New research published in the British Medical Journal suggests that vitamin D during pregnancy may not play much of a role in cardiovascular disease in offspring.
There is increasing evidence that vitamin D during pregnancy is important for proper fetal development and growth. Low vitamin D status during pregnancy has been associated with an increased risk of a variety of conditions in offspring later in life. For example, some research shows infants and children have an increased risk of developing type 1 diabetes, wheezing and low bone mineral density if their mother was deficient in vitamin D during pregnancy.
To date, there isn’t much research examining the effect of vitamin D status during pregnancy and risk of cardiovascular disease in offspring. Since low vitamin D levels might be related to increased risk of insulin resistance in offspring, theoretically, there might be a link between cardiovascular disease in offspring and vitamin D deficiency during pregnancy.
Researchers decided to find out.
They took a look at the ALSPAC cohort, a cohort that consisted of over 14,000 pregnant women. Researchers collected blood samples, other markers and surveys from these women in the years of 1991 and 1992. One of the many things they measured included vitamin D levels.
The researchers then followed the offspring of these mothers for many years, including follow-up times of 9.9 and 15.4 years after birth. In these follow-up periods, researchers also collected blood samples and took other measurements of the children. In relevance to the current study, research took a look at cardiovascular risk factors, including blood pressure, lipids, apolopoproteins, fasting glucose and insulin, C-reactive protein (CRP), and interleukin 6 (IL6).
Of the 14,000 original pregnant mothers enrolled in the study, the researchers were able to collect enough data on 4,109 mother-offspring pairs.
When the researchers looked at the data, and matched vitamin D levels during pregnancy and cardiovascular risk factor markers of children, here is what they found:
- At 9.9 years, HDL cholesterol and Apo-A1 of children increased as vitamin D levels increased in pregnant mothers (from under 10 ng/ml to over 30 ng/ml).
- At 9.9 years, diastolic blood pressure, LDL cholesterol and Apo-B of children decreased as vitamin D levels increased in pregnant mothers (from under 10 ng/ml to over 30 ng/ml). Statistical significance was somewhat weak, and clinical significance was not major.
- The researchers observed similar trends at 15.4 years for LDL, HDL and CRP.
- However, when researchers adjusted their data for a variety of variables, associations became weaker or nonexistent.
- When the researchers tried looking at data based on vitamin D status of first, second or third trimesters, there were no particular associations or trends.
The researchers concluded,
“Although our results suggest the possibility of associations of higher 25(OH)D with healthier concentrations of CRP (and also Apo-B), further prospective studies are required to confirm the findings and experimental studies are required to increase our understandings of potential mechanisms.”
The thing to understand here is that researchers are working hard to answer the following questions in vitamin D:
- What conditions and diseases does vitamin D play a role in?
- Of the conditions and diseases vitamin D plays a role in, at what time in life is vitamin D most important for the prevention of that condition or disease?
In the case here, it could be that vitamin D status during pregnancy doesn’t much influence offspring’s cardiovascular health. More research is required, however. Researchers do think vitamin D plays a role in cardiovascular diseases; to what extent they’re still trying to discover. This research, taken with other research, suggests that vitamin D during childhood and adulthood is important for cardiovascular health, while during pregnancy, maybe not as much.
Williams DM et al. Associations of maternal 25-hydroxyvitamin D in pregnancy with offspring cardiovascular risk factors in childhood and adolescence: findings from the Avon Longitudinal Study of Parents and Children. British Medical Journal, 2013.