sitar (version 1.0.4)

ukwhopt: UK-WHO growth reference including preterm

Description

The UK 1990 revised growth reference (Cole et al 2011) for birth length, weight and head circumference, fitted by the LMS method and summarised by values of L, M and S by sex from 23 to 42 weeks gestation.

Usage

data(ukwhopt)

source

The values are tabulated in the Excel spreadsheet UK_WHO_preterm.xls provided with the Excel add-in LMSgrowth from http://www.healthforallchildren.com/?product_cat=software.

Details

The growth reference is the birth section of the UK-WHO growth reference (see Wright et al 2010).

The L, M and S values for each measurement correspond respectively to the Box-Cox power, median and coefficient of variation of the distribution by age and sex (Cole & Green 1992). The short names for each measurement (see LMS2z) are as follows: height (ht), weight (wt) and head circumference (head).

Age is measured in weeks gestation and years post-term, where 0 years corresponds to 40 weeks gestation.

References

Cole TJ, Green PJ. Smoothing reference centile curves: the LMS method and penalized likelihood. Stat Med 1992;11:1305-19.

Cole TJ, Williams AF, Wright CM, et al. Revised birth centiles for weight, length and head circumference in the UK-WHO growth charts. Ann Hum Biol 2011;38:7-11.

Wright CM, Williams AF, Elliman D, et al. Using the new UK-WHO growth charts. BMJ 2010;-340:c1140.

Examples

data(ukwhopt)
## calculate median birth weight in girls from 23 to 42 weeks gestation
LMS2z(x = (23:42-40) * 7 / 365.25, y = 0, sex = 2, measure = 'wt', ref = 'ukwhopt', toz = FALSE)