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Show bacterial vaginal infections, bacteriuria, sexually transmitted diseases, cervical and uterine malformations, and diseases of pregnancy, but many have no identified cause. In Utah in 1997, 98.9 per 1,000 live births were preterm (before 36 completed weeks of gestation). Preterm live births have increased from 87.4 per 1,000 live births in 1989 to 98.9 per 1,000 live births in 1997. Each gestational age category of preterm births has experienced an increased incidence since 1989. Short interpregnancy intervals have been associated with poor pregnancy outcomes (Klerman, Oliver & Goldenberg, 1998).In fact, the shorter the interval between pregnancies, the greater the likelihood of premature delivery. Incidence of premature deliveries was lowest among women with intervals of 12 to 24 months between pregnancies (interval between delivery of one pregnancy and conception of the next). Utah data show similar findings in that infants conceived 18-23 months after a live birth had the lowest risks of low birth weight, preterm birth and small size for gestational age (Zhu, Rolfs Nangle & Horan, 1999). Figure 3 illustrates Utah data as they relate to interpregnancy spacing and outcomes of pregnancy. Figure 3: Comparison of Percentages of Low Birth Weight and Preterm Births by Intervals between Pregnancies, 1989-1997, Utah Source: Bao-Ping Zhu, unpublished manuscript presented at the Population Studies Seminar, Department of Sociology, University of Utah, March 4, 1998. ve Births 10-1 8- 9.3 -1 6 -?-LBW geo 4 6.9 ^^-~^_ ------ ^---------------------- ---#5.1 -•- Preterm Percenta 2 -0 - 4.1 0-5 6-17 Months Between Pregnancies 18-23 Utah data indicate that women who have previously given birth to a low birth weight infant are more likely to have another. Birth certificate data from Utah deliveries occurring between 1989-1996 were analyzed to examine the risk for low birth weight based on pregnancy history of the birth immediately prior to the one analyzed. Births were classified into low birth weight or normal weight categories. The chances of a woman having a second low birth weight infant after having had a low birth weight infant in their last pregnancy were 36% compared to only 4% among women who had not had a low birth weight infant in their last pregnancy. In examining the chances of a third low birth weight infant after a second, the chances increased to 43% compared to only 5% for women who had not had a low birth weight infant in their second pregnancy during the study period (Bureau of Vital Records, 1999a). Utah data reveal that women who themselves were born preterm have a higher risk of giving birth prematurely (Porter, Fraser, Hunter et al., 1997). Women who were born before 37 weeks of gestation were found to have a 20% greater risk for preterm delivery of their offspring. Offspring of women who themselves were born preterm were more likely to be born at earlier gestations than offspring of women who were born at 38 weeks' gestation or later. Risk of preterm birth increased with decreasing maternal gestational age, more than doubling for those women born before 32 weeks. Behavioral & Environmental Risks Tobacco use during pregnancy is associated with adverse pregnancy outcomes. The risk for low birth weight is compounded by the number of cigarettes smoked daily during pregnancy (National Center for Health Statistics, 1998). Nationally, in 1996, 13.6% of women reported tobacco use during pregnancy (National Center for Health Statistics, (1998) compared to 9.4% of mothers in Utah (Bureau of Vital Records, 1999a). Nationally, 12.1% of infants born to smokers were low birth weight compared to 6.9% for nonsmokers. Utah data for the period of 1989-1997 indicate that 12.5% of women 43 |
