy, according to national guidelines. In total, 125,756 term-born singleton children were included, of which 37% had respiratory illness defined as hospital admission due to respiratory causes or inhalation treatment up to 24 months of age. Infants prenatally exposed to maternal Vitamin D3 supplementation (n = 54,596) were more likely to have a longer gestational age (GA) at birth (GA 36-38 weeks, 22% vs. 20%, p < 0.001 in exposed vs. non-exposed infants, respectively). After adjusting for the main risk factors (maternal age, socioeconomic level, mode of delivery, obstetrical and neonatal pathology, birth weight appropriateness, sex, and birth season), the risk of RD was found to be 3% lower than their counterparts (aOR [IC 95%], 0.97 [0.95-0.99], p = 0.01). In conclusion, this study provides evidence for the association between maternal gestational Vitamin D3 supplementation and improved early respiratory outcomes in young children.

Utility of umbilical cord blood 25-hydroxyvitamin D levels for predicting bronchopulmonary dysplasia in preterm infants with very low and extremely low birth weight

BACKGROUND AND OBJECTIVE

There remains controversy regarding vitamin D deficiency and bronchopulmonary dysplasia (BPD) in very low birth weight (VLBW) and extremely low birth weight (ELBW) preterm infants. This study aimed to determine the prevalence of vitamin D deficiency assessed by umbilical cord blood 25-hydroxyvitamin D [25(OH)D] in preterm infants in northeast China and to evaluate the ability and optimal threshold of 25(OH)D for predicting BPD.

METHODS

The clinical data of VLBW and ELBW preterm infants with known cord-blood 25(OH)D levels were analyzed retrospectively. Infants were divided into groups based on their cord-blood 25(OH)D levels and BPD diagnosis. Logistic regression was performed to assess the risk factors for BPD and a nomogram was established. Receiver operating characteristic (ROC) curve analysis was used to evaluate the optimal threshold of cord-blood 25(OH)D concentration for predicting BPD.

RESULTS

A total of 267 preterm infants were included, of which 225 (84.3%) exhibited vitamin D deficiency and 134 (50.2%) were diagnosed with BPD. The incidence of BPD was lower in the group with a 25(OH)D level of >20 ng/ml than in the other groups (P = 0.024). Infants with BPD had lower cord-blood 25(OH)D levels than those without BPD (11.6 vs. 13.6 ng/ml, P = 0.016). The multivariate logistic regression model revealed that 25(OH)D levels (odds ratio [OR] = 0.933, 95% confidence interval [95% CI]: 0.891-0.977), gestational age (OR = 0.561, 95% CI: 0.425-0.740), respiratory distress syndrome (OR = 2.989, 95% CI: 1.455-6.142), and pneumonia (OR = 2.546, 95% CI: 1.398-4.639) were independent risk factors for BPD. A predictive nomogram containing these four risk factors was established, which had a C-index of 0.814. ROC curve analysis revealed that the optimal cutoff value of 25(OH)D for predicting BPD was 15.7 ng/ml (area under the curve = 0.585, 95% CI: 0.523-0.645, P = 0.016), with a sensitivity of 75.4% and a specificity of 42.9%.

CONCLUSIONS

A cord-blood 25(OH)D level of <15.7 ng/ml was predictively valuable for the development of BPD. The nomogram established in this study can help pediatricians predict the risk of BPD more effectively and easily.