Early life growth trajectories in cystic fibrosis are associated with lung function at age six

BACKGROUND

Higher growth percentiles are associated with more favorable lung function in cystic fibrosis (CF), prompting the creation of CF Foundation (CFF) nutritional guidelines.

OBJECTIVES

To describe early childhood growth trajectories within CF, to determine if growth trajectories are associated with differences in lung function at age six, and to identify factors that differ between trajectory groups.

METHODS

Retrospective cohort study of children diagnosed with CF and born 2000-2011 using the US CFF Patient Registry. Annualized growth parameters prior to age six were included in group-based trajectory modeling to identify unique early life growth trajectories. FEV1 percent predicted (FEV1pp) at age six was compared between trajectory groups using linear regression. Factors associated with group membership were identified using multinomial logistic regression.

RESULTS

6,809 children met inclusion criteria. Six discrete growth trajectories were identified, including three groups that began with growth parameters >50th percentile, termed: "always high", "gradual decliner", "rapid decliner", and three which began with growth parameters <50th percentile, termed: "rapid riser", "gradual riser", "always low". FEV1pp at age six was highest for the Always High trajectory. The Always Low trajectory was nearly 10% lower than the Always High trajectory. Sex, ethnicity, newborn screening and pancreatic function were associated with trajectory class membership.

CONCLUSIONS

Distinct early life growth trajectories were identified within CF. Trajectories that met CFF nutritional guideline recommendations were associated with higher FEV1pp at age six. CF care teams should continue to partner with families to encourage interventions to support optimal growth to improve lung function in CF.

Maternal vitamin D3 supplementation during the third trimester of pregnancy: effects on infant growth in a longitudinal follow-up study in Bangladesh

OBJECTIVE

To estimate the effects of prenatal vitamin D supplementation on infant growth in Dhaka, Bangladesh.

STUDY DESIGN

Longitudinal follow-up of infants born at term or late preterm (≥34 weeks) to participants in a randomized double-blind trial of maternal third-trimester vitamin D3 (35 000 IU/wk; vitamin D ) vs placebo. Anthropometry was performed at birth, 1, 2, 4, 6, 9, and 12 months of age. The primary analysis (n = 145 overall; n = 134 at 1 year) was a comparison of mean length-for-age z-score (LAZ) based on World Health Organization standards.

RESULTS

LAZ was similar between groups at birth, but 0.44 (95% CI, 0.06-0.82) higher in vitamin D vs placebo at 1 year, corresponding to a sex-adjusted increase of 1.1 cm (95% CI, 0.06-2.0). Mean change in LAZ from birth to 1 month was significantly greater in vitamin D (0.53 per month) vs placebo (0.19 per month; P = .004); but there was no significant divergence thereafter. In longitudinal (repeated-measures) analysis, average LAZ during infancy was 0.41 higher in vitamin D vs placebo (95% CI, 0.11-0.71, P = .01). Stunting was less common in vitamin D (17% of infants were ever stunted) vs placebo (31%; P = .049). Other anthropometric indices were similar between groups.

CONCLUSIONS

Maternal vitamin D3 supplementation (35 000 IU/wk) during the third trimester of pregnancy enhanced early postnatal linear growth in a cohort of infants in Bangladesh.