Young maternal age and parity. Influences on pregnancy outcome.

The influence of very young maternal age and parity on pregnancy outcome was examined in a cohort of nearly 900 adolescents and mature women from Camden, New Jersey. Young primigravid primiparas (aged 12 to 15 years) were compared with mature primigravid primiparas (18 to 29 years). Young multiparas (19 years or younger, with a first pregnancy at the age of 12 to 15 years) were compared with mature, multiparas (19 to 29 years old, with a first pregnancy at 18 years or older). After controlling for confounding factors, young primiparas were found to have a modest increase in preterm delivery, which was not statistically significant. However, low gynecologic age contributed disproportionately to the risk of preterm delivery in this group, with risk decreasing with each year from menarche (Cox's proportional hazard, 0.80; 95% confidence interval [CI], 0.68 to 0.94). Among multiparas, there were several statistical interactions associated with increased risk of small-for-gestational-age infants, including interactions between young age and low pre-pregnancy body mass (adjusted odds ratio [AOR], 5.74; 95% CI, 2.18 to 15.08), young age and a prior low-birth-weight infant (AOR, 10.58; 95% CI, 3.89 to 28.77), and young age and a prior preterm delivery (AOR, 5.52; 95% CI, 2.04 to 14.98). Thus, while chronologic age per se may not be a good predictor of pregnancy outcome, adolescents remain a high-risk group because of factors that are more common among them (e.g., biologic immaturity, inadequate prenatal care, poverty, minority status, low prepregnancy weight) and because factors associated with an early adolescent pregnancy, such as low gynecologic age, may continue to influence the outcome of subsequent pregnancies.