Abstract
Preterm delivery (PTD; ≤37 weeks gestation) in the United States is a challenging condition associated with potential long-term adverse developmental and adverse health effects for the infant. PTD is an enigma for which randomized trials of antibiotics and other interventions have revealed null results for decades. Given the condition with its persistent ∼10% rate defies effective multiple interventions.
In this issue of the Journal of Women's Health, Kerver et al. 1 reveal that women with total serum carotenoids in the upper quartile (Q4) had significantly lower odds ratios of medically indicated PTD compared with women in the lower quartiles (Q1–Q3) after adjustment for maternal and other characteristics (adjusted odds ratio = 0.4; 95% confidence interval: 0.20–0.90). The results are based on a prospective observational cohort study entitled the Pregnancy Outcomes and Community Health (POUCH) study with blood biomarkers collected in the nonfasting state during the second trimester of pregnancy. Of import, the results focus on a potentially targetable intervenable subgroup of women with hypertensive pregnancy and other comorbidity indicating the need for medically induced delivery. Health care providers, therefore, have diagnosed these conditions, can identify these women, and there may be time before delivery to provide dietary or other interventions. The authors are careful, however, to present limitations and do not take leaps in thought by overinterpreting the results. They recognize that high concentrations of total carotenoids may be a marker for a healthy lifestyle, higher socioeconomic status, or/and healthy diet. What we need is to consider what's next?
Total carotenoids are found in abundance in many fruit and vegetables, with tomato and tomato products rich in lycopene, dark green vegetables rich in lutein, and along with orange and yellow vegetables rich in beta carotene, whereas corn is rich in zeaxanthin and oranges have high concentrations of beta-cryptoxanthin. Given the array of carotenoid-rich fruit and vegetables, it is important to note the same fruit and vegetables have other antioxidants such as vitamin C. This article focuses on total carotenoids in blood not vitamin C status. The study did not collect dietary data to determine the food contributors to serum carotenoid concentrations nor to compute a diet-biochemical correlation indicative that the serum concentrations are dietary biomarkers of food—fruit and/or vegetables—or individual carotenoids. The large majority of carotenoids are carried by the low-density lipoprotein, whereas lutein and zeaxanthin are carried on both the high and low lipoproteins. Essential functions of lipoproteins include, for example, protein carriers of lipophilic micronutrients that have antioxidant capacity to reduce oxidative stress and hormone metabolism. Which function(s) of the carotenoids and lipoproteins plays a role in reduction of PTD is unclear. Further research is to clarify function and role of both the carotenoids and lipoproteins in pregnancy with PTD as well as compute diet-biochemical associations that shed light on food contributors to target dietary interventions. With one prior Canadian study revealing similar results, 2 additional observational cohort studies are important next steps for reproducibility.
Prenatal vitamin mineral supplements do not typically include carotenoids, but have high amounts of vitamin A, which can be formed by conversion of the provitamin A carotenoids of lycopene, beta-, and alpha-carotene to retinol and its metabolites. It is not the intent to recommend adding carotenoids as magic bullets to prenatal supplements after the disastrous effects from randomized trials of beta-carotene in smokers that increased, not decreased, risk of lung cancer. 3,4 It is the intent to shed a glimmer of hope that a focus on a healthy lifestyle before and during pregnancy may improve the health status of the triad of the mother, placenta, and fetus at risk for PTD with potential preventative effects across the life course.