ukwhopt: UK-WHO growth reference including preterm

Description

The UK-WHO growth reference for height, weight, BMI and head circumference (see Wright et al 2010), fitted by the LMS method and summarised by values of L, M and S by sex from 26 weeks gestation to 20 years.

Usage

ukwhopt

Arguments

Format

A tibble with 542 observations on the following 17 variables:

age_wm: numeric vector - age in weeks or months - see wm
wm: three-level factor indicating weeks or months: wkga = gestational weeks, wk = postnatal weeks, mth = postnatal months
years: numeric vector - age in years
L.ht: numeric vector
M.ht: numeric vector
S.ht: numeric vector
L.wt: numeric vector
M.wt: numeric vector
S.wt: numeric vector
L.bmi: numeric vector
M.bmi: numeric vector
S.bmi: numeric vector
L.head: numeric vector
M.head: numeric vector
S.head: numeric vector
origin: two-level factor indicating the provenance of the data, with levels British1990 and WHO2006
sex: two-level factor with level 1 male and level 2 female

Details

The growth reference combines the birth section of the British 1990 growth reference (Cole et al 2011) from 26 to 42 weeks gestation, the WHO growth standard from 2 postnatal weeks to 4 years, and the British 1990 reference from 4 to 20 years.

Age is measured in years, where 40 weeks gestation is 0 years. The conversion from weeks gestation to years is: years = (weeks - 40) * 7 / 365.25.

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 measurement short names and units (see LMS2z) are as follows: height (ht, cm), weight (wt, kg), BMI (bmi, kg/m2) and head circumference (head, cm).

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

Run this code

data(ukwhopt)
## calculate median birth weight (kg) in girls from 26 to 44 weeks gestation
v <- LMS2z(x = (26:44-40) * 7 / 365.25, y = 0, sex = 2, measure = 'wt',
  ref = 'ukwhopt', toz = FALSE)
setNames(v, 26:44)

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