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Growth retardation in preterm infants
Insights
Preterm infants are generally smaller than fetuses of the same gestational age. This study compared birth weights to estimated fetal weights using ultrasound, finding lower birth weights, particularly in early pregnancy and for female infants.
Area of Science:
- Perinatology
- Fetal Growth and Development
- Neonatal Studies
Background:
- Established relationships exist between birth weight and gestational age.
- Fetal weight estimation relies on ultrasound measurements like biparietal diameter (BPD) and abdominal diameter (AD).
- Previous research has not comprehensively compared preterm infant birth weights to contemporaneous intrauterine fetal weights.
Purpose of the Study:
- To determine if preterm infants, as a group, are smaller than fetuses at the same gestational age.
- To compare birth weight distributions with estimated intrauterine weight distributions.
- To analyze sex-specific differences in fetal growth and birth weight.
Main Methods:
- Utilized existing birth weight-for-gestational age charts from 3888 newborn infants.
- Estimated sex-specific intrauterine weight distributions using fetal BPD and AD ultrasound measurements.
- Compared birth weight data with estimated fetal weight data at specific gestational ages (223 and 258 days).
Main Results:
- Birth weights were consistently lower than estimated intrauterine weights across sexes and gestational ages studied.
- This discrepancy was more pronounced in earlier stages of gestation (e.g., 223 days).
- Female infants exhibited a greater difference between birth weight and estimated intrauterine weight compared to males.
Conclusions:
- Preterm infants tend to be smaller than fetuses of equivalent gestational age, indicating potential growth differences.
- Standard birth weight charts may underestimate fetal size, especially for females and earlier gestations.
- Findings highlight the importance of considering sex and gestational age when assessing fetal and neonatal growth.
Abstract:
This paper combines earlier results on the relation between birthweight and gestational age, and the relation between fetal weight and ultrasound measurements of the fetal biparietal diameter (BPD) and mean abdominal diameter (AD) to investigate whether preterm infants (viewed as a group) are smaller than unborn fetuses of the same gestational age. The birthweight distribution for each sex at 223 and 258 days gestation was derived from the birthweight-for-gestational age charts based on 3888 newborn infants. The sex-specific intrauterine weight distribution was estimated from ultrasound measurement of the fetal BPD and AD performed on randomly selected fetuses of gestational age 223 and 258 days. The birthweights were lower than the intrauterine weights, especially early in pregnancy and for female infants. Thus, the 10th birthweight centile for girls at day 223 corresponds to the 4th centile of the 'true' intrauterine weight, and the 'true' intrauterine 10th centile corresponds to the 25th centile birthweight at day 223.