Neonatal Assessment Calculator

Three of the assessments used most often in the delivery room and the nursery. Pick one from the first dropdown; the calculator only reads the inputs belonging to whichever you chose.

APGAR score

Developed in 1952 by Virginia Apgar, this five-sign system scores a newborn at 1 and 5 minutes after birth. Each sign scores 0 to 2, for a total out of 10. The five are Activity (muscle tone), Pulse (heart rate), Grimace (reflex irritability), Appearance (skin color), and Respiration, which spell out her surname.

7 to 10 is reassuring. 4 to 6 signals moderate concern and usually prompts assistance with breathing. 0 to 3 needs immediate intervention.

The 1-minute score reflects intrauterine conditions and the transition to breathing air. The 5-minute score is the one that carries prognostic weight, and a 5-minute score below 7 is associated with a higher risk of hypoxic-ischemic encephalopathy. Because those two readings mean different things, this calculator asks which one you are scoring and interprets accordingly.

One caution the original paper made and everyone forgets: APGAR was never designed to predict individual neurological outcome, and a single low score in an otherwise well baby means much less than the number suggests.

Gestational age from LMP

Naegele’s rule dates a pregnancy from the first day of the last menstrual period: estimated due date = LMP + 280 days, which is the same as adding 9 months and 7 days. Gestational age is always counted from that first day, not from conception, which is roughly two weeks later. The due date does not move as the pregnancy progresses, so this calculator reports days remaining rather than recalculating a due date.

The ACOG terminology, revised in 2013 and worth using because the old “term” bucket hid real differences in outcome:

Naegele’s rule assumes a 28-day cycle with ovulation on day 14. For anyone whose cycle runs longer or shorter, a first-trimester ultrasound is more accurate and is what dating is normally corrected to.

Birth weight percentile

Birth weight is classified against gestational age. Above the 90th percentile is LGA (large for gestational age), below the 10th is SGA (small for gestational age), and in between is AGA (appropriate for gestational age).

The reference values here come from the Fenton 2013 growth charts, which are sex-specific, so this calculator asks for the baby’s sex. Boys run roughly 100 to 150 g heavier than girls at the same gestational age, which is enough to move a borderline baby across the 10th percentile line. The table covers 26 through 42 weeks so preterm infants can actually be assessed, which is the situation these charts were built for in the first place.

For educational use. Clinical decisions need direct assessment and the full charts, not a lookup table.