Some babies seem to have a genetic predisposition to a higher risk of being born too soon, according to researchers in a study to be presented on Feb. 5 in an oral concurrent session at 8 a.m. PST, at the Society for Maternal-Fetal Medicine's annual meeting in San Diego. The study titled Neonatal, not Maternal, Copy Number Variants are Associated with Spontaneous Preterm Birth found that variants in the fetus's DNA - not the mother's - may be what triggers some early births.
Joseph R. Biggio, MD, of the University of Alabama, and his colleagues from the Eunice Kennedy Shriver Genomics and Proteomics Network for Preterm Birth Research analyzed the number of copies of certain genes in the blood or saliva from hundreds of babies and their mothers. While there was no link between the number of copies of the mother's genes and the chances of a preterm baby, there was a two- to eleven-fold increase in preterm births before 34 weeks of pregnancy when any of four genes were duplicated or seven genes were deleted in the babies born preterm, when compared to babies born full-term.
"These findings may help explain what triggers early labor in some women even when they've done everything right during pregnancy and there's no obvious cause for an early birth," explained March of Dimes Chief Medical Officer Edward R. B. McCabe, MD, MPH. "The hope is that this finding may one day lead to a screening test to help identify which babies are at a higher risk of an early birth."
The preterm birth rate in the United States dropped more than 10 percent between 2013 and 2006, with most of the improvement focused in late preterm births (those between 34 and 37 weeks of pregnancy). Today's research findings focused on early preterm births, births before 34 weeks of pregnancy, in which there has been little improvement in recent years.
More than 450,000 babies are born too soon each year in the U.S. Preterm birth (birth before 37 weeks of pregnancy) is the leading cause of newborn death, and babies who survive an early birth often face an increased risk of a lifetime of health challenges, such as breathing problems, cerebral palsy, intellectual disabilities and others. Even babies born just a few weeks early have higher rates of hospitalization and illness than full-term infants. It is a serious health problem that costs the United States more than $26 billion annually.
Dr. Biggio's research is being honored by the March of Dimes at the annual Society for Maternal Fetal Medicine. Dr. McCabe presented Dr. Biggio with the March of Dimes award for Best Abstract in Prematurity at the SMFM's Annual Meeting. 2015 marks the 12th year the March of Dimes award has been presented.
While the differences in the number of copies of the genes may not be causing a preterm birth, they may put a baby at a higher risk of infection or reacting to other harmful environmental factors that may trigger early labor and delivery, explained Dr. Biggio.
It may also help explain why treatment with progesterone, a naturally-occurring hormone in pregnancy shown to prevent some preterm births, work for only about one-third of women.
"We always thought we were treating the mother with progesterone, but perhaps we were actually treating the baby," Dr. Biggio said. Dr. Biggio's research was funded by the Eunice Kennedy Shriver National Institute of Child health and Human Development.
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The Society for Maternal-Fetal Medicine (est. 1977) is the premiere membership organization for obstetricians/gynecologists who have additional formal education and training in maternal-fetal medicine. The society is devoted to reducing high-risk pregnancy complications by sharing expertise through continuing education to its 2,000 members on the latest pregnancy assessment and treatment methods. It also serves as an advocate for improving public policy, and expanding research funding and opportunities for maternal-fetal medicine. The group hosts an annual meeting in which groundbreaking new ideas and research in the area of maternal-fetal medicine are shared and discussed. Visit http://www.smfm.org.
The March of Dimes is the leading nonprofit organization for pregnancy and baby health. For more than 75 years, moms and babies have benefited from March of Dimes research, education, vaccines, and breakthroughs. Find out how you can help prevent premature birth and birth defects by joining March for Babies at marchforbabies.org. For the latest resources and information, visit marchofdimes.org or nacersano.org. Find us on Facebook and Twitter.
Abstract 9: Neonatal, not Maternal, Copy Number Variants are Associated with Spontaneous Preterm Birth
Authors: Joseph R. Biggio1, Feifei Xiao1, Don Baldwin1, Radek Bukowski1, Samuel
Parry1, M. S. Esplin1, William W. Andrews1, George Saade1, Michael Varner1, Yoel Sadovsky1, Uma Reddy1, JohnIlekis1, Heping Zhang1
1. for the Eunice Kennedy Shriver NICHD Genomics and Proteomics Network for Preterm Birth Research, Bethesda,MD, United States.
Objective: Copy number variants (CNVs) contribute to human genetic diversity and are associated with complex disorders. Given the complex nature of spontaneous preterm birth (SPTB), we sought to examine the association between maternal or neonatal CNVs and SPTB at <34 wks.
Study Design: Case-control study of singleton SPTB <34 wks compared to spontaneous labor at 39-40 wks. Maternal and neonatal DNA obtained from either blood or saliva was analyzed on Affymetrix Human SNP Array 6.0. CNVs were identified using PennCNV software; those containing > 5 consecutive SNPs and >10kb were retained. Results were filtered based on genotyping quality controls. CNVs with copy number >2 were defined as duplications and <2 as deletions. CNV distribution, type, and size were compared in a global burden analysis. Gene- and region-based CNV association strategies were utilized in logistic regression models as well as in PLINK software. Bonferroni correction adjusted for multiple comparisons.
Results: 901 maternal cases and 900 controls were analyzed. Mean CNV size and numbers were similar, but the proportion of CNV that were deletions was higher in cases (63.4 vs 62.2%, p=0.04). Neither gene- nor region-based association studies correlated with SPTB. 787 neonatal cases and 785 controls were analyzed. CNV size and number did not differ, but the proportion of CNV that were deletions was higher in cases (73.7 vs 71.3%, p=1.6x10-11). SPTB associated deletions and duplications were noted across the genome including chromosomes 2, 4, 5, 6, 8, 10, 13, and 21.(Table) In gene-based analysis, a duplication of 3 consecutive genes on 11q11-12 (OR4P4, OR4C6 and OR4S2) and one on 11p15 involving RASSF7 were associated with SPTB. In gene region-based PLINK analysis, deletions involving 7 genes and duplications involving 3 were significantly associated with SPTB. Conclusion: Neonatal, but not maternal, CNVs are associated with early SPTB. The effects of the involved genes require further investigation and these CNVs should be examined in additional cohorts.
Neonatal CNVs and SPTB--Logistic regression and PLINK analysis