ukwhopt {sitar}

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

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).

Source

The values are tabulated in the Excel spreadsheet UK_WHO_preterm.xls provided with the Excel add-in LMSgrowth from https://www.healthforallchildren.com/shop-base/software/lmsgrowth/

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 (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)