Better maternal diet in the year prior to conception was associated with lower risk of serious congenital heart defects, according to the results of a large retrospective case-control analysis using data from the National Birth Defects Prevention Study.
In adjusted analyses, Lorenzo D. Botto, MD, of the University of Utah in Salt Lake City, and colleagues found a reduced risk of all conotruncal defects (aOR 0.76, 95% CI 0.64 to 0.91), as well as a 37% reduced risk in tetralogy of Fallot (aOR 0.63, CI 0.49 to 0.80) associated with the highest quartile of Diet Quality Index for pregnancy (DQI-P).
The authors also observed diet quality was associated with a slightly lower risk of overall septal defects (aOR 0.86, 95% CI 0.75 to 1.00), including atrial septal defects (aOR 0.77, 95% CI 0.63 to 0.94). They published their results in Archives of Disease in Childhood: Fetal and Neonatal Edition.
John P. Breinholt, MD, division director of pediatric cardiology at The University of Texas Health Science Center at Houston/Children’s Memorial Hermann Hospital, said that population studies are always difficult as they require sifting through a lot of factors that can influence the outcome, the authors were meticulous in their process in demonstrating that there appears to be a nutritional component to the development of congenital heart disease. Breinholt was not involved with the study.
“This emphasizes more than ever the need to educate women to prepare themselves nutritionally for childbirth (in addition to during pregnancy), as well as further identify the dietary factors that can prevent these significant birth defects,” he told MedPage Today via e-mail.
Researchers adjusted for maternal energy intake, race/ethnicity, folic acid supplement use, smoking, maternal education, maternal BMI, and study center.
Botto told MedPage Today that birth defects are a significant clinical and public health issue, with one in four infant deaths from birth defects caused by a heart anomaly, but that little is known about how to prevent them. He added that the National Birth Defects Prevention Study had looked at diet as a factor for structural malformations, such as spina bifida and cleft lip and palate. So, his team wanted to test the hypothesis that diet would also help with congenital heart anomalies.
“There’s been a very reasonable focus on prenatal care, but to maximize primary prevention for heart defects and other structural malformations, we’ve got to go even a step further and really focus on preconception care,” Botto said.
When examining the diet questionnaire results by decile, researchers observed similar patterns, including an overall reduced risk of conotruncal defects (10th decile versus 1st decile, aOR 0.66, 95% CI 0.50 to 0.87). The strongest associations with diet quality and specific conotruncal and septal heart defects were observed for:
- Tetralogy of Fallot: aOR 0.55 , CI 0.38 to 0.79
- dTGA: aOR 0.58, CI 0.36 to 0.93
- ASD secundum: aOR 0.59, CI 0.43 to 0.81
Researchers used two dietary indices, the DQI-P, as well as the Mediterranean Diet Score, and found significant risk reduction for these congenital heart defects only with the DQI-P (a shortened 58-item version of the diet questionnaire from the Nurse’s Health Study).
The study examined data from mothers of babies with major non-syndromic congenital heart defects (n=9,885) and mothers with unaffected babies as matched controls (n=9,468) with estimated dates of delivery from 1997 to 2009. Participants were excluded if mothers reported pregestational diabetes, had an average daily intake of <500 or >5,000 kcal or had missing data on two or more food items. Of the control sample, 18% smoked in early pregnancy, 38% were overweight or obese, and 76% reported using folic acid supplements during the periconceptional period.
Limitations to the study include the inability to validate reported dietary intakes (as they were self-reported), as well as potential residual confounding, selection, and recall bias.
Botto also noted that the study was observational, but that it took a more holistic approach to dietary pattern than previous studies, and hoped that an independent study might replicate its results. He added that it might be worth examining if any specific components of the diet had a protective effect.
Breinholt agreed with the need for additional research, concluding “more study is definitely warranted in this area, but this is an important first step that establishes a key target.”