The association between parity and birthweight in a longitudinal consecutive pregnancy cohort.
Paediatr Perinat Epidemiol
; 28(2): 106-15, 2014 Mar.
Article
en En
| MEDLINE
| ID: mdl-24320682
ABSTRACT
BACKGROUND:
Nulliparity is associated with lower birthweight, but few studies have examined how within-mother changes in risk factors impact this association.METHODS:
We used longitudinal electronic medical record data from a hospital-based cohort of consecutive singleton live births from 2002-2010 in Utah. To reduce bias from unobserved pregnancies, primary analyses were limited to 9484 women who entered nulliparous from 2002-2004, with 23,380 pregnancies up to parity 3. Unrestricted secondary analyses used 101,225 pregnancies from 45,212 women with pregnancies up to parity 7. We calculated gestational age and sex-specific birthweight z-scores with nulliparas as the reference. Using linear mixed models, we estimated birthweight z-score by parity adjusting for pregnancy-specific sociodemographics, smoking, alcohol, prepregnancy body mass index, gestational weight gain, and medical conditions.RESULTS:
Compared with nulliparas', infants of primiparas were larger by 0.20 unadjusted z-score units [95% confidence interval (CI) 0.18, 0.22]; the adjusted increase was similar at 0.18 z-score units [95% CI 0.15, 0.20]. Birthweight continued to increase up to parity 3, but with a smaller difference (parity 3 vs. 0 ß = 0.27 [95% CI 0.20, 0.34]). In the unrestricted secondary sample, there was significant departure in linearity from parity 1 to 7 (P < 0.001); birthweight increased only up to parity 4 (parity 4 vs. 0 ß = 0.34 [95% CI 0.31, 0.37]).CONCLUSIONS:
The association between parity and birthweight was non-linear with the greatest increase observed between first- and second-born infants of the same mother. Adjustment for changes in weight or chronic diseases did not change the relationship between parity and birthweight.Palabras clave
Texto completo:
1
Banco de datos:
MEDLINE
Asunto principal:
Paridad
/
Peso al Nacer
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Aumento de Peso
Tipo de estudio:
Etiology_studies
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Observational_studies
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Prognostic_studies
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Risk_factors_studies
Límite:
Adolescent
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Adult
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Female
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Humans
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Male
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Pregnancy
Idioma:
En
Revista:
Paediatr Perinat Epidemiol
Asunto de la revista:
EPIDEMIOLOGIA
/
PEDIATRIA
/
PERINATOLOGIA
Año:
2014
Tipo del documento:
Article
País de afiliación:
Moldova