Neonatal Gestational Age Calculator

This calculator provides a simplified, physical-maturity-only estimate of gestational age, inspired by the physical maturity component of the New Ballard Score, the well-known bedside newborn maturity assessment published by Ballard et al. in 1991 (an expansion of the original Ballard Score to reliably cover extremely premature infants). The real New Ballard Score combines two separate halves -- six physical maturity signs (skin, lanugo, plantar surface, breast, eye/ear, genitals) plus six neuromuscular maturity signs (posture, arm recoil, popliteal angle, and others) -- and maps their combined total to a gestational-age estimate. This calculator implements only the physical maturity half: Skin, Lanugo, Plantar Surface, Breast, Ear/Eye, and Genitals are each scored 1 (least mature) to 5 (most mature) against real Ballard Score descriptors, summed into Physical Maturity Score, and converted to Estimated Gestational Age using a simplified linear approximation. Because it omits the neuromuscular maturity examination entirely, its result is a rougher estimate than a full clinical Ballard assessment, and it should not be treated as a substitute for one.

Every one of the six physical criteria contributes equally to the total -- a one-point change in any single criterion moves Physical Maturity Score, and therefore Estimated Gestational Age, by the same amount as a one-point change in any other criterion. The real Ballard Score's Genitals criterion is actually two SEPARATE sets of descriptors -- one for male anatomy, one for female -- rather than one generic scale; this calculator uses a single 1-5 Genitals input with BOTH descriptor sets shown side by side in its help text as a simplification, so score against whichever set matches the newborn's anatomy rather than treating the input as sex-neutral. This calculator's Physical Maturity Score has its own floor at 0 (every criterion scored at its least-mature level "1"), which puts a hard floor of 24 weeks on Estimated Gestational Age -- that floor is a limit of this simplified scale, not evidence the newborn is exactly 24 weeks, and Assessment Floor Reached flags it explicitly rather than silently reporting 24 weeks as if it were a precise reading. In real newborn care, gestational age is primarily established from obstetric dating (last menstrual period and early ultrasound) whenever that's available; a physical maturity exam like this one is used to confirm or estimate gestational age when reliable dating is not available, or when the newborn's physical findings unexpectedly diverge from the stated gestational age.