Abstract 1513 Poster Session III, Monday, 5/3 (poster 54)

Both advanced maternal age and IVF have independently been related to an increased risk of multiple birth, low birth weight and preterm delivery however, little has been described about the potential additive or multiplicative effect of age and IVF.

Purpose: To evaluate the relationship between maternal age and multiple birth, preterm delivery and low birth weight in an IVF population as compared with population proportions in the same age groups for the same variables.

Methods: Data from the Alberta Regional Fertility Clinic were retrospectively reviewed from 1994-1997 and compared to provincial population data.

Results: Age data were available on 76.0% of women (446/584) who conceived through IVF. Mean maternal age among those who conceived through IVF was 34 years (SD 3.46). The IVF multiple birth rate was 28.9%. The proportion of women under 30 who had twins was 27.1% compared to 26.1% and 19.6% for women age 30-34 and 35 and over respectively (not significant). The proportion of women under 30 who had triplets was 10.2% which compared to 6.9% and 6.5% of those aged 30-34 and 35 and over respectively (not significant). There was no overall increase in the risk of multiple birth for the youngest compared to oldest age group (OR = 0.59, 95% CI 0.32-1.12). The risk of preterm delivery among IVF women did not change over age group, however, the risk of low birth weight was significantly higher among younger women (p=0.04). By comparison, population data on 114,000 women revealed that, with increased maternal age there were significantly increased risks of: multiple birth (p<0.001), preterm delivery (p<0.001)and low birth weight (p<0.001).

Compared to three years of provincial data (population 2.5 million), IVF infants were more likely to be multiples (28.9% vs. 2.3%), to have older moms (28 vs 34 yrs), to be low birth weight(23.3% vs. 6.4%) and to be preterm (37.7% vs 7.5%).

Conclusion: Although IVF pregnancies were associated with substantially increased risks of multiple birth this risk was not compounded by maternal age. Furthermore, among the IVF population, those over 35 were at not at an increased risk of preterm delivery or low birth weight. The elevated risks of preterm delivery and low birth weight among younger IVF moms may be associated with the increased likelihood of multiple birth.