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Swedish intrauterine growth reference ranges for estimated fetal weight
Linda Lindström1, Mårten Ageheim2, Ove Axelsson2,3
1Department of Women's and Children's Health, Uppsala University, Uppsala, Sweden. linda.lindstrom@kbh.uu.se.
Insights
Updated Swedish fetal weight reference ranges are now available for improved assessment of fetal growth and preterm infant development. These new standards offer a more accurate evaluation from 12 to 42 weeks gestation.
Area of Science:
- Obstetrics and Gynecology
- Perinatal Medicine
- Fetal Development
Background:
- Fetal growth restriction is a significant risk factor for adverse perinatal outcomes.
- Accurate fetal weight standards are crucial for assessing fetal growth and postnatal development, especially in preterm infants.
Purpose of the Study:
- To establish updated Swedish reference ranges for estimated fetal weight (EFW) from 12 to 42 weeks gestation.
- To provide reliable standards for evaluating intrauterine fetal growth and early postnatal growth in preterm infants.
Main Methods:
- Prospective longitudinal multicentre study of 583 women.
- Utilized Hadlock's 3rd formula for estimated fetal weight (EFW) calculations.
- Employed a two-level hierarchical regression model to derive reference ranges.
Main Results:
- Developed new Swedish reference ranges for EFW from 12-42 weeks gestation.
- Observed higher EFW in males compared to females.
- New ranges showed higher EFW from week 33 compared to current Swedish ranges and from week 24 compared to INTERGROWTH-21st ranges.
Conclusions:
- The updated Swedish reference ranges provide a more accurate tool for assessing fetal weight and growth.
- These new standards are valuable for both intrauterine assessment and evaluating early postnatal growth in preterm infants.
- The findings support improved clinical management of fetal growth and perinatal outcomes.
Abstract:
Fetal growth restriction is a strong risk factor for perinatal morbidity and mortality. Reliable standards are indispensable, both to assess fetal growth and to evaluate birthweight and early postnatal growth in infants born preterm. The aim of this study was to create updated Swedish reference ranges for estimated fetal weight (EFW) from gestational week 12-42. This prospective longitudinal multicentre study included 583 women without known conditions causing aberrant fetal growth. Each woman was assigned a randomly selected protocol of five ultrasound scans from gestational week 12 + 3 to 41 + 6. Hadlock's 3rd formula was used to estimate fetal weight. A two-level hierarchical regression model was employed to calculate the expected median and variance, expressed in standard deviations and percentiles, for EFW. EFW was higher for males than females. The reference ranges were compared with the presently used Swedish, and international reference ranges. Our reference ranges had higher EFW than the presently used Swedish reference ranges from gestational week 33, and higher median, 2.5th and 97.5th percentiles from gestational week 24 compared with INTERGROWTH-21st. The new reference ranges can be used both for assessment of intrauterine fetal weight and growth, and early postnatal growth in children born preterm.
