Preterm Birth Causes, Consequences, and Prevention (2007) / Chapter Skim
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5 Medical and Pregnancy Conditions Associated with Preterm Birth
5 Medical and Pregnancy Conditions Associated with Preterm Birth
Pages 148-168
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From page 148... ...
Finally, the number of American women using assisted reproductive technologies to achieve pregnancies has increased, and the use of such technologies is associated with mul tiple gestations and the increased risk for preterm delivery. The existence of any of these risk factors for preterm birth provides a focus for understanding their causative effects and developing in terventions.
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From page 149... ...
This chapter discusses several medical illnesses and conditions, such as low prepregnancy weight, obesity, a family history of spontaneous preterm birth, and short interpregnancy interval, and their relationships to preterm birth. The chapter also provides an overview of infertility treatments and the resulting risk of multiple gestations, which place women at a greater risk for preterm delivery.
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From page 150... ...
The mechanism(s) that place a woman at increased risk for preeclampsia are unknown.
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From page 151... ...
After adjusting for confounders (previous preterm labor, previous low birth weight, standing at work >2 hours, abruptio placentae, urinary tract infection and stress score >5) , Moutquin (2003)
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From page 152... ...
Short Interpregnancy Interval and Preterm Birth Interpregnancy interval is defined as that interval between the termination of one pregnancy and the conception of another. Numerous investigators have found a univariate association between short interpregnancy interval and a number of adverse perinatal outcomes, including preterm birth, low birth weight, and stillbirth (Adams et al., 1997; Al-Jasmi et al., 2002; Basso et al., 1998; Blackmore-Prince et al., 2000; Brody and Bracken, 1987; Conde-Agudelo et al., 2005; Dafopoulos et al., 2002; Ekwo and Moawad,
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From page 153... ...
The definition of short interpregnancy interval varies widely across studies; the most common definition is less than or equal to 6 months. Impacts of Ethnicity and Geography The relationships between short interpregnancy interval and preterm birth, low birth weight, and small-for-gestational age birth have been noted to be similar in magnitude and significance for African American and white women (James et al., 1999; Kallan, 1992, 1997; Zhu et al., 2001)
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From page 154... ...
In recent years, an unintended consequence of the use of these technologies, multiple gestations and the increased risk for preterm delivery, has become a focus of attention. There is also evidence that a portion of the reported association between infertility treatments and preterm birth may be attributable to the underlying biological reasons for infertility and subfecundity (long time to becoming pregnant)
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From page 155... ...
for preterm delivery (95% CI .8–2.1) in both cohorts.
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From page 156... ...
156 PRETERM BIRTH Fresh nondonor 14.2% Frozen nondonor 8.0% Fresh donor 3.6% Frozen donor 0.1% New treatment 74.1% procedure FIGURE 5-1 Types of ART procedures used in the United States, 2003.
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From page 157... ...
157 MEDICAL AND PREGNANCY CONDITIONS FIGURE 5-3 Numbers of ART cycles performed, live-birth deliveries, and infants born as a result of the use of ARTs, 1996 to 2003.
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From page 158... ...
Continued research to understand disparities in infertility, infertility treatment, and outcomes of treatment including multiple gestations and preterm birth is needed.
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From page 159... ...
Fiftythree percent of 45,751 infants born in the United States as a result of the use of ART in 2002 were part of multiple gestations. Although approximately 1 percent of the infants born were conceived through the use of ARTs, these infants represented 0.5 percent of all singleton births and 17 percent of all multiple births.
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From page 160... ...
Much less attention has been paid to the role of ovulation promotion (superovulation or intrauterine insemination and conventional ovulation induction) , which is equally important in terms of its contribution to multiple gestations.
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From page 161... ...
Finding 5-1: The prevalence of the use of superovulation with or without artificial insemination is unknown, and no systematic mechanisms are in place to collect these data. ARTs and Preterm Birth The primary concern regarding the use of ARTs and ovulation promotion is the risk of preterm delivery that is associated with multiple gestations.
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From page 162... ...
. A meta-analysis that compiled information from 12,283 singleton births conceived through the use of IVF and 1.9 million spontaneously conceived singleton births noted a twofold increase in the risk of preterm delivery (Jackson et al., 2004)
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From page 163... ...
The study also found that both women who had undergone IVF and subfertile women did not have an increased risk for endometrial cancer. The authors suggest a potential link between endometrial cancer and subfertility.
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From page 164... ...
Concern has been raised about the use of intracytoplasmic sperm injection, as this procedure impedes the ovum's natural ability to resist fertilization by a sperm that would otherwise not have the ability to fertilize the egg. However, these risks are considered small, and the greater risk from the use of these procedures results from the consequences of multiple gestations.
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From page 165... ...
165 MEDICAL AND PREGNANCY CONDITIONS 8,000 200 High-Order Number High-Order Rate Rate per 100,000 live births 6,000 150 Number of live births 4,000 100 2,000 50 0 0 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91 '92 '93 '94 '95 '96 '97 '98 '99 '00 '01 '02 FIGURE 5-8 Trends in live high-order births, 1980 to 2002, United States.
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From page 166... ...
Despite the successes in reducing the rates of higher-order multiple births, the United States does not fare as well as European countries in minimizing the risk of multiple gestations (Anderson et al., 2005)
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From page 167... ...
. Currently, public funding of ART cycles in Sweden covers only the transfer of single embryos, which has resulted in an even further reduction in multiple gestations.
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From page 168... ...
168 PRETERM BIRTH nancy rates did not differ. Twin pregnancies were reduced from 19 percent to 3 percent (Gordts et al., 2005)
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