Sociodemographic, health behavioral, and clinical risk factors for anotia/microtia in a population-based case-control study

Objective: Anotia and microtia are congenital malformations of the external ear with few known risk factors. We conducted a comprehensive assessment of a wide range of potential risk factors using data from the National Birth Defects Prevention Study (NBDPS), a population-based case-control study of non-chromosomal structural birth defects in the United States. Methods: Mothers of 699 infants with anotia or microtia (cases) and 11,797 non-malformed infants (controls) delivered between 1997 and 2011 were interviewed to obtain information about sociodemographic, health behavioral, and clinical characteristics. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were estimated with logistic regression. Results: Infants with anotia/microtia were more likely to be male (aOR, 1.29; 95% CI, 1.10–1.50) and from a multifetal pregnancy (aOR, 1.68; 95% CI, 1.16–2.42). Cases were also more likely to have parents of Hispanic ethnicity (maternal aOR, 3.19; 95% CI, 2.61–3.91; paternal aOR, 2.11; 95% CI, 1.54–2.88), and parents born outside the United States (maternal aOR, 1.29; 95% CI, 1.06–1.57; paternal aOR, 1.92; 95% CI, 1.53–2.41). Maternal health conditions associated with increased odds of anotia/microtia included obesity (aOR, 1.31; 95% CI, 1.06–1.61) and pre-pregnancy diabetes (type I aOR, 9.89; 95% CI, 5.46–17.92; type II aOR, 4.70; 95% CI, 2.56–8.63). Reduced odds were observed for black mothers (aOR, 0.57; 95% CI, 0.38–0.85) and mothers reporting daily intake of folic acid-containing supplements (aOR, 0.59; 95% CI, 0.46–0.76). Conclusion: We identified several risk factors for anotia/microtia, some which have been previously reported (e.g., diabetes) and others which we investigate for perhaps the first time (e.g., binge drinking) that warrant further investigation. Our findings point to some potentially modifiable risk factors and provide further leads toward understanding the etiology of anotia/microtia

Association between maternal periconceptional alcohol consumption and neural tube defects: Findings from the National Birth Defects Prevention Study, 1997–2011

Background: Neural tube defects (NTD)s are common birth defects with a multifactorial etiology. Findings from human studies examining environmental (non-inherited) exposures tend to be inconclusive. In particular, although animal studies of alcohol exposure and NTDs support its teratogenic potential, human studies are equivocal. Using data from the National Birth Defects Prevention Study (NBDPS), associations between maternal periconceptional (1 month before through 1 month after conception) alcohol consumption and NTDs in offspring were examined. Methods: NTD cases and unaffected live born singleton controls with expected dates of delivery from October 1997–December 2011 were enrolled in the NBDPS. Interview reports of alcohol consumption (quantity, frequency, variability, type) from 1,922 case and 11,251 control mothers were analyzed. Crude and adjusted odds ratios (aOR)s and 95% confidence intervals (CI)s for alcohol consumption and all NTDs combined and selected subtypes (spina bifida, anencephaly, encephalocele) were estimated using unconditional logistic regression analysis. Results: Among mothers in the NBDPS, 28% of NTD case and 35% of control mothers reported any periconceptional alcohol consumption. For each measure of alcohol consumption, inverse associations were observed for all NTDs combined (aORs = 0.6–1.0). Results for NTD subtypes tended to be similar, but CIs for spina bifida and encephalocele were more likely to include the null. Conclusions: These findings suggest a lack of positive associations between maternal periconceptional alcohol consumption and NTDs. Future studies should continue to evaluate the association between maternal alcohol consumption and NTDs in offspring accounting for methodological limitations such as potential misclassification from self-reported alcohol consumption

Survival of infants with spina bifida and the role of maternal prepregnancy body mass index

Objective: To investigate first-year survival of infants born with spina bifida, and examine the association of maternal prepregnancy body mass index (BMI) with infant mortality. Methods: This is a retrospective cohort study of 1,533 liveborn infants with nonsyndromic spina bifida with estimated dates of delivery from 1998 to 2011 whose mothers were eligible for the National Birth Defects Prevention Study (NBDPS). NBDPS data were linked to death records to conduct survival analyses. Kaplan–Meier survival functions estimated mortality risk over the first year of life. Cox proportional hazards models estimated hazard ratios (HRs) for maternal prepregnancy BMI categorized as underweight ('18.5), normal (18.5–24.9), overweight (25–29.9), and obese (≥30). Results: Infant mortality risk among infants with spina bifida was (4.4% [3.52, 5.60%]). Infants with multiple co-occurring defects, very preterm delivery, multiple gestation, high-level spina bifida lesions, or non-Hispanic Black mothers had an elevated risk of infant mortality. Maternal prepregnancy underweight and obesity were associated with higher infant mortality (15.7% [7.20, 32.30%] and 5.82% [3.60, 9.35%], respectively). Adjusted HR estimates showed underweight and obese mothers had greater hazard of infant mortality compared to normal weight mothers (HR: 4.5 [1.08, 16.72] and 2.6 [1.36, 8.02], respectively). Conclusion: The overall risk of infant mortality for infants born with spina bifida was lower than most previously reported estimates. Infants born with spina bifida to mothers who were underweight or obese prepregnancy were at higher risk of infant mortality. This study provides additional evidence of the importance of healthy maternal weight prior to pregnancy

Tuataras and salamanders show that walking and running mechanics are ancient features of tetrapod locomotion

The lumbering locomotor behaviours of tuataras and salamanders are the best examples of quadrupedal locomotion of early terrestrial vertebrates. We show they use the same walking (out-of-phase) and running (in-phase) patterns of external mechanical energy fluctuations of the centre-of-mass known in fast moving (cursorial) animals. Thus, walking and running centre-of-mass mechanics have been a feature of tetrapods since quadrupedal locomotion emerged over 400 million years ago. When walking, these sprawling animals save external mechanical energy with the same pendular effectiveness observed in cursorial animals. However, unlike cursorial animals (that change footfall patterns and mechanics with speed), tuataras and salamanders use only diagonal couplet gaits and indifferently change from walking to running mechanics with no significant change in total mechanical energy. Thus, the change from walking to running is not related to speed and the advantage of walking versus running is unclear. Furthermore, lumbering mechanics in primitive tetrapods is reflected in having total mechanical energy driven by potential energy (rather than kinetic energy as in cursorial animals) and relative centre-of-mass displacements an order of magnitude greater than cursorial animals. Thus, large vertical displacements associated with lumbering locomotion in primitive tetrapods may preclude their ability to increase speed