Estimate gestational age using INTERGROWTH-21st predictive equations

Estimate gestational age using INTERGROWTH-21^st predictive equations

Usage

ig_fet_estimate_ga(crl_mm = NULL, headcirc_mm = NULL, femurlen_mm = NULL)

Arguments

crl_mm: Numeric vector with crown-rump length value(s) in mm taken from an ultrasound scan obtained 56 to 97 days since the last menstrual period. If not NULL (the default), should be of length one or the same length as other inputs. The function will return NA for all elements of crl_mm which are not between 15 and 95 mm and have no headcirc_mm or abdocirc_mm values.
headcirc_mm: Numeric vector with head circumference value(s) in cm taken from an ultrasound scan obtained 98 to 181 days since the last menstrual period. If not NULL (the default), should have length one or same length as other inputs.
femurlen_mm: Numeric vector with femur length value(s) in cm. If not NULL (the default), should have length one or same length as other arguments inputs.

Value

A numeric vector with estimated gestational ages in days. This vector will have a length equal to the outputs from vctrs::vec_recycle_common().

Note

Vector inputs to this function are recycled using vctrs::vec_recycle_common(). The function will attempt to estimate the gestational age (GA) in three steps, from highest to lowest accuracy. First, using crown-rump length measurements obtained in early pregnancy, then with both head circumference and femur length measurements, and finally with head circumference alone.

References

Papageorghiou AT, Kennedy SH, Salomon LJ, Ohuma EO, Cheikh Ismail L, Barros FC et al. International standards for early fetal size and pregnancy dating based on ultrasound measurement of crown-rump length in the first trimester of pregnancy. Ultrasound Obstet Gynecol 2014, 44(6):641-48 doi:10.1002/uog.13448

Papageorghiou AT, Kemp B, Stones W, Ohuma EO, Kennedy SH, Purwar M et al. Ultrasound-based gestational age estimation in late pregnancy. Ultrasound Obstet Gynecol 2016. 48(6):719-26 doi:10.1002/uog.15894

Examples

# Estimate gestational age in days using crown-rump length (most accurate)
ig_fet_estimate_ga(crl_mm = 40:45)
#> [1] 75.20116 75.80278 76.40134 76.99695 77.58970 78.17970

# Estimate gestational age in days using head circumference and femur length
# (second-most accurate)
ig_fet_estimate_ga(headcirc_mm = 250:255, femurlen_mm = 55:60)
#> [1] 200.5229 202.7155 204.9335 207.1772 209.4469 211.7429

# Estimate gestational age in days using head circumference only (least
# accurate)
ig_fet_estimate_ga(headcirc_mm = 250:255)
#> [1] 189.8030 190.5331 191.2662 192.0023 192.7416 193.4839

# The function defaults to CRL if available
ig_fet_estimate_ga(crl_mm = 40:45,
                   headcirc_mm = 250:255,
                   femurlen_mm = 55:60)
#> [1] 75.20116 75.80278 76.40134 76.99695 77.58970 78.17970

# Inputs are recycled using [vctrs::vec_recycle_common]
ig_fet_estimate_ga(headcirc_mm = 252,
                   femurlen_mm = 55:60)
#> [1] 201.2413 203.0790 204.9335 206.8049 208.6934 210.5992