Impact of maternal age on preterm delivery and low birthweight: a hospital-based collaborative study of nulliparous Lebanese women in Greater Beirut.

OBJECTIVES: To analyze the impact of maternal age at first childbirth on the incidence of preterm delivery and low birthweight among single live births delivered to nulliparous Lebanese women in Greater Beirut. STUDY DESIGN: Eligible subjects were selected from a consecutive sample of neonatal admissions to nine National Collaborative Perinatal Network participating hospitals over a three-year period (April 1, 1999 to March 31, 2002). Chi-square tests and logistic regression analyses were applied. RESULTS: Out of 5556 nulliparous mothers, 5.4% had a preterm delivery and 5.2% a low-birthweight infant. In the multivariate analysis, preterm delivery was not significantly affected by old maternal age. Mothers aged 25 years or more remained a high-risk group for low birthweight even after controlling for potentially confounding characteristics. CONCLUSIONS: Maternal age at first childbirth above 25 years is an independent risk factor for low birthweight, but not for preterm delivery, an outcome influenced mainly by obstetric complications.