DOES OUTCOME OF THE PREVIOUS PREGNANCY AFFECT LENGTH OF INTERVAL TO THE SUBSEQUENT PREGNANCY? † 1600

Abstract

Short interpregnancy intervals are associated with higher risks of adverse pregnancy outcomes such as low (<2.5 kg) and very low (<1.5 kg) birth weight. We hypothesized that outcome of the previous pregnancy might affect length of the interval to the next pregnancy and delivery (INTERVAL) such that if the outcome of previous pregnancy is a live birth, INTERVAL may be longer than if the outcome of last pregnancy were an abortion or stillbirth. We used the National Center for Health Statistics 1988 Linked Infant Birth and Death data for African American and White mothers with a previous pregnancy(N=1,931,592) to investigate this hypothesis. INTERVAL was reported as an ordinal categorical variable: 1-11, 12-17, 18-23, 24-35, 36-47, 48-59 and 60+ months. Among White mothers, there was no significant association between the outcome of previous pregnancy and INTERVAL [Mean Score Statistic(Mantel-Haenszel) chi-square, p=0.244]. On the other hand, among African American mothers, there was a significant association between the outcome of previous pregnancy and INTERVAL (p=0.015). Compared with African American mothers whose previous pregnancy terminated in a live birth, African American mothers whose previous pregnancy terminated in an outcome other than a live birth had a 50% increase in the risk for having a short (<18 months) INTERVAL (Relative Risk: 1.53, 95% C.I., 1.08-2.17).Table