Lower Birth Weight, Multiple Birth, and Preterm Delivery Treatment

Lower Birth Weight, Multiple Birth, and Preterm Delivery Treatment 

Introduction: The increasing proportion of births to women aged 35 years and older raises the question of how delayed childbirth impacts birth outcome (low birth weight [LBW], preterm delivery, and fetal growth restriction). The effects of delayed childbearing in women over age 35 years on population rate changes in LBW (below 2500 g), preterm delivery (less than 37 weeks gestation), multiple births, and small for gestational age (SGA; below the 10th percentile) were examined.

Methods: Population health data were obtained from the provincial Notification of Birth regarding all live or stillborn deliveries in Alberta, Canada between 1990 and 1996 (42,930 and 37,710 births, respectively). The data included information concerning maternal and infant factors. Data were stratified according to birth weight, gestational age at delivery, and multiple pregnancies. The SGA values were determined, based on recent Alberta data. Data regarding birth weight and gestational ages of infants conceived by in vitro fertilization were obtained from the Regional Fertility Program. Potential confounding attributable to in vitro fertilization was examined.

Results: The proportion of births to women aged 35 years and older rose 51.2% from 8.4% in 1990 to 12.6% in 1996. Among these women, the rate of LBW deliveries rose 11% and preterm delivery rose 14%. Delayed childbirth was responsible for 78% of the change in LBW in the population and 36% of the changes in the incidence of preterm delivery. Provincial multiple birth rates rose by 15% for twins and 14% for triplets. Delayed childbearing was responsible for 15% of the rise in the rate of twins and 69% of the increase in triplets. After excluding in vitro fertilization, the change was 43% preterm rates, 100% for LBW, 14% for twins, and 9% for triplets. Delayed childbearing did not impact the rate of singleton SGA deliveries.

Conclusion: The recent rise in LBW and preterm delivery is partially caused by the population phenomenon of delayed childbearing. Maternal age was not associated with changes in SGA. Prospective parents need to be aware of the higher risk for neonatal morbidity with delayed childbearing. The impact of delayed childbearing on health care resources is important information for health care providers.