Who is at risk for prolonged and postterm pregnancy?

Department of Obstetrics and Gynecology, University of California, San Francisco, CA, USA.
American journal of obstetrics and gynecology (Impact Factor: 3.97). 05/2009; 200(6):683.e1-5. DOI: 10.1016/j.ajog.2009.02.034
Source: PubMed

ABSTRACT The objective of the study was to examine risk factors for postterm (gestational age >or= 42 weeks) or prolonged (gestational age >or= 41 weeks) pregnancy.
We conducted a retrospective cohort study of all term, singleton pregnancies delivered at a mature, managed care organization. The primary outcome measures were the rates of pregnancies greater than 41 or 42 weeks' gestation. Multivariable logistic regression models were used to control for potential confounding and interaction.
Specific risk factors for pregnancy beyond 41 weeks of gestation include obesity (adjusted odds ratio [aOR], 1.26; 95% confidence interval [CI], 1.16-1.37), nulliparity (aOR, 1.46; 95% CI 1.42-1.51), and maternal age 30-39 years (aOR, 1.06; 95% CI, 1.02-1.10) and 40 years or older (aOR, 1.07; 95% CI, 1.02-1.12). Additionally, African American, Latina, and Asian race/ethnicity were all associated with a lower risk of reaching 41 or 42 weeks of gestation.
Our findings suggest that there may be biological differences that underlie the risk for women to progress to 41 or 42 weeks of gestation. In particular, obesity is a modifiable risk factor and could potentially be prevented with prepregnancy or interpregnancy interventions.

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    ABSTRACT: Ethnic minorities/immigrant groups tend to have increased risk for preterm birth. Less is known about this risk in diverse immigrant groups, couples of mixed ethnic-origin and in relation to duration of residence. Data from the Swedish Medical Birth Register on 1,028,303 mothers who gave birth to 1,766,026 singleton live born infants (1982-2002), was linked to the Education and Total Population Registers. Immigrant parents were identified by country of birth. Risk of early preterm, late preterm and postterm birth was analyzed using multinomial logistic regression. Polish, Yugoslavian, Iranian, South Asian, East Asian and Sub-Saharan African parents, Swedish mothers who had children with non-Swedish fathers, and parents from two different immigrant groups had higher risk of early preterm birth [adjusted relative risk (RR) (95 % CI) 1.76 (1.24-2.50), 1.57 (1.31-1.87), 1.67 (1.30-2.14), 1.52 (1.07-2.16), 1.51 (1.08-2.10), 2.03 (1.32-3.12), 1.56 (1.45-1.67), and 1.55 (1.35-1.77) respectively] compared to Swedish-born parents. South Asian, Sub-Saharan African, and East Asian immigrants had a higher risk of late preterm birth compared to Swedish-born parents. North African and Middle Eastern, Somali, and Ethiopian/Eritrean groups had increased risk of postterm birth [adjusted RR 1.31 (1.16-1.47), 2.57 (2.31-2.86), 1.85 (1.67-2.04) respectively]. Adjustment for covariates did not substantially change associations. Immigrant mothers resident <3 years had higher risk for early preterm and postterm birth compared to residents >10 years [adjusted RR 1.46 (1.24-1.71) and 1.16 (1.11-1.23) respectively]. In addition to higher risk of preterm birth in select immigrant groups, some immigrant groups are also at higher risk of postterm birth. Shorter duration of residence is associated with higher risk of non-term deliveries.
    European Journal of Epidemiology 02/2015; DOI:10.1007/s10654-014-9986-0 · 5.15 Impact Factor
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    ABSTRACT: Background and objectives. Despite growing interest in the role of maternal psychosocial stress as a determinant of preterm birth, no existing work has examined the relation between maternal stress and post-term birth (≥42 weeks). We hypothesize that prolonging gestation past term may represent an adaptive strategy to a suboptimal environment. Methodology. We examined the relationship between exposure to the September 2001 terrorist attacks and odds of post-term birth in California. We calculated the expected odds of post-term birth among conception cohorts of singleton gestations in California between October 1996 and November 2005. We used time series analysis to test for higher than expected odds of post-term birth among the 10 cohorts exposed to the attacks of September 2001 (those conceived from December 2000 to September 2001). Results. The observed odds of post-term delivery among gestations at 33-36 weeks in September 2001 were higher than statistically expected for all race/ethnic and sex groups. Conclusions and implications. Our finding that odds of post-term birth were higher than expected among pregnancies exposed to the September 2001 terrorist attacks in late gestation provides initial support for the hypothesis that exposure to a psychosocial stress during pregnancy may result in prolonged gestation. © The Author(s) 2015. Published by Oxford University Press on behalf of the Foundation for Evolution, Medicine, and Public Health.
    01/2015; 2015(1). DOI:10.1093/emph/eov001