Maternal age, gravidity, and pregnancy spacing effects on spontaneous fetal mortality.

Differentials in the probability of pregnancy loss are examined using pregnancy history data from eight WFS surveys in developing countries. Multiple logistic regression equations are estimated. The probability of loss varies substantially over the reproductive career. Both higher-order pregnancies and those conceived at older ages are more likely to terminate in loss. maternal age differentials are more pronounced for lower-order pregnancies. First and second pregnancies conceived over age thirty suffer especially high levels of loss. Pregnancies conceived relatively soon after the termination of the previous pregnancy are more likely to be lost, as are pregnancies conceived after long intervals. Risk of loss is higher for women previously experiencing loss, and the effect persists beyond the pregnancy following the loss.