Abstract 1514 Poster Session III, Monday, 5/3 (poster 55)

IVF has been faulted for contributing to the increased prevalence of low birth weight infants. It is known the IVF pregnancies are at increased risk of multiple birth, low birth weight (LBW) and preterm delivery. However, the impact of IVF on the population prevalence of LBW and preterm delivery is ill defined. For the past 3 years the LBW and preterm rates in Alberta have steadily increased raising concern that such increases are related to IVF.

Purpose: To quantify the contribution of IVF on LBW, preterm delivery and multiple birth in a population.

Methods: Data on successful IVF pregnancies between 1994-1996 were obtained from the Alberta Regional Fertility program. Data were analyzed with regard to changes in low birth weight (<2500 grams) and preterm delivery (< 37 weeks).

Results: The number of successful IVF pregnancies increased by 30.0% between 1994-1996 from 80 to 104. The proportion of IVF infants born at LBW increased between 1994 and 1996 from 23.8% to 39.0% (p=0.005). During that time, provincial rates of LBW increased from 6.1% to 6.5% (p=0.02), a 6.7% increase. The IVF component of this 6.7% increase in LBW was 19.1%. IVF preterm rates increased from 47.5% to 52.9% over 3 years. During this time, population preterm rates increased by 7.6% from 7.3% to 7.8%. IVF accounted for 24.0% of the 7.6% increase. Multiple birth rates also increased. The population increase in twin births was 4.93 % and IVF twins accounted for 28.1% of this. The population increase in triplet births was 30.0% and IVF accounted for 95.0% of this.

Conclusion: Approximately 20.0% of the observed increase in LBW and preterm delivery in a province of 2.5 million was due to IVF. Furthermore, IVF was a major contributor to increases in multiple birth rate.