School of Population Health

PhD candidate: Rajneeta Saraf


Research topic:

Neonatal vitamin D levels and respiratory tract infections in the first year of life


Associate Professor Cameron Grant  - Centre for Longitudinal Research
Associate Professor Susan Morton - Centre for Longitudinal Research


Rajneeta Saraf is a graduate of Victoria University of Wellington (Bachelor of Science and Bachelor of Biomedical Science), the University of the South Pacific and Fiji School of Medicine (Master of Microbiology & Public Health). Rajneeta is currently undertaking a PhD, which is being completed at the Centre for Longitudinal Research.

Rajneeta has considerable public health research experience in the Pacific. Immediately prior to commencing her doctoral studies, Rajneeta was employed as a Health Monitoring and Evaluation Officer for the International Planned Parenthood Federation- Sub Regional Office for the Pacific (Fiji). Rajneeta’s experience involved monitoring and evaluation of maternal and infant health programmes in nine Pacific countries, namely: Fiji, Samoa, Tonga, Kiribati, Tuvalu, Papua New Guinea, Solomon Islands and Vanuatu.

PhD project details:

Summary of issue:

Vitamin D deficiency has re-emerged as a prevalent public health issue in many countries. Vitamin D status at birth is determined by the mother’s vitamin D status during pregnancy. Vitamin D deficiency at birth and during early childhood appears to increase the risk of childhood respiratory infections. Respiratory infections are the leading cause of child death globally, and of hospital admission and primary care utilisation in the preschool age group.

Vitamin D concentrations in New Zealand during pregnancy and infancy are lower than in most developed countries. Hospital admission rates for respiratory infections in New Zealand are higher than in other developed countries. In New Zealand vitamin D status varies with ethnicity. Among young children in Auckland, those of Pacific ethnic groups are at highest risk of vitamin D deficiency. One quarter of Pacific children in Auckland <2 years old have a serum vitamin D concentration low enough to place them at risk of rickets. Pacific children are also the ethnic group in New Zealand with the highest hospital admission rates for respiratory infections.

Main research question:

Does poorer neonatal vitamin D status increase the risk that an infant will be hospitalised with a respiratory infection?

Summary of research:

Rajneeta’s project will be completed within Growing Up in New Zealand, New Zealand’s new birth cohort study at the Centre for Longitudinal Research. 6846 children born in 2009 and 2010 to women who, during their pregnancy, were residing within the Auckland, Counties-Manukau or Waikato District Health Board regions and living between the Waitemata harbour and Lake Taupo were enrolled into Growing Up. This region was chosen because of its ethnic and socioeconomic diversity. Enrolment occurred during the pregnancy.  

All children within Growing Up who have been hospitalised with a respiratory infection during infancy will be identified through linkage with hospital records. These case children will then be compared with a control group of Growing Up children who have not been hospitalised during infancy with a respiratory infection. The principle exposure of interest is vitamin D status at birth. Vitamin D status at birth will be determined by measuring 25-hydroxy-vitamin D, the main circulating form of vitamin D, on dried blood spots (Guthrie cards) collected at birth onto the newborn screening cards.

The project will determine if vitamin D status at birth is associated with hospitalisation for respiratory infections during infancy.


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