Dataset Information

The association of maternal age with birthweight and gestational age: a cross-cohort comparison.

ABSTRACT:

Background

We examined the associations of maternal age with low birthweight (LBW) and preterm birth in four cohorts from a middle- and a high-income country, where the patterning of maternal age by socio-economic position (SEP) is likely to differ.

Methods

Population-based birth cohort studies were carried out in the city of Pelotas, Brazil in 1982, 1993, and 2004, and in Avon, UK in 1991 [Avon Longitudinal Study of Parents and Children (ALSPAC)]. Adjustment for multiple indicators of SEP were applied.

Results

Low SEP was associated with younger age at childbearing in all cohorts, but the magnitudes of these associations were stronger in ALSPAC. Inverse associations of SEP with LBW and preterm birth were observed in all cohorts. U-shaped associations were observed between maternal age and odds of LBW in all cohorts. After adjustment for SEP, increased odds of LBW for young mothers (<20 years) attenuated to the null but remained or increased for older mothers (? 35 years). Very young (<16 years) maternal age was also associated with both outcomes even after full SEP adjustment. SEP adjusted odds ratio of having a LBW infant in women <16 years and ? 35 years, compared with 25-29 years, were 1.48 [95% confidence interval (CI) 1.00, 2.20] and 1.66 [95% CI 1.36, 2.02], respectively. The corresponding results for preterm birth were 1.80 [95% CI 1.23, 2.64)] and 1.38 [95% CI 1.15, 1.67], respectively.

Conclusion

Confounding by SEP explains much of the excess risk of LBW and preterm among babies born to teenage mothers as a whole, but not for mothers aged <16 or ? 35 years. Given that the proportion of women becoming pregnant at <16 years is smaller than for those ? 35 years, the population burden is greater for older age.

SUBMITTER: Restrepo-Mendez MC

PROVIDER: S-EPMC4296235 | biostudies-literature | 2015 Jan

REPOSITORIES: biostudies-literature

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Publications

The association of maternal age with birthweight and gestational age: a cross-cohort comparison.

Restrepo-Méndez María Clara MC Lawlor Debbie A DA Horta Bernardo L BL Matijasevich Alicia A Santos Iná S IS Menezes Ana M B AM Barros Fernando C FC Victora Cesar G CG

Paediatric and perinatal epidemiology 20141118 1

<h4>Background</h4>We examined the associations of maternal age with low birthweight (LBW) and preterm birth in four cohorts from a middle- and a high-income country, where the patterning of maternal age by socio-economic position (SEP) is likely to differ.<h4>Methods</h4>Population-based birth cohort studies were carried out in the city of Pelotas, Brazil in 1982, 1993, and 2004, and in Avon, UK in 1991 [Avon Longitudinal Study of Parents and Children (ALSPAC)]. Adjustment for multiple indicato ...[more]

PMID: 25405673

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Project description:BackgroundPrevious studies observed associations between prenatal exposure to fine particulate matter (≤ 2.5 μm; PM2.5) and small-for-gestational-age (SGA) birth and lower birthweight percentile for gestational age. Few, if any, studies examine prenatal air pollution exposure and these pregnancy outcomes in neonates born to the same women. Here, we assess whether prenatal exposure to ambient fine particulate matter (PM2.5) is associated with small-for-gestational-age (SGA) birth or birthweight percentile for gestational age in a longitudinal setting.MethodsDetailed birth record data were used to identify women who had singleton live births at least twice in North Carolina during 2002-2006 (n = 53,414 women, n = 109,929 births). Prenatal PM2.5 exposures were calculated using daily concentration estimates obtained from the US EPA Fused Air Quality Surface using Downscaling data archive. Associations between PM2.5 exposure and birthweight percentile and odds of SGA birth were calculated using linear and generalized mixed models, comparing successive pregnancies to the same woman. Odds ratios and associations were also estimated in models that did not account for siblings born to the same mother.ResultsAmong NHW women, pregnancy-long PM2.5 exposure was associated with SGA (OR: 1.11 [1.06, 1.18]) and lower birthweight percentile (- 0.46 [- 0.74, - 0.17]). Trimester-specific PM2.5 was also associated with SGA and lower birthweight percentile. Among NHB women, statistically significant within-woman associations between PM2.5, SGA, and birthweight percentile were not observed. However, in models that did not account for births to the same mother, statistically significant associations were observed between some PM2.5 exposure windows and higher odds of SGA and lower birthweight percentile among NHB women.ConclusionsFindings suggest that a woman is at greater risk of delivering an SGA or low birthweight percentile neonate when she has been exposed to higher PM2.5 levels. The within-woman comparison implemented here better controls for factors that may differ between women and potentially confound the relationship between PM2.5 exposure and pregnancy outcomes. This adds to the evidence that PM2.5 exposure may be causally related to SGA and birthweight percentile, even at concentrations close to or below National Ambient Air Quality Standards.

Project description:This study aims to evaluate the association of maternal DNA methylation (DNAm) during pregnancy and offspring birthweight. One hundred twenty-two newborn-mother dyads from the Isle of Wight (IOW) cohort were studied to identify differentially methylated cytosine-phosphate-guanine sites (CpGs) in maternal blood associated with offspring birthweight. Peripheral blood samples were drawn from mothers at 22-38 weeks of pregnancy for epigenome-wide DNAm assessment using the Illumina Infinium HumanMethylation450K array. Candidate CpGs were identified using a course of 100 repetitions of a training and testing process with robust regressions. CpGs were considered informative if they showed statistical significance in at least 80% of training and testing samples. Linear mixed models adjusting for covariates were applied to further assess the selected CpGs. The Swedish Born Into Life cohort was used to replicate our findings (n = 33). Eight candidate CpGs corresponding to the genes LMF1, KIF9, KLHL18, DAB1, VAX2, CD207, SCT, SCYL2, DEPDC4, NECAP1, and SFRS3 in mothers were identified as statistically significantly associated with their children's birthweight in the IOW cohort and confirmed by linear mixed models after adjusting for covariates. Of these, in the replication cohort, three CpGs (cg01816814, cg23153661, and cg17722033 with p values = 0.06, 0.175, and 0.166, respectively) associated with four genes (LMF1, VAX2, CD207, and NECAP1) were marginally significant. Biological pathway analyses of three of the genes revealed cellular processes such as endocytosis (possibly sustaining an adequate maternal-fetal interface) and metabolic processes such as regulation of lipoprotein lipase activity (involved in providing substrates for the developing fetus). Our results contribute to an epigenetic understanding of maternal involvement in offspring birthweight. Measuring DNAm levels of maternal CpGs may in the future serve as a diagnostic tool recognizing mothers at risk for pregnancies ending with altered birthweights.

Dataset Information

The association of maternal age with birthweight and gestational age: a cross-cohort comparison.

Background

Methods

Results

Conclusion

Publications

The association of maternal age with birthweight and gestational age: a cross-cohort comparison.

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