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Is maternal parity an independent risk factor for birth defects?
Journal article   Peer reviewed

Is maternal parity an independent risk factor for birth defects?

Hao T Duong, Adrienne T Hoyt, Suzan L Carmichael, Suzanne M Gilboa, Mark A Canfield, Amy Case, Melanie L McNeese, Dorothy Kim Waller and National Birth Defects Prevention Study
Birth defects research. A Clinical and molecular teratology, Vol.94(4), pp.230-236
04/2012
DOI: 10.1002/bdra.22889
PMCID: PMC4476024
PMID: 22371332

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Abstract

BACKGROUND Although associations between maternal parity and birth defects have been observed previously, few studies have focused on the possibility that parity is an independent risk factor for birth defects. We investigated the relation between levels of parity and a range of birth defects, adjusting each defect group for the same covariates. METHODS We included infants who had an estimated delivery date between 1997 and 2007 and participated in the National Birth Defects Prevention Study, a multisite case-control study. Cases included infants or fetuses belonging to 38 phenotypes of birth defects (n = 17,908), and controls included infants who were unaffected by a major birth defect (n = 7173). Odds ratios (ORs) were adjusted for 12 covariates using logistic regression. RESULTS Compared with primiparous mothers, nulliparous mothers were more likely to have infants with amniotic band sequence, hydrocephaly, esophageal atresia, hypospadias, limb reduction deficiencies, diaphragmatic hernia, omphalocele, gastroschisis, tetralogy of Fallot, and septal cardiac defects, with significant ORs (1.2 to 2.3). Compared with primiparous mothers, multiparous mothers had a significantly increased risk of omphalocele, with an OR of 1.5, but had significantly decreased risk of hypospadias and limb reduction deficiencies, with ORs of 0.77 and 0.77. CONCLUSIONS Nulliparity was associated with an increased risk of specific phenotypes of birth defects. Most of the phenotypes associated with nulliparity in this study were consistent with those identified by previous studies. Research into biologic or environmental factors that are associated with nulliparity may be helpful in explaining some or all of these associations.
congenital abnormalities congenital heart defects multiparity nulliparity parity

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