INTERGROWTH-21st postnatal growth calculator for preterm infants (27 to 64 weeks)
Preterm infants, 27 to 64 weeks postmenstrual age: weight, length, head circumference and weight-for-length.
International standards for postnatal growth from healthy preterm infants born at 26 to 36 completed weeks (Villar 2015). Their medians merge with the WHO Child Growth Standards by 64 weeks. The authors describe them as standards for monitoring postnatal growth especially after 32 weeks.
Z-scores and centiles come from the INTERGROWTH-21st models: a normal distribution, with weight and length on the log scale.
Tips
- Enter the bare minimum:
- Can enter just sex, postmenstrual age, and growth metrics, without dates, if desired
- If only a postmenstrual age is entered, the 50th percentile values will be displayed
- If any dates are entered, the other dates and ages are calculated where possible
- Gestational age and dates can be calculated under Dates: LMP, due date, birth, day of life.
- Gestational age: weeks and days, e.g. 34 3/7 (34+3 also works)
- Weight: grams. For kilograms, enter e.g. 1.2kg; for pounds and ounces, e.g. 8-4 for 8 lb 4 oz
- Head circumference and length: cm. For inches, enter e.g. 20"
- Weight-for-length is calculated when both weight and length are entered.