Increase in low-birth-weight infants in Japan and associated risk factors, 1980-2000

Area of Science:

• Perinatal epidemiology
• Public health research
• Maternal and child health

Background:

• The prevalence of low-birth-weight (LBW) infants has been rising in Japan.
• Understanding the contributing factors to LBW is crucial for public health interventions.

Purpose of the Study:

• To investigate the factors associated with the increasing prevalence of low-birth-weight (LBW) infants in Japan.
• To identify key determinants driving the trend in LBW rates.

Main Methods:

• Analysis of a large dataset (11,746 infants) from the Children and Infant Growth Surveys (1980, 1990, 2000).
• Multivariate logistic regression was employed to identify independent risk factors for LBW between 1990 and 2000.
• Population attributable fractions (PAF) were calculated for significant factors.

Main Results:

• LBW infant proportion increased from 4.2% (1980) to 8.3% (2000).
• Independent risk factors for LBW included preterm delivery, early term delivery, female infant sex, primiparity, multiple gestation, short maternal stature, older maternal age, and maternal smoking.
• Preterm/early term delivery and multiple gestations accounted for over 85% of LBW cases.

Conclusions:

• The rise in LBW infants in Japan is primarily attributed to increased preterm deliveries and multiple gestations.
• While maternal smoking prevalence increased, its association with the rise in LBW was not substantial.
• Targeting interventions for preterm birth and multiple gestations is essential to curb LBW trends.