PTwins {PTwins}

Percentile Estimation of Fetal Weight for Twins by Chorionicity

Description

The PTwins function estimates the fetus weight percentile using a multilevel linear model developed from a Spanish twin cohort.

Usage

PTwins(weight,week,day=3,dichorionic=TRUE)

Arguments

weight

The fetus weight estimated by ultrasound at a gestational age (weeks) using Hadlock formula:

log10(FW)=1.3596-0.00386(AC)x(FL)+0.0064(HC)+0.0006(BPD)x(AC)+ 0.0424(AC)+0.174(FL)

FW: fetal weight, AC: abdominal circumference, FL: femur lenght,

HC: head circumference, BPD: biparital diameter

week

The gestational age in weeks for which the Fetus weight where estimated

day

The exact day in the gestational week at which the fetus weight were estimated. For the percentile calculation, if we choose for example: week=23, day=2, this is equivalent to 163 days of GA

dichorionic

This parameter indicates if the fetus is dichorionic-diamniotic (dichorionic=TRUE) or monochorionic-monoamniotic (dichorionic=FALSE)

Details

The inputs weight, week, day or dichorionic can be a number or a vector to include several cases

Value

The returned fit object of PTwins contains the following components.

Percentile

Percentile of the fetus weight

weight

fetus weight

GA

Gestational age in exact weeks

Author(s)

Rocio Aznar, Luis Mariano Esteban, Gerardo Sanz, Ricardo Saviron

Examples

#Percentile estimation of a dichorionic-diamniotic fetus of 2300 grams
#of weight estimated at the 22nd week (+2 days) of gestational age.

PTwins(weight=2300,week=22,day=2,dichorionic=TRUE)

#Percentile estimation of a monochorionic-diamniotic fetus of 2300 grams
#of weight estimated at the 22nd week (+2 days) of gestational age.

PTwins(weight=2300,week=22,day=2,dichorionic=FALSE)

#Percentile estimation of a dataframe that includes 10 cases

WEIGHT<-round(rnorm(10,2100,125),digits=0)
WEEK<-sample(seq(18,36),10)
DAY<-sample(seq(0,7),10,replace=TRUE)
dichorionic<-sample(c("TRUE","FALSE"),10,replace=TRUE)
DT<-data.frame(WEIGHT,WEEK,DAY,dichorionic)

PTwins(weight=DT$WEIGHT,week=DT$WEEK,day=DT$DAY,dichorionic=DT$dichorionic)